@article {1660,
	title = {Ambient Ammonia Electrosynthesis from Nitrogen and Water by Incorporating Palladium in Bimetallic Gold{\textendash}Silver Nanocages},
	journal = {Journal of The Electrochemical Society},
	year = {2020},
	author = {Nazemi, M. and Soule, L. and Liu, M. and El-Sayed, M. A.}
}
@article {1661,
	title = {Electrosynthesis of Ammonia Using Porous Bimetallic Pd{\textendash}Ag Nanocatalysts in Liquid- and Gas-Phase Systems},
	journal = {ACS Catalysis},
	year = {2020},
	chapter = {10197},
	keywords = {display},
	author = {Nazemi, M. and Ou, P. and Alabbady, A. and Soule, L. and Liu, A. and Song, J. and Sulchek, T.A. and Liu, M. and El-Sayed, M. A.}
}
@article {1653,
	title = {Gold nanomaterials as key suppliers in biological and chemical sensing, catalysis, and medicine},
	journal = {Biochimica et Biophysica Acta (BBA)-General Subjects},
	year = {2020},
	author = {Falahati, M. and Attar, F. and Sharifi, M. and Saboury, A.A. and Salihi, A. and Aziz, F.M. and Kostova, I. and Burda, C. and Priecel, P. and Lopez-Sanchez, J.A. and Laurent, S. and Hooshmand, N. and El-Sayed, M.A.}
}
@article {1658,
	title = {Observation of Photoinduced Proton Transfer between the Titania Surface and Dye Molecule},
	journal = {The Journal of Physical Chemistry C},
	year = {2020},
	author = {Nishikiori, H. and Kondo, H. and Kageshima, Y. and Hooshmand, N. and Panikkanvalappil, S. R. and Valverde-Ch{\'a}vez, D.A. and Silva, C. and El-Sayed, M.A. and Teshima,K.}
}
@article {1659,
	title = {Plasmonic and chiroplasmonic nanobiosensors based on gold nanoparticles},
	journal = {Talanta},
	year = {2020},
	author = {Sharifi, M. and Hosseinali, S.H. and Alizadeh, R.H. and Hasan, A. and Attar, F. and Salihi, A. and Shekha, M.S. and Amen, K.M. and Aziz, F.M. and Saboury, A.A. and Akhtari, K. and Taghizadeh, A. and Hooshmand, N. and El-Sayed, M. A. and Falahati, M.}
}
@article {1652,
	title = {Enhancing Plasmonic{\textendash}Photonic Hybrid Cavity Modes by Coupling of Individual Plasmonic Nanoparticles},
	journal = {The Journal of Physical Chemistry C},
	year = {2019},
	author = {Zhang, S. and Panikkanvalappil, S.R. and Kang, S. and Smith, M.J. and Yu, S. and El-Sayed, M. and Tsukruk, V.V.}
}
@article {1650,
	title = {Gold Nanorod-Assisted Photothermal Therapy Decreases Bleeding during Breast Cancer Surgery in Dogs and Cats},
	journal = {Cancers},
	year = {2019},
	author = {Ali, M.R. and Farghali, H.A. and Wu, Y. and El-Sayed, I. and Osman, A.H. and Selim, S.A. and El-Sayed, M.A.}
}
@article {1651,
	title = {Plasmonic gold nanoparticles: Optical manipulation, imaging, drug delivery and therapy},
	journal = {Journal of Controlled Release},
	year = {2019},
	author = {Sharifi, M. and Attar, F. and Saboury, A.A. and Akhtari, K. and Hooshmand, N. and Hasan, A. and El-Sayed, M.A. and Falahati, M.}
}
@article {1592,
	title = { Photoexcited Surface Frustrated Lewis Pairs for Heterogeneous Photocatalytic Co2 Reduction},
	journal = { Am. Chem. Soc. },
	year = {2016},
	author = {Ghuman, K. K. and Hoch, L. B. and Szymanski, P. and Loh, J. Y. and Kherani, N. P. and El-Sayed, M. A. and Ozin, G. A. and Singh, C. V.}
}
@article {1620,
	title = {Virtual Issue in Memory of Ahmed Zewail},
	journal = {Journal of Physical Chemistry B},
	year = {2016},
	author = {El-Sayed, Mostafa A. and Schatz, GC}
}
@article {1573,
	title = {Electronic and Vibrational Dynamics of Hollow Au Nanocages Embedded in Cu2O Shells},
	journal = {Photochemistry and Photobiology},
	volume = {91},
	year = {2015},
	pages = {599{\textendash}606},
	issn = {1751-1097},
	doi = {10.1111/php.12432},
	url = {http://dx.doi.org/10.1111/php.12432},
	author = {Szymanski, Paul and Mahmoud, Mahmoud A. and O{\textquoteright}Neil, Daniel and Garlyyev, Batyr and El-Sayed, Mostafa A.}
}
@article {1575,
	title = {Light-responsive plasmonic arrays consisting of silver nanocubes and a photoisomerizable matrix.},
	journal = {ACS Appl Mater Interfaces},
	volume = {7},
	year = {2015},
	month = {2015 Mar 4},
	pages = {4902-12},
	abstract = {We report on the synthesis of novel branched organic-inorganic azo-polyhedral oligomeric silsesquioxane (POSS) conjugates (Azo-POSS) and their use as a stable active medium to induce reversible plasmonic modulations of embedded metal nanostructures. A dense monolayer of silver nanocubes was deposited on a quartz substrate using the Langmuir-Blodgett technique and subsequently coated with an ultrathin Azo-POSS layer. The reversible light-induced photoisomerization between the trans and cis states of the azobenzene-terminated branched POSS material results in significant changes in the refractive index (up to 0.17) at a wavelength of 380 nm. We observed that the pronounced and reversible change in the surrounding refractive index results in a corresponding hypsochromic plasmonic shift of 6 nm in the plasmonic band of the embedded silver nanocubes. The reversible tuning of the plasmonic modes of noble-metal nanostructures using a variable-refractive-index medium opens up the possibility of fabricating photoactive, hybrid, ultrathin coatings with robust, real-time, photoinitiated responses for prospective applications in photoactive materials that can be reversibly tuned by light illumination.},
	issn = {1944-8252},
	doi = {10.1021/am508993z},
	author = {Ledin, Petr A and Russell, Michael and Geldmeier, Jeffrey A and Tkachenko, Ihor M and Mahmoud, Mahmoud A. and Shevchenko, Valery and El-Sayed, Mostafa A. and Tsukruk, Vladimir V.}
}
@article {1574,
	title = {Near-Infrared Asymmetrical Squaraine Sensitizers for Highly Efficient Dye Sensitized Solar Cells: The Effect of π-Bridges and Anchoring Groups on Solar Cell Performance},
	journal = {Chemistry of Materials},
	volume = {27},
	year = {2015},
	pages = {2480-2487},
	doi = {10.1021/cm5045946},
	url = {http://dx.doi.org/10.1021/cm5045946},
	author = {Fadi M. Jradi and Xiongwu Kang and O{\textquoteright}Neil, Daniel and Gabriel Pajares and Yulia A. Getmanenko and Szymanski, Paul and Timothy C. Parker and El-Sayed, Mostafa A. and Seth R. Marder}
}
@article {1371,
	title = {Energy-Transfer Efficiency in Eu-Doped ZnO Thin Films: The Effects of Oxidative Annealing on the Dynamics and the Intermediate Defect States},
	journal = {Acs Applied Materials \& Interfaces},
	volume = {6},
	number = {3},
	year = {2014},
	note = {Ahmed, Samah M. Szymanski, Paul El-Nadi, Lotfia M. El-Sayed, Mostafa A.},
	month = {Feb},
	pages = {1765-1772},
	isbn = {1944-8244},
	doi = {10.1021/am404662k},
	author = {Ahmed, S. M. and Szymanski, P. and El-Nadi, L. M. and El-Sayed, M. A.}
}
@article {1356,
	title = {Self-Assembled Nanostructured Photoanodes with Staggered Bandgap for Efficient Solar Energy Conversion},
	journal = {ACS nano},
	year = {2014},
	isbn = {1936-0851},
	author = {Nashed, Ramy and Szymanski, Paul and El-Sayed, Mostafa A. and Allam, Nageh K}
}
@article {1376,
	title = {Electron transfer process in fluorescein-dispersing titania gel films observed by time-resolved fluorescence spectroscopy},
	journal = {The Journal of Physical Chemistry C},
	volume = {117},
	number = {20},
	year = {2013},
	pages = {10308-10314},
	isbn = {1932-7447},
	author = {Setiawan, Rudi Agus and Nishikiori, Hiromasa and Uesugi, Yohei and Miyashita, Kyohei and El-Sayed, Mostafa A. and Fujii, Tsuneo}
}
@article {1392,
	title = {Inducing Cancer Cell Death by Targeting Its Nucleus: Solid Gold Nanospheres versus Hollow Gold Nanocages},
	journal = {Bioconjugate Chemistry},
	volume = {24},
	number = {6},
	year = {2013},
	note = {Mackey, Megan A. Saira, Farhat Mahmoud, Mahmoud A. El-Sayed, Mostafa A.},
	month = {Jun},
	pages = {897-906},
	isbn = {1043-1802},
	doi = {10.1021/bc300592d},
	author = {Mackey, M. A. and Saira, F. and Mahmoud, M A and El-Sayed, M. A.}
}
@article {1374,
	title = {The Last Step in Converting the Surface Plasmonic Energy into Heat by Nanocages and Nanocubes on Substrates},
	journal = {Small},
	volume = {9},
	number = {23},
	year = {2013},
	note = {Szymanski, Paul Mahmoud, Mahmoud A. El-Sayed, Mostafa A.},
	month = {Dec},
	pages = {3934-3938},
	isbn = {1613-6810},
	doi = {10.1002/smll.201300233},
	author = {Szymanski, P. and Mahmoud, M A and El-Sayed, M. A.}
}
@article {1375,
	title = {Thermal/Electrochemical Growth and Characterization of One-Dimensional ZnO/TiO2 Hybrid Nanoelectrodes for Solar Fuel Production},
	journal = {Journal of Physical Chemistry C},
	volume = {117},
	number = {36},
	year = {2013},
	note = {Shaheen, Basamat S. Salem, Hanadi G. El-Sayed, Mostafa A. Allam, Nageh K.},
	month = {Sep},
	pages = {18502-18509},
	isbn = {1932-7447},
	doi = {10.1021/jp405515v},
	author = {Shaheen, B. S. and Salem, H. G. and El-Sayed, M. A. and Allam, N. K.}
}
@article {1398,
	title = {Tissue Distribution and Efficacy of Gold Nanorods Coupled with Laser Induced Photoplasmonic Therapy in Ehrlich Carcinoma Solid Tumor Model},
	journal = {Plos One},
	volume = {8},
	number = {10},
	year = {2013},
	note = {El-Sayed, Mostafa A. Shabaka, Ali A. El-Shabrawy, Osama A. Yassin, Nemat A. Mahmoud, Sawsan S. El-Shenawy, Siham M. Al-Ashqar, Emad Eisa, Wael H. Farag, Niveen M. El-Shaer, Marwa A. Salah, Nabila Al-Abd, Ahmed M.},
	month = {Oct},
	abstract = {Gold nanorods (GNR) within tumor microregions are characterized by their ability to absorb near IR light and emit heat in what is called photoplasmonic effect. Yet, the efficacy of nanoparticles is limited due to intratumoral tissue distribution reasons. In addition, distribution of GNRs to normal tissue might result in non specific toxicity. In the current study, we are assessing the intratumoral and tissue distribution of PEGylated GNRs on the top of its antitumor characteristics when given intravenously or intratumoral to solid tumor bearing mice and coupled with laser photoplasmonic sessions. PEGylated GNRs with a longitudinal size of less than 100 nm were prepared with aspect ratio of 4.6 showing strong surface plasmon absorption at wavelength 800 nm. Pharmacokinetics of GNR after single I.V. administration (0.1 mg/kg) showed very short systemic circulating time (less than 3 h). On the other hand, tissue distribution of I.V. GNR (0.1 mg/kg) to normal animals showed preferential deposition in spleen tissue. Repeated administration of I.V. GNR resulted in preferential accumulation in both liver and spleen tissues. In addition, I.V. administration of GNR to Ehrlich carcinoma tumor bearing mice resulted in similar tissue distribution; tumor accumulation and anti-tumor effect compared to intratumoral administration. In conclusion, the concentration of GNR achieved within tumors microregions after I.V. administration was comparable to I.T. administration and sufficient to elicit tumoral growth arrest when coupled with laser-aided photoplasmonic treatment.},
	isbn = {1932-6203},
	doi = {10.1371/journal.pone.0076207},
	author = {El-Sayed, M. A. and Shabaka, A. A. and El-Shabrawy, O. A. and Yassin, N. A. and Mahmoud, S. S. and El-Shenawy, S. M. and Al-Ashqar, E. and Eisa, W. H. and Farag, N. M. and El-Shaer, M. A. and Salah, N. and Al-Abd, A. M.}
}
@proceedings {1383,
	title = {Towards a perfect system for solar hydrogen production: an example of synergy on the atomic scale},
	year = {2013},
	pages = {88220A-88220A-7},
	publisher = {International Society for Optics and Photonics},
	author = {Nashed, Ramy and Alamgir, Faisal M and Seung-Soon, Jang and Ismail, Yehea and El-Sayed, Mostafa A. and Allam, Nageh}
}
@proceedings {1377,
	title = {Toxicities and antitumor efficacy of tumor-targeted AuNRs in mouse model},
	volume = {73},
	number = {8},
	year = {2013},
	publisher = {AMER ASSOC CANCER RESEARCH 615 CHESTNUT ST, 17TH FLOOR, PHILADELPHIA, PA 19106-4404 USA},
	isbn = {0008-5472},
	author = {Peng, Xianghong and Mackey, Megan and Austin, Lauren and Oyelere, Adegboyega and Chen, Georgia and Huang, Xiaohua and El-Sayed, Mostafa A. and Shin, Dong M}
}
@article {1331,
	title = {Aggregation and Interaction of Cationic Nanoparticles on Bacterial Surfaces},
	journal = {Journal of the American Chemical Society},
	volume = {134},
	number = {16},
	year = {2012},
	note = {Times Cited: 1Hayden, Steven C. Zhao, Gengxiang Saha, Krishnendu Phillips, Ronnie L. Li, Xiaoning Miranda, Oscar R. Rotello, Vincent M. El-Sayed, Mostafa A. Schmidt-Krey, Ingeborg Bunz, Uwe H. F.},
	month = {Apr},
	pages = {6920-6923},
	abstract = {Cationic monolayer-protected gold nanoparticles (AuNPs) with sizes of 6 or 2 nm interact with the cell membranes of Escherichia coli (Gram-) and Bacillus subtilis (Gram+), resulting in the formation of strikingly distinct AuNP surface aggregation patterns or lysis depending upon the size of the AuNPs. The aggregation phenomena were investigated by transmission electron microscopy and UV-vis spectroscopy. Upon proteolytic treatment of the bacteria, the distinct aggregation patterns disappeared.},
	isbn = {0002-7863},
	doi = {10.1021/ja301167y},
	author = {Hayden, S. C. and Zhao, G. X. and Saha, K. and Phillips, R. L. and Li, X. N. and Miranda, O. R. and Rotello, V. M. and El-Sayed, M. A. and Schmidt-Krey, I. and Bunz, U. H. F.}
}
@article {1339,
	title = {Different Methods of Increasing the Mechanical Strength of Gold Nanocages},
	journal = {Journal of Physical Chemistry Letters},
	volume = {3},
	number = {23},
	year = {2012},
	note = {Times Cited: 0Mahmoud, Mahmoud A. Szymanski, Paul El-Sayed, Mostafa A.},
	month = {Dec},
	pages = {3527-3531},
	abstract = {Using the ultrafast coherent modulation of the surface plasmon band intensity with the totally symmetric lattice vibration of gold nanocages, we were able to determine and use their frequencies as a measure of the cage{\textquoteright}s mechanical stability. The presence of an inner "stiff" transition-metal nanoshell with a higher value of the elastic modulus is found to increase the frequency of the lattice vibration of the outer soft gold nanoshell. This could also explain the observed increase in both the gold lattice vibrational frequency as well as the lattice vibration relaxation time in the Au-Pt and Au-Pd double-shell nanocages. It is also found that when these nanoparticles are assembled into monolayers on quartz substrates by the Langmuir-Blodgett technique, the oscillation frequency of the gold shell with the transition metal having the largest elastic constant suffers the least change in its oscillation frequency as a result of its resistance to distortion as a result of binding to the substrate.},
	isbn = {1948-7185},
	doi = {10.1021/jz301503z},
	author = {Mahmoud, M A and Szymanski, P. and El-Sayed, M. A.}
}
@article {1343,
	title = {Photoelectric Conversion Properties of Dye-Sensitized Solar Cells Using Dye-Dispersing Titania},
	journal = {Journal of Physical Chemistry C},
	volume = {116},
	number = {7},
	year = {2012},
	note = {Times Cited: 1Nishikiori, Hiromasa Uesugi, Yohei Setiawan, Rudi Agus Fujii, Tsuneo Qian, Wei El-Sayed, Mostafa A.},
	month = {Feb},
	pages = {4848-4854},
	abstract = {The time-resolved fluorescence and photoelectrochemical properties of dye-sensitized solar cells using crystalline titania electrodes coated with N3 dye-dispersing amorphous titania gel were investigated to clarify the influence of the dye titania interaction and electron transfer on their photoelectric conversion performance. The photocurrent quantum efficiency of the electrodes was remarkably increased by a steam treatment due to the crystallization and densification of the amorphous titania layer compared to that of the untreated electrode. The electron injection from the dye to the crystalline titania foundation via the steam-treated titania dispersing the dye was confirmed to be more efficient than that in the conventional electrodes. The dye-dispersing titania layer prevented interaction between the dye molecules and back electron transfer from the titania to the electrolyte. The charge separation and photoelectric conversion performance of the dye-sensitized solar cells were improved by forming the specific dye-dispersing titania layer.},
	isbn = {1932-7447},
	doi = {10.1021/jp2094388},
	author = {Nishikiori, H. and Uesugi, Y. and Setiawan, R. A. and Fujii, T. and Qian, W. and El-Sayed, M. A.}
}
@article {1344,
	title = {Some recent developments in photoelectrochemical water splitting using nanostructured TiO2: a short review},
	journal = {Theoretical Chemistry Accounts},
	volume = {131},
	number = {6},
	year = {2012},
	note = {Times Cited: 0Szymanski, Paul El-Sayed, Mostafa A.},
	month = {Jun},
	abstract = {Photoelectrochemical cells with TiO2 electrodes to convert sunlight and water into gaseous hydrogen and oxygen are a source of clean and renewable fuel. Despite their great potential, far-from-ideal performance and poor utilization of the solar spectrum have prevented them from becoming a widespread and practical technology. We review recent experimental work that uses dynamics measurements to study limitations of photoelectrochemical cells from a fundamental level and the use of TiO2 nanotube arrays as a superior alternative to TiO2 nanoparticles. Through a combination of nanoscale size control, doping, composite materials, and the incorporation of noble-metal nanoparticles, improved performance and light harvesting are demonstrated.},
	isbn = {1432-881X},
	doi = {10.1007/s00214-012-1202-2},
	author = {Szymanski, P. and El-Sayed, M. A.}
}
@article {1423,
	title = {Synthesis and Optical Properties of Small Au Nanorods Using a Seedless Growth Technique},
	journal = {Langmuir},
	volume = {28},
	year = {2012},
	month = {Jun},
	pages = {9807-9815},
	abstract = {Gold nanoparticles have shown potential in photothermal cancer therapy and optoelectronic technology. In both applications, a call for small size nanorods is warranted. In the present work, a one-pot seedless synthetic technique has been developed to prepare relatively small monodisperse gold nanorods with average dimensions (length x width) of 18 x 4.5 nm, 25 x 5 nm, 15 x 4.5 nm, and 10 x 2.5 nm. In this method, the pH was found to play a crucial role in the monodispersity of the nanorods when the NaBH4 concentration of the growth solution was adjusted to control the reduction rate of the gold ions. At the optimized pH and NaBH4 concentrations, smaller gold nanorods were produced by adjusting the CTAB concentration in the growth solution. In addition, the concentration of silver ions in the growth solution was found to be pivotal in controlling the aspect ratio of the nanorods. The extinction coefficient values for the small gold nanorods synthesized with three different aspect ratios were estimated using the absorption spectra, size distributions, and the atomic spectroscopic analysis data. The previously accepted relationships between the extinction coefficient or the longitudinal band wavelength values and the nanorods{\textquoteright} aspect ratios found for the large nanorods do not extend to the small size domain reported in the present work. The failure of extending these relationships over larger sizes is a result of the interaction of light with the large rods giving an extinction band which results mostly from scattering processes while the extinction of the small nanorods results from absorption processes.},
	isbn = {0743-7463},
	doi = {10.1021/la301387p},
	author = {Ali, M. R. K. and Snyder, B. and El-Sayed, M. A.}
}
@article {1324,
	title = {Synthesis and Optical Properties of Small Au Nanorods Using a Seedless Growth Technique},
	journal = {Langmuir},
	volume = {28},
	number = {25},
	year = {2012},
	note = {Times Cited: 2Ali, Moustafa R. K. Snyder, Brian El-Sayed, Mostafa A.},
	month = {Jun},
	pages = {9807-9815},
	abstract = {Gold nanoparticles have shown potential in photothermal cancer therapy and optoelectronic technology. In both applications, a call for small size nanorods is warranted. In the present work, a one-pot seedless synthetic technique has been developed to prepare relatively small monodisperse gold nanorods with average dimensions (length x width) of 18 x 4.5 nm, 25 x 5 nm, 15 x 4.5 nm, and 10 x 2.5 nm. In this method, the pH was found to play a crucial role in the monodispersity of the nanorods when the NaBH4 concentration of the growth solution was adjusted to control the reduction rate of the gold ions. At the optimized pH and NaBH4 concentrations, smaller gold nanorods were produced by adjusting the CTAB concentration in the growth solution. In addition, the concentration of silver ions in the growth solution was found to be pivotal in controlling the aspect ratio of the nanorods. The extinction coefficient values for the small gold nanorods synthesized with three different aspect ratios were estimated using the absorption spectra, size distributions, and the atomic spectroscopic analysis data. The previously accepted relationships between the extinction coefficient or the longitudinal band wavelength values and the nanorods{\textquoteright} aspect ratios found for the large nanorods do not extend to the small size domain reported in the present work. The failure of extending these relationships over larger sizes is a result of the interaction of light with the large rods giving an extinction band which results mostly from scattering processes while the extinction of the small nanorods results from absorption processes.},
	isbn = {0743-7463},
	doi = {10.1021/la301387p},
	author = {Ali, M. R. K. and Snyder, B. and El-Sayed, M. A.}
}
@article {1075,
	title = {Influence of Steam Treatment on Dye-Titania Complex Formation and Photoelectric Conversion Property of Dye-Doped Titania Gel},
	journal = {Journal of Physical Chemistry C},
	volume = {115},
	number = {6},
	year = {2011},
	note = {Nishikiori, Hiromasa Uesugi, Yohei Takami, Shohei Setiawan, RudiAgus Fujii, Tsuneo Qian, Wei El-Sayed, Mostafa A.},
	month = {Feb},
	pages = {2880-2887},
	abstract = {Xanthene dye molecules form a chelate complex with the titanium species on the titania surface in dye-titania systems. The complex formation causes a fast electron injection into the titania conduction band. In this study, simple spectroscopic and photocurrent measurements of the xanthene dye-doped titania gels prepared by the sol-gel method were conducted in order to clarify the influence of a steam treatment on the dye-titania interaction and electron transfer. The photocurrent quantum efficiency of the fluorescein-doped electrode was remarkably increased by the steam treatment compared to that of the untreated electrode consisting of an amorphous titania gel. The photocurrent action spectrum was red-shifted, and the short circuit photocurrent and open circuit voltage values increased with the steam treatment time. The steam treatment promoted the dye-titania complex formation, a negative shift in the conduction band potential of the titania, and the electron injection from the dye to the titania.},
	isbn = {1932-7447},
	doi = {10.1021/jp109958z},
	author = {Nishikiori, H. and Uesugi, Y. and Takami, S. and Setiawan, R. and Fujii, T. and Qian, Wei and El-Sayed, Mostafa A}
}
@article {1074,
	title = {Tailoring Plasmonic and Electrostatic Field Effects To Maximize Solar Energy Conversion by Bacteriorhodopsin, the Other Natural Photosynthetic System},
	journal = {Nano Letters},
	volume = {11},
	number = {9},
	year = {2011},
	note = {Yen, Chun-Wan Hayden, Steven C. Dreaden, Erik C. Szymanski, Paul El-Sayed, Mostafa A.},
	month = {Sep},
	pages = {3821-3826},
	abstract = {We have explored the plasmonic field enhancement of current production from bacteriorhodopsin (bR) by maximizing the blue light effect, where the influx of blue photons absorbed by the long-lived M intermediate drastically shortens the time scale of the bR photocycle, leading to current enhancement. To this end, we used three approaches in our solution-based cell: proton selective Nafion membrane. (2) We maximized the plasmonic surface (1) We improved the charge carrier separation in solution through the use of a field effects by selecting the capping polymer with minimum surface field screening and best nanopartide stability. (3) We selected the plasmonic nanoparticle with the strongest plasmonic field whose surface plasmon resonance has the largest spectral overlap with the blue light absorbing M-intermediate. Theoretical models are used to explain experimental results, which show a 40 nm cuboidal nanoparticle capped with 55k PVP polymer to give the best photocurrent enhancement. Enhanced by this particle, bR in our Nafion membrane solution cell gave a photocurrent of 0.21 mu A/cm(3), which is 5000 times larger than the published results for thin film bR electrochemical cells even with an applied bias. Additional possible enhancements are proposed.},
	isbn = {1530-6984},
	doi = {10.1021/nl2018959},
	author = {Yen, C. W. and Hayden, S. C. and Dreaden, Erik and Szymanski, P. and El-Sayed, Mostafa A}
}
@article {1092,
	title = {Experimental Evidence For The Nanocage Effect In Catalysis With Hollow Nanoparticles},
	journal = {Nano Letters},
	volume = {10},
	number = {9},
	year = {2010},
	note = {Mahmoud, M. A. Saira, F. El-Sayed, M. A.},
	month = {Sep},
	pages = {3764-3769},
	abstract = {Five different hollow cubic nanoparticles with wall length of 75 nm Were synthesized from platinum and/or palladium elements. The five nanocatalysts are pure platinum nanocages (PtNCs), pure palladium :nanocages (PdNCs), Pt/Pd hollow shell-shell nanocages (NCs) (where Pd is defined as the inner shell around the cavity) Pd/Pt shell-shell NCs, and Pt-Pd alloy NCs. These are used to catalyze the reduction of 4-nitrophenol with sodium borohydride. The kinetic parameters (rate constants, activation energies, frequency factors, and entropies of activation) of each shell/shell NCs are found to be comparable to that of pure metal NCs made of the same metal coating the cavity in the shell-shell NCs. These results strongly Suggest that the catalytic reaction takes place inside the cavity of the hollow nanoparticles. Because of the nanoreactor confinement effect of the hollow nanocatalysts, the frequency factors obtained from the Arrhenius plots are found to be the highest ever reported for this reduction reaction. This is the reason for enhanced rate of this reaction inside the cavity. The importance of mechanism of the homogeneous and the heterogeneous nanocatalytic reactions occurring on the external surface of a solid nanoparticle are contrasted with those occurring on the nanocavity surface.},
	isbn = {1530-6984},
	doi = {10.1021/nl102497u},
	author = {Mahmoud, M A and Saira, F. and El-Sayed, Mostafa A}
}
@article {1091,
	title = {Polystyrene Microspheres: Inactive Supporting Material for Recycling and Recovering Colloidal Nanocatalysts in Solution},
	journal = {Journal of Physical Chemistry Letters},
	volume = {1},
	number = {1},
	year = {2010},
	note = {Mahmoud, M. A. Snyder, B. El-Sayed, M. A.},
	month = {Jan},
	pages = {28-31},
	abstract = {Alumina and silica have been the most commonly, used solid supports in the recovery of colloidal nanocatalysts in solution. In order to avoid possible involvement of the support in the catalytic mechanism, polystyrene microspheres are here demonstrated to be effective and nonreactive supports on which the nanocatalyst can be easily attached by using the swelling and shrinking properties of the polystyrene microspheres. The activation energy of the reduction of 4-nitrophenol with sodium borohydride on platinum nanocubes free in solution is comparable to those on polystyrene microspheres.},
	isbn = {1948-7185},
	doi = {10.1021/jz9000449},
	author = {Mahmoud, M A and Snyder, B. and El-Sayed, Mostafa A}
}
@article {808,
	title = {A Reexamination of Active and Passive Tumor Targeting by Using Rod-Shaped Gold Nanocrystals and Covalently Conjugated Peptide Ligands},
	journal = {ACS Nano},
	volume = {4},
	year = {2010},
	note = {doi: 10.1021/nn102055s},
	month = {2010},
	pages = {5887 - 5896},
	publisher = {American Chemical Society},
	abstract = {The targeted delivery of nanoparticles to solid tumors is one of the most important and challenging problems in cancer nanomedicine, but the detailed delivery mechanisms and design principles are still not well understood. Here we report quantitative tumor uptake studies for a class of elongated gold nanocrystals (called nanorods) that are covalently conjugated to tumor-targeting peptides. A major advantage in using gold as a ?tracer? is that the accumulated gold in tumors and other organs can be quantitatively determined by elemental mass spectrometry (gold is not a natural element found in animals). Thus, colloidal gold nanorods are stabilized with a layer of polyethylene glycols (PEGs) and are conjugated to three different ligands: (i) a single-chain variable fragment (ScFv) peptide that recognizes the epidermal growth factor receptor (EGFR); (ii) an amino terminal fragment (ATF) peptide that recognizes the urokinase plasminogen activator receptor (uPAR); and (iii) a cyclic RGD peptide that recognizes the av?3 integrin receptor. Quantitative pharmacokinetic and biodistribution data show that these targeting ligands only marginally improve the total gold accumulation in xenograft tumor models in comparison with nontargeted controls, but their use could greatly alter the intracellular and extracellular nanoparticle distributions. When the gold nanorods are administered via intravenous injection, we also find that active molecular targeting of the tumor microenvironments (e.g., fibroblasts, macrophages, and vasculatures) does not significantly influence the tumor nanoparticle uptake. These results suggest that for photothermal cancer therapy, the preferred route of gold nanorod administration is intratumoral injection instead of intravenous injection.The targeted delivery of nanoparticles to solid tumors is one of the most important and challenging problems in cancer nanomedicine, but the detailed delivery mechanisms and design principles are still not well understood. Here we report quantitative tumor uptake studies for a class of elongated gold nanocrystals (called nanorods) that are covalently conjugated to tumor-targeting peptides. A major advantage in using gold as a ?tracer? is that the accumulated gold in tumors and other organs can be quantitatively determined by elemental mass spectrometry (gold is not a natural element found in animals). Thus, colloidal gold nanorods are stabilized with a layer of polyethylene glycols (PEGs) and are conjugated to three different ligands: (i) a single-chain variable fragment (ScFv) peptide that recognizes the epidermal growth factor receptor (EGFR); (ii) an amino terminal fragment (ATF) peptide that recognizes the urokinase plasminogen activator receptor (uPAR); and (iii) a cyclic RGD peptide that recognizes the av?3 integrin receptor. Quantitative pharmacokinetic and biodistribution data show that these targeting ligands only marginally improve the total gold accumulation in xenograft tumor models in comparison with nontargeted controls, but their use could greatly alter the intracellular and extracellular nanoparticle distributions. When the gold nanorods are administered via intravenous injection, we also find that active molecular targeting of the tumor microenvironments (e.g., fibroblasts, macrophages, and vasculatures) does not significantly influence the tumor nanoparticle uptake. These results suggest that for photothermal cancer therapy, the preferred route of gold nanorod administration is intratumoral injection instead of intravenous injection.},
	isbn = {1936-0851},
	url = {http://dx.doi.org/10.1021/nn102055s},
	author = {Huang, Xiaohua and Peng, Xianghong and Wang, Yiqing and Wang, Yuxiang and Shin, Dong M and El-Sayed, Mostafa A and Nie, Shuming}
}
@article {1090,
	title = {Surface Plasmon Fields and Coupling in the Hollow Gold Nanoparticles and Surface-Enhanced Raman Spectroscopy. Theory and Experiment},
	journal = {Journal of Physical Chemistry C},
	volume = {114},
	number = {16},
	year = {2010},
	note = {Mahmoud, M. A. Snyder, B. El-Sayed, M. A.},
	month = {Apr},
	pages = {7436-7443},
	abstract = {Most gold nanoparticles have surface plasmon fields only surrounding their surfaces. Recently, hollow nanoparticles have been studied, such as gold nanocages (AuNC) and gold nanoframes (ALINE). Those particles have two types of surfaces, one facing the outside and the other within the cavity. Their coupling provides a surface field inside the hollow particle and on the outside surface. Using DDA computational method, we have shown that the coupling between these fields gives field intensities and distribution inside and outside the nanoparticles that are sensitive to the thickness (the distance between the two surfaces) as well as the nanoparticle size. For small sizes, the coupling between the fields on the opposite sides of the cage is detected. These effects are detected by following the changes in the experimentally observed surface plasmon resonance spectra of these nanoparticles and the surface-enhanced Raman spectra of adsorbed molecules. The effect of the interaction between the external and internal field as well as the available surface area inside and outside the nanoparticle effects on the Raman-enhancement is detected by comparing the Raman intensities dependence on the interparticle distance with those observed on solid nanocubes surfaces.},
	isbn = {1932-7447},
	doi = {10.1021/jp9109018},
	author = {Mahmoud, M A and Snyder, B. and El-Sayed, Mostafa A}
}
@article {1118,
	title = {Tamoxifen-Poly(ethylene glycol)-Thiol Gold Nanoparticle Conjugates: Enhanced Potency and Selective Delivery for Breast Cancer Treatment},
	journal = {Bioconjugate Chemistry},
	volume = {20},
	number = {12},
	year = {2009},
	note = {Dreaden, Erik C. Mwakwari, Sandra C. Sodji, Quaovi H. Oyelere, Adegboyega K. El-Sayed, Mostafa A.},
	month = {Dec},
	pages = {2247-2253},
	abstract = {The breast cancer treatment drug tamoxifen has been widely administered for more than three decades. This small molecule competes with 17 beta-estradiol for binding to estrogen receptor, a hormone receptor upregulated in a majority of breast cancers, Subsequently initiating programmed cell death. We have synthesized a thiol-PEoylated tamoxifen derivative that can be used to selectively target and deliver plasmonic gold nanoparticles to estrogen receptor positive breast cancer cells with tip to 2.7-fold enhanced drug potency in vitro. Optical microscopy/spectroscopy, tirne-dependent dose-response data, and estrogen competition studies indicate that augmented activity is due to increased rates of intracellular tamoxifen transport by nanoparticle endocytosis, rather than by passive diffusion of the free drug. Both ligand- and receptor-dependent intracellular delivery of gold nanoparticles suggest that plasma membrane localized estrogen receptor alpha may facilitate selective uptake and retention of this and other therapeutic nanoparticle conjugates. Combined targeting selectivity and enhanced potency provides opportunities for both multimodal endocrine treatment strategies and adjunctive laser photothermal therapy.},
	isbn = {1043-1802},
	doi = {10.1021/bc9002212},
	author = {Dreaden, Erik and Mwakwari, S. C. and Sodji, Q. H. and Oyelere, A. K. and El-Sayed, Mostafa A}
}
@article {1293,
	title = {Effect of crystallization on the proton pump function of bR},
	journal = {ISRAPS Bulletin},
	volume = {18},
	year = {2006},
	pages = {52-57},
	author = {Sanii, L. S. and El-Sayed, Mostafa A}
}
@article {1146,
	title = {Ultrafast electronic relaxation and charge-carrier localization in CdS/CdSe/CdS quantum-dot quantum-well heterostructures},
	journal = {Nano Letters},
	volume = {6},
	number = {9},
	year = {2006},
	note = {Schill, Alexander W. Gaddis, Christopher S. Qian, Wei El-Sayed, Mostafa A. Cai, Ye Milam, Valeria T. Sandhage, Kenneth},
	month = {Sep},
	pages = {1940-1949},
	abstract = {The relaxation and localization times of excited electrons in CdS/CdSe/CdS colloidal quantum wells were measured using subpicosecond spectroscopy. HRTEM analysis and steady-state PL demonstrate a narrow size distribution of 5-6 nm epitaxial crystallites. By monitoring the rise time of the stimulated emission as a function of pump intensity, the relaxation times of the electron from the CdS core into the CdSe well are determined and assigned. Two-component rise times in the stimulated emission are attributed to intraband relaxation of carriers generated directly within the CdSe well ( fast component) and charge transfer of core-localized carriers across the CdS/CdSe interface ( slow component). This is the first reported observation of simultaneous photon absorption in the core and well of a quantum-dot heterostructure. With increasing pump intensity, the charge-transfer channel between the CdS core CdSe well contributes less to the stimulated emission signal because of filling and saturation of the CdSe well state, making the interfacial charge-transfer component less efficient. The interfacial charge-transfer time of the excited electron was determined from the slow component of the stimulated emission build-up time and is found to have a value of 1.2 ps.},
	isbn = {1530-6984},
	doi = {10.1021/nl061054v},
	author = {Schill, A. W. and Gaddis, C. S. and Qian, Wei and El-Sayed, Mostafa A and Cai, Y. and Milam, V. T. and Sandhage, K.}
}
@article {1155,
	title = {Using silica films and powders modified with benzophenone to photoreduce silver nanoparticles},
	journal = {Journal of Photochemistry and Photobiology a-Chemistry},
	volume = {181},
	number = {2-3},
	year = {2006},
	note = {Eustis, Susie Krylova, Galina Smirnova, Natalie Eremenko, Anna Tabor, Christopher Huang, Wenyu El-Sayed, Mostafa A.},
	month = {Jul},
	pages = {385-393},
	abstract = {Porous silica (SiO2 films and powders), modified with benzophenone (BP), facilitates the formation of stable sliver nanoparticles by taking advantage of the solid supported photosensitizer. The silica serves as a carrier for the BP into an aqueous solution and its subsequent removal. Benzophenone, bound to a silica film, was able to reduce silver ions to generate nanoparticles in solution, while silica powder with bound BP generates silver nanoparticles that are attracted to the silica. Silver nanoparticles are also fabricated in porous silica films by incorporating silver ions into the films before casting and then irradiating the film in a solution containing BP. From pH studies, it is concluded that the ketyl-radicals and anion-radicals of BP and IPA both take part in the reduction of silver ions. These synthetic studies provide a new photochemical reduction method by immobilizing the reactant on a silica surface allowing generation of silver nanoparticles in solution attached to powders or inside a film for catalytic applications or increased conductivity of silica films. (c) 2006 Elsevier B.V. All rights reserved.},
	isbn = {1010-6030},
	doi = {10.1016/j.jphotochem.2005.12.024},
	author = {Eustis, Susie and Krylova, G. and Smirnova, N. and Eremenko, A. and Tabor, C. E. and Huang, Wenyu and El-Sayed, Mostafa A}
}
@article {837,
	title = {Growth and fragmentation of silver nanoparticles in their synthesis with a fs laser and CW light by photo-sensitization with benzophenone},
	journal = {Photochemical \& Photobiological Sciences},
	volume = {4},
	year = {2005},
	pages = {154-159},
	publisher = {Royal Society of Chemistry},
	abstract = {The photo-sensitization synthetic technique of making silver nanoparticles using benzophenone is studied using both a laser and a mercury lamp as light sources. The power and irradiation time dependence of the synthesized nanoparticle absorption spectra and their size distribution [as determined by transmission electron microscopy (TEM)] are studied in each method and compared. In the laser synthesis, as either the laser power or the irradiation time increases, the intensity of the surface plasmon resonance absorption at 400 nm is found to increase linearly first, followed by a reduction of the red edge of the plasmon resonance absorption band. The TEM results showed that in the laser synthesis low powers and short irradiation times produce nanoparticles around 20 nm in diameter. Increasing the power or irradiation time produces a second population of nanoparticles with average size of 5 nm in diameter. These small particles are believed to be formed from the surface ablation of the large particles. The surface plasmon absorption band is found to be narrower when the nanoparticles are produced with laser irradiation. Throughout the exposure time with the CW lamp, the plasmon resonance absorption band of the particles formed first grows in intensity, then blue shifts and narrows, and finally red shifts while decreasing in intensity. The TEM results for lamp samples showed particle formation and growth, followed by small nanoparticle formation. The above results are discussed in terms of a mechanism in which, the excited benzophenone forms the ketal radical, which reduces Ag+ in solution and on the Ag nanoparticle surface. As the time of irradiation or the light energy increases the benzophenone is consumed, which is found to be the limiting reagent. This stops the formation of the normal large nanoparticles while their photo-ablation continues to make the small particles.},
	doi = {10.1039/B411488D},
	author = {Eustis, Susie and Krylova, G. and Eremenko, A. and Smirnova, N. and Schill, A. W. and El-Sayed, Mostafa A}
}
@article {1163,
	title = {Partial dehydration of the retinal binding pocket and proof for photochemical deprotonation of the retinal Schiff base in bicelle bacteriorhodopsin crystals},
	journal = {Photochemistry and Photobiology},
	volume = {81},
	number = {6},
	year = {2005},
	note = {Sanii, LS El-Sayed, MA},
	month = {Nov-Dec},
	pages = {1356-1360},
	abstract = {In bicelle bacteriorhodopsin (bcbR) crystals, the protein has a different structure from both native bacteriorhodopsin (bR) and in-cubo bR (cbR) crystals. Recently, we studied the ability of bcbR crystals to undergo the photocycle upon laser excitation, characterized by the appearance of the M intermediate by single crystal resonance Raman spectroscopy. Calculation of the M lifetime by flash photolysis experiments demonstrated that in our bchR crystals, the M rise time is much faster than in the native or cbR crystals, with a decay time that is much slower than these other two forms. Although it is now known that the bcbR crystals are capable of photochemical deprotonation, it is not known whether photochemical deprotonation is the only way to create the deprotonated Schiff base in the bcbR crystals. We measured both the visible and Raman spectra of crystals dried under ambient lighting and dried in the dark in order to determine whether the retinal Schiff base is able to thermally deprotonate in the dark. In addition, changes in the visible spectrum of single bcbR crystals under varying degrees of hydration and light exposure were examined to better understand the retinal binding environment.},
	isbn = {0031-8655},
	doi = {10.1562/2005-03-09-ra-458},
	author = {Sanii, L. S. and El-Sayed, Mostafa A}
}
@article {1162,
	title = {The protonation-deprotonation kinetics of the protonated Schiff base in bicelle bacteriorhodopsin crystals},
	journal = {Biophysical Journal},
	volume = {89},
	number = {1},
	year = {2005},
	note = {Sanii, LS Schill, AW Moran, CE El-Sayed, MA},
	month = {Jul},
	pages = {444-451},
	abstract = {In the recently published x-ray crystal structure of the "bicelle" bacteriorhodopsin (bbR) crystal, the protein has quite a different structure from the native and the in cubo bacteriorhodopsin (cbR) crystal. Instead of packing in parallel trimers as do the native membrane and the cbR crystals, in the bbR crystal the protein packs as antiparallel monomers. To date, no functional studies have been performed, to our knowledge, to investigate if the photocycle is observed in this novel protein packing structure. In this study, both Raman and time-resolved transient absorption spectroscopy are used to both confirm the presence of the photocycle and investigate the deprotonation-reprotonation kinetics of the Schiff base proton in the bbR crystal. The observed rates of deprotonation and reprotonation processes of its Schiff base have been compared to those observed for native bR under the same conditions. Unlike the previously observed similarity of the rates of these processes for cbR crystals and those for native bacteriorhodopsin (bR), in bbR crystals the rate of deprotonation has increased by 300\%, and the rate of reprotonation has decreased by nearly 700\%. These results are discussed in light of the changes observed when native bR is delipidated or monomerized by detergents. Both the change of the hydrophobicity of the environment around the protonated Schiff base and Asp(85) and Asp(96) (which could change the pK(a) values of proton donor-acceptor pairs) and the water structure in the bbR crystal are offered as possible explanations for the different observations.},
	isbn = {0006-3495},
	doi = {10.1529/biophysj.105.059675},
	author = {Sanii, L. S. and Schill, A. W. and Moran, C. E. and El-Sayed, Mostafa A}
}
@article {1183,
	title = {Model system for growing and quantifying Streptococcus pneumoniae biofilms in situ and in real time},
	journal = {Applied and Environmental Microbiology},
	volume = {70},
	number = {8},
	year = {2004},
	note = {Donlan, RM Piede, JA Heyes, CD Sanii, L Murga, R Edmonds, P El-Sayed, I El-Sayed, MA},
	month = {Aug},
	pages = {4980-4988},
	abstract = {Streptococcus pneumoniae forms biofilms, but little is known about its extracellular polymeric substances (EPS) or the kinetics of biofilm formation. A system was developed to enable the simultaneous measurement of cells and the EPS of biofilm-associated S. pneumoniae in situ over time. A biofilm reactor containing germanium coupons was interfaced to an attenuated total reflectance (ATR) germanium cell of a Fourier transform infrared (FTIR) laser spectrometer. Biofilm-associated cells were recovered from the coupons and quantified by total and viable cell count methods. ATR-FTIR spectroscopy of biofilms formed on the germanium internal reflection element (IRE) of the ATR cell provided a continuous spectrum of biofilm protein and polysaccharide (a measure of the EPS). Staining of the biofilms on the IRE surface with specific fluorescent probes provided confirmatory evidence for the biofilm structure and the presence of biofilm polysaccharides. Biofilm protein and polysaccharides were detected within hours after inoculation and continued to increase for the next 141 h. The polysaccharide band increased at a substantially higher rate than did the protein band, demonstrating increasing coverage of the IRE surface with biofilm polysaccharides. The biofilm total cell counts on germanium coupons stabilized after 21 h, at approximately 10(5) cells per cm(2), while viable counts decreased as the biofilm aged. This system is unique in its ability to detect and quantify biofilm-associated cells and EPS of S. pneumoniae over time by using multiple, corroborative techniques. This approach could prove useful for the study of biofilm processes of this or other microorganisms of clinical or industrial relevance.},
	isbn = {0099-2240},
	doi = {10.1128/aem.70.8.4980-4988.2004},
	author = {Donlan, R. M. and Piede, J. A. and Heyes, C D and Sanii, L. S. and Murga, R. and Edmonds, P. and El Sayed, I.H. and El-Sayed, Mostafa A}
}
@article {1174,
	title = {Wavelength-dependent hot electron relaxation in PVP capped CdS/HgS/CdS quantum dot quantum well nanocrystals},
	journal = {Journal of Physical Chemistry B},
	volume = {108},
	number = {36},
	year = {2004},
	note = {Schill, AW El-Sayed, MA},
	month = {Sep},
	pages = {13619-13625},
	abstract = {Subpicosecond pump-probe transient absorption spectroscopy has been used to examine the probe wavelength-dependent kinetics of PVP capped CdS/HgS/CdS quantum dot quantum well nanoparticles. Using 398- and 520-nm excitations, the relaxation of the excited hot electrons above the band gap state is characterized by both rapid electronic nonradiative relaxation and slower thermal relaxation processes. The wavelength dependence of both the fast rise and fast decay of the transient bleach is discussed in terms of electronic relaxation processes involving mixed CdS/HgS states at short probe wavelengths or pure HgS states at long probe wavelengths. The slow decay of the transient bleach is discussed in terms of a thermal relaxation process leading to the dissipation of heat from the hot nanoparticle lattice to the surrounding medium.},
	isbn = {1520-6106},
	doi = {10.1021/jp047832u},
	author = {Schill, A. W. and El-Sayed, Mostafa A}
}
@article {1189,
	title = {Why is the thermalization of excited electrons in semiconductor nanoparticles so rapid? Studies on CdSe nanoparticles},
	journal = {Chemical Physics Letters},
	volume = {373},
	number = {3-4},
	year = {2003},
	note = {Darugar, Q Landes, C Link, S Schill, A El-Sayed, MA},
	month = {May},
	pages = {284-291},
	abstract = {Quantum confinement of electronic motion in semiconductor nanoparticles leads to quantization of its band continua of the bulk. The relaxation between the resulting quantized levels by electron phonon coupling was expected, but not found, to be slow due to the small phonon frequencies (phonon bottleneck). Studying the electronic relaxation from the band gap and a higher excited state in CdSe dots and rods under different perturbations suggest the importance of coupling the excited electron to the surface. The surface species act as an efficient heat bath or as electron trapping sites in the linear or nonlinear (Auger) relaxation processes. (C) 2003 Elsevier Science B.V. All rights reserved.},
	isbn = {0009-2614},
	doi = {10.1016/s0009-2614(03)00213-6},
	author = {Darugar, Q. and Landes, Christy F. and Link, Stephan and Schill, A. W. and El-Sayed, Mostafa A}
}
@article {851,
	title = {Fourier transform infrared study of the effect of different cations on bacteriorhodopsin protein thermal stability},
	journal = {Biophysical journal},
	volume = {82},
	year = {2002},
	pages = {1598-1606},
	publisher = {Elsevier},
	abstract = {The effect of divalent ion binding to deionized bacteriorhodopsin (dI-bR) on the thermal transitions of the protein secondary structure have been studied by using temperature-dependent Fourier transform infrared (FT-IR) spectroscopy. The native metal ions in bR, Ca2+, and Mg2+, which we studied previously, are compared with Mn2+, Hg2+, and a large, synthesized divalent organic cation, ((Et)3N)2Bu2+. It was found that in all cases of ion regeneration, there is a pre-melting, reversible conformational transition in which the amide frequency shifts from 1665 to 1652cm-1. This always occurs at \~{}80{\textdegree}C, independent of which cation is used for the regeneration. The irreversible thermal transition (melting), monitored by the appearance of the band at 1623cm-1, is found to occur at a lower temperature than that for the native bR but higher than that for acid blue bR in all cases. However, the temperature for this transition is dependent on the identity of the cation. Furthermore, it is shown that the mechanism of melting of the organic cation regenerated bR is different than for the metal cations, suggesting a difference in the type of binding to the protein (either to different sites or different binding to the same site). These results are used to propose specific direct binding mechanisms of the ions to the protein of deionized bR.},
	isbn = {0006-3495},
	doi = {10.1016/S0006-3495(02)75511-2},
	url = {http://dx.doi.org/10.1016/S0006-3495(02)75511-2},
	author = {Heyes, C D and Wang, Jianping and Sanii, L. S. and El-Sayed, Mostafa A}
}
@article {1197,
	title = {Transition from nanoparticle to molecular behavior: a femtosecond transient absorption study of a size-selected 28 atom gold cluster},
	journal = {Chemical Physics Letters},
	volume = {356},
	number = {3-4},
	year = {2002},
	note = {Link, S El-Sayed, MA Schaaff, TG Whetten, RL},
	month = {Apr},
	pages = {240-246},
	abstract = {The ultrafast electron dynamics of chemically prepared gold nanoclusters with a 28 atom gold core surrounded by 16 glutathione molecules were investigated. After excitation with femtosecond laser pulses these clusters show an induced transient absorption in the visible from 2.58 to 1.65 eV (480-750 nm) with a maximum around 2.07 eV (600 nm). The excited state relaxation shows a biexponential decay with a subpicosecond and a longer nanosecond decay time independent of the laser pump power. These results are different from those observed previously for larger gold nanoparticles, which suggests that the Au-28-glutathione system shows molecular properties. (C) 2002 Elsevier Science B.V. All rights reserved.},
	isbn = {0009-2614},
	doi = {10.1016/s0009-2614(02)00306-8},
	author = {Link, Stephan and El-Sayed, Mostafa A and Schaaff, T. G. and Whetten, R. L.}
}
@article {1199,
	title = {Visible to infrared luminescence from a 28-atom gold cluster},
	journal = {Journal of Physical Chemistry B},
	volume = {106},
	number = {13},
	year = {2002},
	note = {Link, S Beeby, A FitzGerald, S El-Sayed, MA Schaaff, TG Whetten, RL},
	month = {Apr},
	pages = {3410-3415},
	abstract = {The luminescence properties of chemically prepared gold nanoclusters, each composed of a 28-atom core and a glutathione (GSH) adsorbate layer consisting of 16 molecules, were investigated. These clusters show a distinct absorption onset at 1.3 eV corresponding to the opening of an electronic gap within the conduction band (HOMO-LUMO gap). Here we report on the radiative properties of these molecular-like Bald clusters. By using a combination of different detectors with sensitivities in the visible to the infrared (2.0-0.8 eV), a broad luminescence extending over this entire spectral range was observed. Our results further suggest that the luminescence can be separated into two bands with maxima around 1.5 and 1.15 eV indicating that radiative recombination between the ground state and two distinctively different excited states takes place. The: origin of the observed luminescence bands is discussed using a solid state as well as a molecular model for the electronic structure and relaxation of the clusters. The total quantum yield of the luminescence: as measured at ambient temperature was approximated to be about (3.5 +/- 1.0) x 10(-3).},
	isbn = {1520-6106},
	doi = {10.1021/jp014259v},
	author = {Link, Stephan and Beeby, A. and FitzGerald, S. and El-Sayed, Mostafa A and Schaaff, T. G. and Whetten, R. L.}
}
@article {1237,
	title = {Time-resolved Fourier-transform infrared and visible luminescence spectroscopy of photoexcited porous silicon},
	journal = {Physical Review B},
	volume = {59},
	number = {7},
	year = {1999},
	note = {Wang, JP Song, L Zou, BS El-Sayed, MA},
	month = {Feb},
	pages = {5026-5031},
	abstract = {In order to identify the luminescent centers in aged porous silicon, both the time-resolved vibration spectra in the 750-2000-cm(-1) region and the visible luminescence spectra are studied for the same sample in the 0-440-mu s time domain. Laser excitation gives rise to emission characteristics of the porous silicon as well as strong bleach in the infrared spectrum in the region of the ground-stale silicon-oxygen stretching vibration frequencies at 1100 and 1235 cm(-1). In addition, new transient absorption bands appear in this region as a result of the laser excitation. Three characteristic Lifetimes in the decay of the bleach band at 1235 cm(-1) are observed on the 1-, 10-, and 100-mu s time scale. These are similar to the observed decay times of the photoluminescence from porous silicon. These results suggest that the emitting centers in aged porous silicon are trapped excitation sites in an inhomogeneously defected oxidized silicon surface. [S0163-1829(99)09207-3].},
	isbn = {0163-1829},
	doi = {10.1103/PhysRevB.59.5026},
	author = {Wang, Jianping and Song, Li and Zou, Bingsuo and El-Sayed, Mostafa A}
}
@article {1250,
	title = {Application of liquid waveguide to Raman spectroscopy in aqueous solution},
	journal = {Applied Spectroscopy},
	volume = {52},
	number = {10},
	year = {1998},
	note = {Song, L Liu, SY Zhelyaskov, V El-Sayed, MA},
	month = {Oct},
	pages = {1364-1367},
	isbn = {0003-7028},
	author = {Song, Li and Liu, S. Y. and Zhelyaskov, V. and El-Sayed, Mostafa A}
}
@article {1251,
	title = {Primary step in bacteriorhodopsin photosynthesis: Bond stretch rather than angle twist of its retinal excited-state structure},
	journal = {Journal of the American Chemical Society},
	volume = {120},
	number = {34},
	year = {1998},
	note = {Song, L El-Sayed, MA},
	month = {Sep},
	pages = {8889-8890},
	isbn = {0002-7863},
	doi = {10.1021/ja980390d},
	author = {Song, Li and El-Sayed, Mostafa A}
}
@article {1259,
	title = {A Comparison of the Photoelectric Current Responses Resulting from the Proton Pumping Process of Bacteriorhodopsin under Pulsed and CW Laser Excitations},
	journal = {The Journal of Physical Chemistry B},
	volume = {101},
	year = {1997},
	note = {doi: 10.1021/jp972475r},
	month = {1997},
	pages = {10599 - 10604},
	publisher = {American Chemical Society},
	abstract = {When excited with a pulsed laser, an electric field-oriented bacteriorhodopsin (bR) film on an indium-tin oxide (ITO) conductive electrode generates a photocurrent composed of at least three different components:  B1 (<100 ps), B2 (60 μs), and B3 (ms). When excited with an electronic shutter modulated CW light pulse (>200 ms in duration), a differential photocurrent (components D1 and D2 with decay times in milliseconds) is observed from the bR film. D1 is observed when the CW light is turned on, and D2 is observed when the CW light is turned off. In this paper, we compare the amplitudes and lifetimes of B2, B3, and D1 at various values of pH and ionic strength of the electrolyte solution in which the photocurrent is measured. It is found that changing the film orientation changes the polarity (sign) of B1 and B2, while it does not affect the polarity of B3 and D1. It is also found that B3 and D1 change their polarity upon changing the pH of electrolyte solution, whereas B1 and B2 do not. These results suggest that the origin of B3 and D1 is different from that of B1 and B2. Our results suggest that B3 and D1 are due to the formation of a transient proton capacitor between the two ITO electrodes resulting from the proton pumping in bR. The magnitude and sign of B3 and D1 are determined by the transient proton concentration change (accumulation or disappearance) occurring near the bR-modified ITO electrode interface on the millisecond time scale. The change of sign in B3 and D1 as a function of pH is due to the sequence of proton release/uptake in the bR photocycle:  It first releases protons into the aqueous solution at high pH, while it first takes up protons from the aqueous solution at low pH. The effects of buffer and ionic strength on B3 and D1 are discussed in terms of the kinetics of proton release/uptake and of the transportation of positive and negative ions in the electrolyte solution.},
	isbn = {1520-6106},
	url = {http://dx.doi.org/10.1021/jp972475r},
	author = {Wang, Jianping and Song, Li and Yoo, Seoung-Kyo and El-Sayed, Mostafa A}
}
@article {874,
	title = {Molecular Mechanism of the Differential Photoelectric Response of Bacteriorhodopsin},
	journal = {The Journal of Physical Chemistry B },
	volume = {101},
	year = {1997},
	note = {doi: 10.1021/jp962111j},
	month = {1997},
	pages = {3420 - 3423},
	publisher = {American Chemical Society},
	abstract = {In order to determine the molecular origin of the differential photocurrent from bacteriorhodopsin (bR), the photoelectric response of bR film deposited on an indium tin oxide (ITO) conductive glass electrode under CW excitation is compared with that under pulsed laser excitation at different pH and with opposite membrane orientation with respect to the ITO electrode surface. The characteristics (sign and magnitude) of the dominant component of the differential photocurrent (appearing on the millisecond time scale) are found to correlate with the process of proton release into, or uptake from, the aqueous solution during the photocycle under different experimental conditions. This suggests that the differential current results mainly from the change in the H+ concentration at the bR?ITO electrode interface.In order to determine the molecular origin of the differential photocurrent from bacteriorhodopsin (bR), the photoelectric response of bR film deposited on an indium tin oxide (ITO) conductive glass electrode under CW excitation is compared with that under pulsed laser excitation at different pH and with opposite membrane orientation with respect to the ITO electrode surface. The characteristics (sign and magnitude) of the dominant component of the differential photocurrent (appearing on the millisecond time scale) are found to correlate with the process of proton release into, or uptake from, the aqueous solution during the photocycle under different experimental conditions. This suggests that the differential current results mainly from the change in the H+ concentration at the bR?ITO electrode interface.},
	isbn = {1520-6106},
	url = {http://dx.doi.org/10.1021/jp962111j},
	author = {Wang, Jianping and Yoo, Seoung-Kyo and Song, Li and El-Sayed, Mostafa A}
}
@article {864,
	title = {Optical rotation of the second harmonic radiation from retinal in bacteriorhodopsin monomers in Langmuir-Blodgett film: evidence for nonplanar retinal structure.},
	journal = {Biophysical journal},
	volume = {73},
	year = {1997},
	month = {1997 Dec},
	pages = {3164-70},
	abstract = {We observed optical rotation of the plane of polarization of the second harmonic (SH) radiation at 532 nm (in resonance with the retinal absorption) generated in reflection geometry in Langmuir-Blodgett film of bacteriorhodopsin (bR). The analysis of the experimental data showed that this effect arises from the nonvanishing contribution of the antisymmetrical part of the hyperpolarizability tensor. This requires that the dipole moment of the resonant electronic transition, the change of the dipole moment upon electronic excitation, and the long axis of the retinal not be coplanar. Such conditions are satisfied only if the retinal has a nonplanar geometry, a conclusion that could lend support to the heterogeneity model of the origin of the biphasic band shape of the linear CD spectrum of the retinal in bR. On the basis of our theoretical analysis, we were able to estimate the angle between the induced dipole moment and the plan that contains the long axis of the chromophore and the transition dipole moment of the retinal absorption.},
	keywords = {Bacteriorhodopsins, Biophysical Phenomena, Biophysics, Circular Dichroism, Molecular Structure, Optics and Photonics, Retinaldehyde, Spectrophotometry},
	issn = {0006-3495},
	doi = {10.1016/S0006-3495(97)78342-5},
	author = {Volkov, V. V. and Svirko, Y P and Kamalov, Valey F. and Song, Li and El-Sayed, Mostafa A}
}
@article {1261,
	title = {Spectral diffusion within the porous silicon emission wavelength range on the nanosecond to millisecond time scale},
	journal = {J. Appl. Phys.Journal of Applied Physics},
	volume = {82},
	year = {1997},
	month = {1997},
	pages = {836},
	publisher = {AIP},
	abstract = {The emission spectrum from porous silicon (PS) at room temperature was recorded after different delay times ranging from 30 ns to 2.0 ms after pulsed laser excitation by using a gated charge-coupled device camera. In agreement with previous studies, the photoluminescence of porous silicon was found to redshift with delay time in the ns to 100 μs time scale. However, a study of the normalized band shape of the redshifted emission reveals that the emission spectrum retains its band shape rather than giving a distorted band shape that increases in intensity on the longer wavelength side. This behavior suggests that the redshift in the emission spectrum of porous silicon is a result of spectral diffusion resulting from energy transfer among emitters within the inhomogeneously broadened absorption spectrum. Furthermore, on the longer time scale (0.8{\textendash}2 ms), the much weaker, long wavelength emission spectrum is found to blueshift as the delay time is increased. Two peaks were resolved in the photoluminescence spectrum. One is centered around 650 nm and the other is centered around 750 nm. The photoluminescence at 600 and 800 nm have lifetimes of 0.35 and 0.19 ms, respectively. This observation suggests the existence of two distinct molecular species responsible for the observed photoluminescence in PS.},
	keywords = {elemental semiconductors, photoluminescence, porous materials, radiative lifetimes, red shift, silicon, spectral line breadth, spectral line shift, time resolved spectra},
	url = {http://dx.doi.org/10.1063/1.365781},
	author = {Song, Li},
	editor = {El-Sayed, Mostafa A and Chen, P.}
}
@article {865,
	title = {Studies of cation binding in ZnCl2-regenerated bacteriorhodopsin by x-ray absorption fine structures: effects of removing water molecules and adding Cl- ions.},
	journal = {Biophysical journal},
	volume = {73},
	year = {1997},
	month = {1997 Oct},
	pages = {2097-105},
	abstract = {The binding of Zn2+ in Zn2+-regenerated bacteriorhodopsin (bR) was studied under various conditions by x-ray absorption fine structures (XAFS). The 0.9:1 and 2:1 Zn2+:bR samples gave similar XAFS spectra, suggesting that Zn2+ might have only one strong binding site in bR. It was found that in aqueous bR solution, Zn2+ has an average of six oxygen or nitrogen ligands. Upon drying, two ligands are lost, suggesting the existence of two weakly bound water ligands near the cation-binding site in bacteriorhodopsin. When excess Cl- ions were present before drying in the Zn2+-regenerated bR samples, it was found that two of the ligands were replaced by Cl- ions in the dried film, whereas two remain unchanged. The above observations suggest that Zn2+ has three types of ligands in regenerated bR (referred to as types I, II, and III). Type I ligands are strongly bound. These ligands cannot be removed by drying or by exchanging with Cl- ions. Type II ligands cannot be removed by drying, but can be replaced by Cl- ligands. Type III ligands are weakly bound to the metal cation and are most likely water molecules that can be removed by evaporation under vacuum or by drying with anhydrous CaSO4. The results are discussed in terms of the possible structure of the strongly binding site of Zn2+ in bR.},
	keywords = {Bacteriorhodopsins, Binding Sites, Biophysical Phenomena, Biophysics, Cations, Chlorides, Kinetics, Ligands, Spectrum Analysis, Water, X-Rays, Zinc, Zinc Compounds},
	issn = {0006-3495},
	doi = {10.1016/S0006-3495(97)78240-7},
	author = {Zhang, K and Song, Li and Dong, J and El-Sayed, Mostafa A}
}
@article {1267,
	title = {Effect of Changing the Position and Orientation of Asp85 Relative to the Protonated Schiff Base within the Retinal Cavity on the Rate of Photoisomerization in Bacteriorhodopsin},
	journal = {The Journal of Physical Chemistry},
	volume = {100},
	year = {1996},
	note = {doi: 10.1021/jp960734r},
	month = {1996},
	pages = {10479 - 10481},
	publisher = {American Chemical Society},
	abstract = {Replacement of either Val49 with Ala or Ala53 with Val by site-specific mutagenesis is known to change the position and orientation of the protonated Schiff base relative to Asp85 within the retinal cavity of bacteriorhodopsin (bR) (Brown, L. S.; Gat, Y.; Sheves, M.; Yamazaki, Y.; Maeda, A.; Needleman, R.; Lanyi, J. K. Biochemistry 1994, 33, 12001). The effect of mutation on the rate of the subpicosecond photoisomerization of retinal in bR is examined by using a pump?probe technique. A decrease in the rate of photoisomerization of retinal in V49A and A53V is observed. This is discussed in terms of the previously proposed mechanism of the protein catalysis to the retinal photoisomerization process in bR.Replacement of either Val49 with Ala or Ala53 with Val by site-specific mutagenesis is known to change the position and orientation of the protonated Schiff base relative to Asp85 within the retinal cavity of bacteriorhodopsin (bR) (Brown, L. S.; Gat, Y.; Sheves, M.; Yamazaki, Y.; Maeda, A.; Needleman, R.; Lanyi, J. K. Biochemistry 1994, 33, 12001). The effect of mutation on the rate of the subpicosecond photoisomerization of retinal in bR is examined by using a pump?probe technique. A decrease in the rate of photoisomerization of retinal in V49A and A53V is observed. This is discussed in terms of the previously proposed mechanism of the protein catalysis to the retinal photoisomerization process in bR.},
	isbn = {0022-3654},
	doi = {doi: 10.1021/jp960734r},
	url = {http://dx.doi.org/10.1021/jp960734r},
	author = {Song, Li and El-Sayed, Mostafa A and Lanyi, Janos K.}
}
@article {869,
	title = {Excited-State Dynamics of a Protonated Retinal Schiff Base in Solution},
	journal = {The Journal of Physical Chemistry},
	volume = {100},
	year = {1996},
	note = {doi: 10.1021/jp962046d},
	month = {1996},
	pages = {18586 - 18591},
	publisher = {American Chemical Society},
	abstract = {The dynamics of all-trans and 13-cis retinal protonated Schiff base (RPSB) were studied in different solvents by means of picosecond transient spectroscopy. The decay time of the excited state absorption was found to be wavelength dependent due to the contribution of the faster decay of stimulated emission. The stimulated emission has a lifetime of a 2.5-4 ps while the excited state absorption decay is biexponential with lifetimes of 2.5-4 and 10-12 ps. The fluorescence quantum yield is strongly temperature dependent, but viscosity has a small effect on both excited-state lifetime and fluorescence quantum yield. This leads to the conclusion that there is a 600 cm-1 barrier in the excited-state which results from intramolecular electronic factors and not from the solvent viscosity. The comparison of these results with those for the retinal in rhodopsin and bacteriorhodopsin is discussed in terms of the protein catalysis for the retinal photoisomerization.},
	isbn = {0022-3654},
	url = {http://dx.doi.org/10.1021/jp962046d},
	author = {Logunov, Stephan L. and Song, Li and El-Sayed, Mostafa A}
}
@article {872,
	title = {Photoisomerization Quantum Yield and Apparent Energy Content of the K Intermediate in the Photocycles of Bacteriorhodopsin, Its Mutants D85N, R82Q, and D212N, and Deionized Blue Bacteriorhodopsin},
	journal = {The Journal of Physical Chemistry},
	volume = {100},
	year = {1996},
	note = {doi: 10.1021/jp9515242},
	month = {1996},
	pages = {2391 - 2398},
	publisher = {American Chemical Society},
	abstract = {The quantum yield of photoisomerization and the energy content of the K intermediate in the photocycle of bacteriorhodopsin and its mutants D85N, R82Q, and D212N and deionized blue bR were measured. Transient optical absorption and photoacoustic spectroscopy with excitation using 400 fs laser pulse were combined to obtain results. The spectroscopic characteristics of the excited state, the J and K intermediates in the photocycle of the mutants, and deionized blue bR were determined. The presence of both 13-cis and all-trans isomers in the ground state of light-adapted D85N, R82Q, and D212N and deionized blue bR makes extraction of the quantum yield for each isomer difficult. Thus, only average values of the quantum yield for these samples were determined. The replacement of charged groups in the vicinity of the retinal Schiff base was found to decrease the rate of the photoisomerization by up to 30 times, but with no signficant change in either the apparent quantum yield of the photoisomerization or the energy stored in the K intermediate. The results are discussed in terms of the different models for the excited and ground state potential surfaces of the retinal configuration in bacteriorhodopsin.The quantum yield of photoisomerization and the energy content of the K intermediate in the photocycle of bacteriorhodopsin and its mutants D85N, R82Q, and D212N and deionized blue bR were measured. Transient optical absorption and photoacoustic spectroscopy with excitation using 400 fs laser pulse were combined to obtain results. The spectroscopic characteristics of the excited state, the J and K intermediates in the photocycle of the mutants, and deionized blue bR were determined. The presence of both 13-cis and all-trans isomers in the ground state of light-adapted D85N, R82Q, and D212N and deionized blue bR makes extraction of the quantum yield for each isomer difficult. Thus, only average values of the quantum yield for these samples were determined. The replacement of charged groups in the vicinity of the retinal Schiff base was found to decrease the rate of the photoisomerization by up to 30 times, but with no signficant change in either the apparent quantum yield of the photoisomerization or the energy stored in the K intermediate. The results are discussed in terms of the different models for the excited and ground state potential surfaces of the retinal configuration in bacteriorhodopsin.},
	isbn = {0022-3654},
	url = {http://dx.doi.org/10.1021/jp9515242},
	author = {Logunov, Stephan L. and El-Sayed, Mostafa A and Song, Li and Lanyi, Janos K.}
}
@article {1286,
	title = {Enhancement of Metallic Silver Monomer Evaporation by the Adhesion of Polar Molecules to Silver Nanocluster Ions},
	journal = {The Journal of Physical Chemistry},
	volume = {99},
	year = {1995},
	note = {doi: 10.1021/j100019a061},
	month = {1995},
	pages = {7723 - 7730},
	publisher = {American Chemical Society},
	abstract = {View http://dx.doi.org/10.1021/j100019a061 for article{\textquoteright}s front page in lieu of an abstract},
	isbn = {0022-3654},
	doi = {doi: 10.1021/j100019a061},
	url = {http://dx.doi.org/10.1021/j100019a061},
	author = {Fagerquist, Clifton K. and Sensharma, Dilip K. and El-Sayed, Mostafa A and Rubio, Angel and Cohen, Marvin L.}
}
@article {1284,
	title = {Fourier-transform infrared spectroscopic comparison of cultured human fibroblast and fibrosarcoma cells},
	journal = {Proceedings of SPIE},
	volume = {2389},
	year = {1995},
	month = {1995},
	pages = {543},
	publisher = {SPIE},
	abstract = {Infrared vibration spectroscopy appears to be a more powerful technique for diagnosis than visible or UV spectroscopy. Advantages of IR spectra include: 1) vibrational motion has a smaller tissue absorption coefficient than electronic motion, 2) scattering of infrared radiation has a lower cross section than visible or UV light, (these two facts allow deeper penetration of IR radiation) and 3) vibration spectra provide a better fingerprint of chemical groups present in cells than the unresolved broad electronic spectrum of biological molecules. In the present work, Fourier-transform IR spectroscopy was used to compare cultured human fibroblast and malignant fibrosarcoma cells. Significant differences were observed by comparing the spectra of the normal cells with that of the cancer cells. the PO2 symmetric stretching mode at 1082cm-1 in the cancer cell is reduced in intensity. These observations are similar to those reported previously by Wong et al in comparing the IR spectra of pairs of normal and cancerous cells from the colon and cervix. However, the observed increase in the relative intensity of the symmetric to antisymmetric CH3 bending mode are only found in fibrosarcoma and basal cell carcinoma. The decrease in intensity of the CH2 bending mode relative to that of CH3 mode was observed only for fibrosarcoma cells. This finding with paired human fibroblast and fibrosarcoma cells suggests that fatty acid chains or side chains of protein in the cancer cells are partially degraded leading to more terminal carbon. It is also possible that changes in the environment upon carcinogenesis induces a change in the relative absorption cross sections for the CH3 and CH2 bending vibrations.
},
	doi = {10.1117/12.210030},
	url = {http://dx.doi.org/10.1117/12.210030},
	author = {Yang, Difei},
	editor = {Castro, D. and El Sayed, I.H. and El-Sayed, Mostafa A and Saxton, R. and Zhang, N.}
}
@article {1274,
	title = {A Fourier-transform infrared spectroscopic comparison of cultured human fibroblast and fibrosarcoma cells: a new method for detection of malignancies},
	journal = {Journal of clinical laser medicine \& surgery},
	volume = {13},
	year = {1995},
	pages = {55-59},
	abstract = {Infrared vibration spectroscopy appears to be a more powerful technique for tumor diagnosis than visible or UV spectroscopy. In the present work, Fourier-transform infrared (FTIR) spectroscopy was used to compare cultured normal fibroblast and fibrosarcoma cells. Significant differences were observed by comparing the spectra of the normal human cells with that of the cancer cells. The PO2 symmetric stretching mode at 1082 cm-1 is shifted to a higher frequency in the cancer cell and a broad band, whose center is located at 1064 cm-1 in the cancer cell is reduced in intensity. In addition, the decrease in intensity of the CH2 bending mode relative to that of CH3 mode is detectable only in the fibrosarcoma cell. This FTIR difference between fibroblast and fibrosarcoma cells suggests that either fatty acid chains or protein side chains of the cancer cells are partially degraded resulting in more terminal carbon (e.g., CH3). It is also possible that changes in the environment upon carcinogenesis induces a change in the relative absorption cross section for CH3 and CH2 bending vibrations. These results suggest that FTIR spectroscopy may become a promising and sensitive technique for tumor identification.},
	isbn = {1044-5471},
	author = {Yang, Difei and Castro, D. and El Sayed, I.H. and El-Sayed, Mostafa A and SAXTON, R.E. and ZHANG, N.Y.I.}
}
@article {1283,
	title = {On the molecular mechanisms of the rapid and slow solar-to-electric energy storage processes by the other natural photosynthetic system, bacteriorhodopsin},
	journal = {Pure and applied chemistry},
	volume = {67},
	year = {1995},
	pages = {149-149},
	publisher = {BLACKWELL SCIENTIFIC PUBLICATIONS},
	abstract = {Upon the absorption of solar energy by retinal in bacterioi..>dopsin highly specific photoisomerization of the retinal around the C13 -C14 bond takes place. This is followed by the formation of a number of intermediates resulting from conformational changes of the protein around the retinal which leads to the deprotonation of the protonated Schiff base of the retinylidene system. Thisis the switch of the proton pump which leads to the last step in the storage of solar energy in the form of electric energy by this photosynthetic system. The removal of metal cations from bR is found to inhibit the deprotonation process.
In the present paper we summarize the results of our studies and the others regarding two important questions in the conversion process: 1) what is(are) the molecular mechanism(s) of the protein catalysis of the photoisomerizationprocess and 2) what is the role of metal cations in the deprotonation process of the protonated Schiff base (the switch of the proton pump)? In order to answer the first question, the results of the subpicosecondphotoisomerization rate of retinal in bR and in a number of its relevant mutants are discussed in terms of the steric and electronic factors. In an effort to answer the second question,we discussed the results of the binding studies of Ca*+to bR, to its mutants and to bR after its C- terminus is cleaved. From these results and the results of Roux et al. on the 31P NMR of Nd3+ regenerated bR, we concluded that one or two metal cations strongly bound to the protein but not on the surface, are functionally important. The model in which these metal cation@)control the pK values of Aspartic acids in the 85 and 212 positions and that of the protonated Schiff base (PSB) during the photocycle is discussed.},
	isbn = {0033-4545},
	author = {El-Sayed, Mostafa A and Griffiths, Jennifer A. and Song, Li and Zhang, N.}
}
@article {1268,
	title = {Retinal Isomer Composition in Some Bacteriorhodopsin Mutants under Light and Dark Adaptation Conditions},
	journal = {The Journal of Physical Chemistry},
	volume = {99},
	year = {1995},
	note = {doi: 10.1021/j100024a056},
	month = {1995},
	pages = {10052 - 10055},
	publisher = {American Chemical Society},
	abstract = {View http://dx.doi.org/10.1021/j100024a056 for the article{\textquoteright}s first page in lieu of an abstract},
	isbn = {0022-3654},
	doi = {doi: 10.1021/j100024a056},
	url = {http://dx.doi.org/10.1021/j100024a056},
	author = {Song, Li and Yang, Difei and El-Sayed, Mostafa A and Lanyi, Janos K.}
}
@article {1277,
	title = {pH Dependence of the Rate and Quantum Yield of the Retinal Photoisomerization in Bacteriorhodopsin},
	journal = {The Journal of Physical Chemistry},
	volume = {98},
	year = {1994},
	note = {doi: 10.1021/j100093a003},
	month = {1994},
	pages = {10674 - 10677},
	publisher = {American Chemical Society},
	abstract = {View http://dx.doi.org/10.1021/j100093a003 for article{\textquoteright}s front page in lieu of an abstract},
	isbn = {0022-3654},
	doi = {doi: 10.1021/j100093a003},
	url = {http://dx.doi.org/10.1021/j100093a003},
	author = {Logunov, Stephan L. and Song, Li and El-Sayed, Mostafa A}
}
@article {859,
	title = {The pH dependence of the subpicosecond retinal photoisomerization process in bacteriorhodopsin: evidence for parallel photocycles.},
	journal = {Biophysical journal},
	volume = {67},
	year = {1994},
	month = {1994 Nov},
	pages = {2008-12},
	abstract = {The pH dependence of the subpicosecond decay of the retinal photoexcited state in bacteriorhodopsin (bR) is determined in the pH range 6.8-11.3. A rapid change in the decay rate of the retinal photoexcited state is observed in the pH range 9-10, the same pH range in which a rapid change in the M412 formation kinetics was observed. This observation supports the previously proposed heterogeneity model in which parallel photocycles contribute to the observed pH dependence of the M412 formation kinetics in bR.},
	keywords = {Bacteriorhodopsins, Biophysical Phenomena, Biophysics, Hydrogen-Ion Concentration, Isomerism, Kinetics, Molecular Structure, Photochemistry, Retinaldehyde},
	issn = {0006-3495},
	doi = {10.1016/S0006-3495(94)80684-8},
	author = {Song, Li and Logunov, Stephan L. and Yang, Difei and El-Sayed, Mostafa A}
}
