@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 {1656,
	title = {Enhanced Electrochemical Dark-Field Scattering Modulation on Single Hybrid Core-Shell Nanostructure},
	journal = {The Journal of Physical Chemistry C},
	year = {2019},
	author = {Zhou, J. and Panikkanvalappil, S.R. and Kang, S. and Yu, S. and Zhang, S. and El-Sayed, M.A. and Tsukruk, V.V.}
}
@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 {1640,
	title = {Electrochemical Synthesis of Ammonia from N2 and H2O under Ambient Conditions Using Pore-Size-Controlled Hollow Gold Nanocatalysts with Tunable Plasmonic Properties},
	journal = {The journal of physical chemistry letters},
	year = {2018},
	author = {M. Nazemi and El-Sayed, M. A.}
}
@article {1637,
	title = {Enhancing the rate of electrochemical nitrogen reduction reaction for ammonia synthesis under ambient conditions using hollow gold nanocages},
	journal = {Nano Energy},
	year = {2018},
	keywords = {display},
	author = {M. Nazemi and Panikkanvalappil, S. R. and El-Sayed, M. A.}
}
@article {1597,
	title = {Efficacy, long-term toxicity, and mechanistic studies of gold nanorods photothermal therapy of cancer in xenograft mice},
	journal = {Proceedings of the National Academy of Sciences},
	year = {2017},
	keywords = {display},
	author = {Ali, Moustafa RK and et al.}
}
@article {1613,
	title = {Electrochromic tuning of transparent gold nanorods with poly [(3, 4-propylenedioxy) pyrrole] shells in the near-infrared region},
	journal = {Journal of Materials Chemistry C},
	year = {2017},
	author = {Zhou, J and et al.}
}
@article {1628,
	title = {The effect of plasmon resonance coupling in P3HT-coated silver nanodisk monolayers on their optical sensitivity},
	journal = {Journal of Materials Chemistry C},
	year = {2016},
	author = {Geldmeier, J. A. and et al.}
}
@article {1624,
	title = {Effects of the substrate refractive index, the exciting light propagation direction, and the relative cube orientation on the plasmonic coupling behavior of two silver nanocubes at different separations},
	journal = {Journal of Physical Chemistry C},
	year = {2016},
	author = {Hooshmand, N. and et al.}
}
@article {1615,
	title = {Efficacy and toxicity of plasmonic photothermal therapy (PPTT) using gold nanorods (GNRs) against mammary tumors in dogs and cats},
	journal = {Nanomedicine: Nanotechnology, Biology and Medicine},
	year = {2016},
	author = {Abdoon, A S and et al.}
}
@article {1593,
	title = { Electrically Controlled Plasmonic Behavior of Gold Nanocube@ Polyaniline Nanostructures: Transparent Plasmonic Aggregates},
	journal = {Chem. Mater.},
	year = {2016},
	author = {Jeon, J.-W. and Ledin, P. A. and Geldmeier, J. A. and Ponder, J. F. and Mahmoud, M A and El-Sayed, M. and Reynolds, J. R. and Tsukruk, V. V.}
}
@article {1590,
	title = {Elucidation of Ultraviolet RadiationInduced Cell Responses and Intracellular Biomolecular Dynamics in Mammalian Cells Using Surface-Enhanced Raman Spectroscopy},
	journal = {Chemical Science },
	year = {2016},
	author = {Panikkanvalappil, S. R. and Hira, S. M. and El-Sayed, M. A.}
}
@article {1623,
	title = {Enhanced Electrocatalytic Activity toward the Oxygen Reduction Reaction through Alloy Formation: Platinum{\textendash}Silver Alloy Nanocages},
	journal = {Journal of Physical Chemistry C},
	year = {2016},
	author = {Bordley, JA and et al.}
}
@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 {1363,
	title = {Electrically Tunable Plasmonic Behavior of Nanocube-Polymer Nanomaterials Induced by a Redox Active Electrochromic Polymer},
	journal = {ACS nano},
	year = {2014},
	isbn = {1936-0851},
	author = {K{\"o}nig, Tobias AF and Ledin, Petr A and Kerszulis, Justin and Mahmoud, Mahmoud A. and El-Sayed, Mostafa A. and Reynolds, John R and Tsukruk, Vladimir V.}
}
@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 {1370,
	title = {Enhancing the Efficiency of Gold Nanoparticles Treatment of Cancer by Increasing Their Rate of Endocytosis and Cell Accumulation Using Rifampicin},
	journal = {Journal of the American Chemical Society},
	volume = {136},
	number = {12},
	year = {2014},
	pages = {4464-4467},
	isbn = {0002-7863},
	author = {Ali, Moustafa RK and Panikkanvalappil, Sajanlal R. and El-Sayed, Mostafa A.}
}
@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 {1350,
	title = {Enhancing Colloidal Metallic Nanocatalysis: Sharp Edges and Corners for Solid Nanoparticles and Cage Effect for Hollow Ones},
	journal = {Acc Chem Res},
	year = {2013},
	note = {MEDLINE AN 2013361444(Journal; Article; (JOURNAL ARTICLE))},
	month = {//},
	abstract = {There are two main classes of metallic nanoparticles: solid and hollow. Each type can be synthesized in different shapes and structures. Practical use of these nanoparticles depends on the properties they acquire on the nanoscale. Plasmonic nanoparticles of silver and gold are the most studied, with applications in the fields of sensing, medicine, photonics, and catalysis. In this Account, we review our group{\textquoteright}s work to understand the catalytic properties of metallic nanoparticles of different shapes. Our group was the first to synthesize colloidal metallic nanoparticles of different shapes and compare their catalytic activity in solution. We found that the most active among these were metallic nanoparticles having sharp edges, sharp corners, or rough surfaces. Thus, tetrahedral platinum nanoparticles are more active than spheres. We proposed this happens because sharper, rougher particles have more valency-unsatisfied surface atoms (i.e., atoms that do not have the complete number of bonds that they can chemically accommodate) to act as active sites than smoother nanoparticles. We have not yet resolved whether these catalytically active atoms act as catalytic centers on the surface of the nanoparticle (i.e., heterogeneous catalysis) or are dissolved by the solvent and perform the catalysis in solution (i.e., homogenous catalysis). The answer is probably that it depends on the system studied. In the past few years, the galvanic replacement technique has allowed synthesis of hollow metallic nanoparticles, often called nanocages, including some with nested shells. Nanocage catalysts show strong catalytic activity. We describe several catalytic experiments that suggest the reactions occurred within the cage of the hollow nanocatalysts: (1) We synthesized two types of hollow nanocages with double shells, one with platinum around palladium and the other with palladium around platinum, and two single-shelled nanocages, one made of pure platinum and the other made of pure palladium. The kinetic parameters of each double-shelled catalyst were comparable to those of the single-shelled nanocage of the same metal as the inside shell, which suggests the reactions are taking place inside the cavity. (2) In the second set of experiments, we used double-shelled, hollow nanoparticles with a plasmonic outer gold surface and a non-plasmonic inner catalytic layer of platinum as catalysts. As the reaction proceeded and the dielectric function of the interior gold cavity changed, the plasmonic band of the interior gold shell shifted. This strongly suggested that the reaction had taken place in the nanocage. (3) Finally, we placed a catalyst on the inside walls of hollow nanocages and monitored the corresponding reaction over time. The reaction rate depended on the size and number of holes in the walls of the nanoparticles, strongly suggesting the confinement effect of a nanoreactor.[on SciFinder (R)]},
	isbn = {1520-4898},
	author = {Mahmoud, Mahmoud A. and Narayanan, Radha and El-Sayed, Mostafa A.}
}
@article {1395,
	title = {Exploiting the Nanoparticle Plasmon Effect: Observing Drug Delivery Dynamics in Single Cells via Raman/Fluorescence Imaging Spectroscopy},
	journal = {Acs Nano},
	volume = {7},
	number = {8},
	year = {2013},
	note = {Kang, Bin Afifi, Marwa M. Austin, Lauren A. El-Sayed, Mostafa A.},
	month = {Aug},
	pages = {7420-7427},
	isbn = {1936-0851},
	doi = {10.1021/nn403351z},
	author = {Kang, B. and Afifi, M. M. and Austin, Lauren and El-Sayed, M. A.}
}
@article {1335,
	title = {Effect of the Dielectric Constant of the Surrounding Medium and the Substrate on the Surface Plasmon Resonance Spectrum and Sensitivity Factors of Highly Symmetric Systems: Silver Nanocubes},
	journal = {Journal of the American Chemical Society},
	volume = {134},
	number = {14},
	year = {2012},
	note = {Times Cited: 3Mahmoud, Mahmoud A. Chamanzar, Maysamreza Adibi, Ali El-Sayed, Mostafa A.},
	month = {Apr},
	pages = {6434-6442},
	abstract = {Silver nanocubes (AgNCs), 60 nm, have four extinction surface plasmon resonance (SPR) peaks. The finite difference time domain (FDTD) simulation method is used to assign the absorption and scattering peaks and also to calculate the plasmon field intensity for AgNCs. Because AgNCs have a highly symmetric cubic shape, there is a uniform distribution of the plasmon field around them, and they are thus sensitive to asymmetric dielectric perturbations. When the dielectric medium around a nanoparticle is changed anisotropically, either by placing the particle on a substrate or by coating it asymmetrically with a solvent, the plasmon field is distorted, and the plasmonic absorption and scattering spectra could shift differently. For the 60 nm AgNC, we found that the scattering resonance peak shifted more than the absorption peak. This changes the extinction bandwidth of these overlapping absorption and scattering bands, and consequently the figure of merit of the nanoparticle, as a localized SPR sensor, no longer has a constant value.},
	isbn = {0002-7863},
	doi = {10.1021/ja300901e},
	author = {Mahmoud, M A and Chamanzar, M. and Adibi, A. and El-Sayed, M. A.}
}
@article {1341,
	title = {Extinction vs Absorption: Which Is the Indicator of Plasmonic Field Strength for Silver Nanocubes?},
	journal = {Journal of Physical Chemistry C},
	volume = {116},
	number = {43},
	year = {2012},
	note = {Times Cited: 0Near, Rachel Hayden, Steven El-Sayed, Mostafa},
	month = {Nov},
	pages = {23019-23026},
	abstract = {This investigation demonstrates the contributions of absorption and scattering to the extinction spectrum of silver nanocubes with multipole resonances and the complexity of the resulting plasmon field strengths for these varying modes. The three-dimensional plasmonic field distribution and orientation around a silver nanosphere (AgNS; 40 nm) and a silver nanocube (AgNC; 40, 60, 86 nm) were calculated in the visible via the discrete dipole approximation. The three-dimensional nature of these particles allows for significant contribution from the quadrupole mode in some cases. The AgNS displays one plasmon band, its dipole mode, and has little contribution from scattering. The maximum plasmon field occurs at the extinction maximum, as expected. The 40 nm AgNC exhibits multiple plasmon bands, and the highest maximum field strength is attained from excitation of the quadrupole mode, not the dipole mode. As the size of the AgNC increases, the contribution from scattering increases. When the contribution from scattering is greater than the contribution from absorption in a AgNC, the field strength within a plasmon mode trends with the absorption and not with the extinction or cattering. This should be considered in applications of AgNCs, as excitation of the largest peak in the experimental extinction spectrum will not always result in the strongest plasmon field strength.},
	isbn = {1932-7447},
	doi = {10.1021/jp309272b},
	author = {Near, R. and Hayden, S. and El-Sayed, M.}
}
@article {1081,
	title = {Electrochemical Fabrication of Strontium-Doped TiO(2) Nanotube Array Electrodes and Investigation of Their Photoelectrochemical Properties},
	journal = {Journal of Physical Chemistry C},
	volume = {115},
	number = {27},
	year = {2011},
	note = {Hamedani, Hoda A. Allam, Nageh K. Garmestani, Hamid El-Sayed, Mostafa A.},
	month = {Jul},
	pages = {13480-13486},
	abstract = {In recent years, considerable efforts have been made to improve the performance of photoactive nanostructured materials for water-splitting applications. Herein, we report on the fabrication and photoelectrochemical properties of highly ordered Sr-doped TiO(2) nanotube arrays synthesized via a one-step electrochemical anodization technique. Nanotube arrays of Sr-doped TiO(2) were synthesized via anodization of titanium foil in aqueous electrolytes containing NH(4)F and various concentrations of Sr(OH)(2) at different electrolyte pHs. The morphology and quality of the fabricated materials were found to be significantly affected by the pH of the electrolyte as well as the solubility limit of Sr(OH)(2) in the test electrolyte. The photoelectrochemical measurements revealed that Sr doping can significantly improve the photoconversion efficiency of the material. Using Sr-doped TiO(2) nanotube arrays, an electrode photoconversion efficiency of 0.69\% was obtained, which is more than 3 times higher than that of the undoped nanotube arrays (0.2\%) fabricated and tested under the same conditions.},
	isbn = {1932-7447},
	doi = {10.1021/jp201194b},
	author = {Hamedani, H. A. and Allam, N. K. and Garmestani, H. and El-Sayed, Mostafa A}
}
@article {1106,
	title = {Enhanced Photoassisted Water Electrolysis Using Vertically Oriented Anodically Fabricated Ti-Nb-Zr-O Mixed Oxide Nanotube Arrays},
	journal = {Acs Nano},
	volume = {4},
	number = {10},
	year = {2010},
	note = {Allam, Nageh K. Alamgir, Faisal El-Sayed, Mostafa A.},
	month = {Oct},
	pages = {5819-5826},
	abstract = {Self-ordered, highly oriented arrays of titanium-niobium-zirconium mixed oxide nanotube films were fabricated by the anodization of Ti(35)Nb(5)Zr alloy in aqueous and formamide electrolytes containing NH(4)F at room temperature. The nanostructure topology was found to depend on the nature of the electrolyte and the applied voltage. Our results demonstrate the possibility to grow mixed oxide nanotube array films possessing several-micrometer-thick layers by a simple and straightforward electrochemical route. The fabricated Ti-Nb-Zr-O nanotubes showed a similar to 17.5\% increase in the photoelectrochemical water oxidation efficiency as compared to that measured for pure TiO(2) nanotubes under UV illumination (100 mW/cm(2), 320-400 nm, 1 M KOH). This enhancement could be related to a combination of the effect of the thin wall of the fabricated Ti-Nb-Zr-O nanotubes (10 +/- 2 nm) and the formation of Zr oxide and Nb oxide layers on the nanotube surface, which seems to slow down the electron-hole recombination in a way similar to that reported for Gratzel solar cells.},
	isbn = {1936-0851},
	doi = {10.1021/nn101678n},
	author = {Allam, N. K. and Alamgir, F. 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 {1111,
	title = {Effect of Orientation on Plasmonic Coupling between Gold Nanorods},
	journal = {Acs Nano},
	volume = {3},
	number = {11},
	year = {2009},
	note = {Tabor, Christopher Van Haute, Desiree El-Sayed, Mostafa A.},
	month = {Nov},
	pages = {3670-3678},
	abstract = {Radiative coupling of induced plasmonic fields in metal nanoparticles has drawn increasing attention in the recent literature due to a combination of improved experimental methods to study such phenomena and numerous potential applications, such as plasmonic nanoparticle rulers and plasmonic circuitry. Many groups, including ours, have used a near-exponential fit to express the size scaling of plasmonic coupling. First, we show experimental agreement between previously simulated nanorod coupling and plasmonic coupling in electron beam lithography (EBL) fabricated nanorods using the near-exponential expression. Next, we study the effect of nanoparticle orientation on plasmonic coupling using EBL and DDA simulations. We develop a mathematical relationship that is consistent with our findings and quantitatively describes plasmonic coupling between nanorods as a function of orientation, separation, induced dipole strength, and the dielectric constant of the medium. For applications utilizing plasmonic coupling to become viable with particle shapes that do not have spherical symmetry, such as nanoprisms and nanorods, comparison of the experimental and theoretical results of how particle orientation affects plasmonic coupling is essential.},
	isbn = {1936-0851},
	doi = {10.1021/nn900779f},
	author = {Tabor, C. E. and Van Haute, D. and El-Sayed, Mostafa A}
}
@article {1113,
	title = {Exciton Lifetime Tuning by Changing the Plasmon Field Orientation with Respect to the Exciton Transition Moment Direction: CdTe-Au Core-Shell Nanorods},
	journal = {Nano Letters},
	volume = {9},
	number = {3},
	year = {2009},
	note = {Neretina, Svetlana Qian, Wei Dreaden, Erik C. El-Sayed, Mostafa A. Hughes, Robert A. Preston, John S. Mascher, Peter},
	month = {Mar},
	pages = {1242-1248},
	abstract = {We studied the anisotropy of the influence of plasmonic fields, arising from the optical excitation of a gold nanoshell plasmon absorption at 770 nm, on the lifetime of the bandgap state of the CdTe core in vertically aligned CdTe-Au core-shell nanorods. The previously observed decrease in the lifetime was studied as a function of the tilt angle between the long axis of the nanorod and the electric field polarization direction of the plasmon inducing exciting light. It is observed that the strongest enhancement to the exciton relaxation rate occurs when the two axes are parallel to one another. These results are discussed in terms of the coupling between the exciton transition moment of the CdTe rod and the electric field polarization direction of the gold nanoshell plasmon at 770 nm, which was determined from theoretical modeling based on the discrete dipole approximation.},
	isbn = {1530-6984},
	doi = {10.1021/nl900183m},
	author = {Neretina, Svetlana and Qian, Wei and Dreaden, Erik and El-Sayed, Mostafa A and Hughes, Robert A and Preston, John S and Mascher, Peter}
}
@article {1143,
	title = {The effect of plasmon field on the coherent lattice phonon oscillation in electron-beam fabricated gold nanoparticle pairs},
	journal = {Nano Letters},
	volume = {7},
	number = {10},
	year = {2007},
	note = {Huang, Wenyu Qian, Wei Jain, Prashant K. El-Sayed, Mostafa A.},
	month = {Oct},
	pages = {3227-3234},
	abstract = {By using electron beam lithography, we fabricated pairs of gold nanoparticles with varying interparticle separation. Double-beam femtosecond transient absorption spectroscopy was used to determine the coherent lattice oscillation frequency as a function of the interparticle separation in the presence of the plasmon field excited by the monitoring probe light. We found that the fractional shift in the coherent lattice phonon oscillation frequency follows an exponential decay with respect to the interparticle gap scaled by the disc diameter with the same decay constant as that previously observed for the fractional shift in the surface plasmon electronic oscillation resonance frequency. This strongly suggests that it is the near-field coupling between the particles that shifts both the coherent electronic oscillation (plasmon) frequency and the coherent lattice oscillation (phonon) frequency. The similar trend in the effect of interparticle coupling on the plasmon frequency and the phonon frequency is essentially a reflection of the universal scaling behavior of the distance decay of the interparticle plasmonic near-field. It is shown that the observed decrease in the lattice oscillation frequency with decrease in the interparticle distance is the result of a reduction in the effective free electron density within each nanoparticle pair partner as a result of the polarizing perturbation of the plasmonic field of the other nanoparticle in the pair.},
	isbn = {1530-6984},
	doi = {10.1021/nl071813p},
	author = {Huang, Wenyu and Qian, Wei and Jain, Prashant K and El-Sayed, Mostafa A}
}
@article {1145,
	title = {Effect of plasmonic gold nanoparticles on benign and malignant cellular autofluorescence: A novel probe for fluorescence based detection of cancer},
	journal = {Technology in Cancer Research \& Treatment},
	volume = {6},
	number = {5},
	year = {2007},
	note = {El-Sayed, Ivan Huang, Xiaohua Macheret, Fima Humstoe, Joseph Oren Kramer, Randall El-Sayed, Mostafa},
	month = {Oct},
	pages = {403-412},
	abstract = {Due to the strong surface fields of noble metal nanoparticles, absorption and scattering of electromagnetic radiation is greatly enhanced. Noble metallic nanoparticles represent potential novel optical probes for simultaneous molecular imaging and photothermal cancer therapy using the enhanced scattering and absorption of light. Further, gold nanoparticles can affect molecular fluorescence via chemical, electronic, or photonic interactions. Live cells generate fluorescence due to intracellular and extracellular molecules. Differences in the biochemical composition between healthy and malignant cells can be exploited in vivo to help identify cancer spectroscopically. The interaction of gold nanoparticles with cellular autofluorescence has not yet been characterized. We hypothesized that gold nanoparticles delivered to live cells in vitro would alter cellular autofluorescence and may be useful as a novel class of contrast agent for fluorescence based detection of cancer. The fluorescence of two fluorophores that are responsible for tissue autofluorescence, NADH and collagen, and of two oral squamous carcinoma cell lines and one immortalized benign epithelial cell line were measured in vitro. Gold nanoparticles of different shapes, both spheres and rods, quenched the fluorescence of the soluble NADH and collagen. Reduction of NADH fluorescence was due to oxidation of NADH to NAD+ catalyzed by gold nanoparticles (results we previously published). Reduction of collagen fluorescence appears due to photonic absorption of light. Furthermore, a mean quenching of 12/8\% (p < 0.00050) of the tissue autofluorescence of cell suspensions was achieved in this model when nanospheres were incubated with the live cells. Gold nanospheres significantly decrease cellular autofluorescence of live cells under physiological conditions when excited at 280nm. This is the first report to our knowledge to suggest the potential of developing targeted gold nanoparticles optical probes as contrast agents for fluorescence based diagnoses of cancer.},
	isbn = {1533-0346},
	author = {El Sayed, I.H. and Huang, Xiaohua and Macheret, F. and Humstoe, J. O. and Kramer, R. and El-Sayed, Mostafa A}
}
@article {1144,
	title = {Effect of the lattice crystallinity on the electron-phonon relaxation rates in gold nanoparticles},
	journal = {Journal of Physical Chemistry C},
	volume = {111},
	number = {29},
	year = {2007},
	note = {Huang, Wenyu Qian, Wei El-Sayed, Mostafa A. Ding, Yong Wang, Zhong Lin},
	month = {Jul},
	pages = {10751-10757},
	abstract = {In order to study the importance of surface phonons on the electron-phonon relaxation in plasmonic nanoparticles, the effect of size, shape, and materials have recently been studied. Gold and silver nanoparticles have shown no dependence on size and shape while copper nanoparticles have shown some size dependence. This suggests that the bulk phonons, which are sensitive to the bulk-phase structure, are solely responsible for the relaxation of the hot electron in gold and silver plasmonic nanoparticles. The importance of bulk phonons should depend on the degree of crystallinity. In the present study, we have found that the electron-phonon relaxation rate decreases greatly when polycrystalline prismatic gold nanoparticles are annealed and transformed into nearly single-crystalline nanospheres. The results are explained by the presence of high-density grain boundaries with dense, high-frequency molecular type vibrations which are effective in removing the energy of the excited electrons in the polycrystalline prismatic nanoparticles.},
	isbn = {1932-7447},
	doi = {10.1021/jp0738917},
	author = {Huang, Wenyu and Qian, Wei and El-Sayed, Mostafa A and Ding, Y. and Wang, Z.L.}
}
@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 {1167,
	title = {Effect of colloidal nanocatalysis on the metallic nanoparticle shape: The Suzuki reaction},
	journal = {Langmuir},
	volume = {21},
	number = {5},
	year = {2005},
	note = {Narayanan, R El-Sayed, MA},
	month = {Mar},
	pages = {2027-2033},
	abstract = {Dominantly tetrahedral shaped poly(vinylpyrrolidone) -platinum (PVP-Pt) nanoparticles are shown to catalyze the Suzuki reaction between phenylboronic acid and iodobenzene but are not as active as the spherical palladium nanoparticles studied previously. The dominantly tetrahedral PVP-Pt nanoparticles (55 +/- 4\% regular tetrahedral, 22 +/- 2\% distorted tetrahedral, and 23 +/- 2\% spherical nanoparticles) are synthesized by using the hydrogen reduction method. The transmission electron microscopy (TEM) results show that a transformation of shape from tetrahedral to spherical Pt nanoparticles takes place 3 h into the first cycle of the reaction. After the first cycle, the spherical nanoparticles have a similar size distribution to that of the tetrahedral nanoparticles before the reaction and the observed shape distribution is 18 +/- 6\% regular tetrahedral, 28 +/- 5\% distorted tetrahedral, and 54 +/- 5\% spherical nanoparticles. After the second cycle of the Suzuki reaction, the shape distribution is 13 +/- 5\% regular tetrahedral, 24 +/- 5\% distorted tetrahedral, and 63 +/- 7\% spherical nanoparticles. After the second cycle, the transformed spherical nanoparticles continue to grow, and this could be due to the strong capping action of the higher molecular weight PVP (M-w = 360 000), which makes the nanoparticles more resistant to aggregation and precipitation, unlike the Pd nanoparticles capped with the lower molecular weight PVP (M-w = 40 000) used previously. The transformation in shape also occurs when the nanoparticles are refluxed in the presence of the solvent, sodium acetate, and iodobenzene and results in spherical nanoparticles with a similar size distribution to that of the tetrahedral nanoparticles before any perturbations. However, in the presence of phenylboronic acid, the regular tetrahedral nanoparticles remain dominant (51 6\%) and maintain their size. These results support our previous studies in which we proposed that phenylboronic acid binds to the nanoparticle surface and thus acts as a capping agent for the particle and reacts with the iodobenzene. Recycling the nanoparticles results in a drastic reduction of the catalytic activity, and this must be due to the transformation of shape from the dominantly tetrahedral to the larger dominantly spherical nanoparticles. This also supports results in the literature that show that spherical platinum nanoparticles do not catalyze this reaction.},
	isbn = {0743-7463},
	doi = {10.1021/la047600m},
	author = {Narayanan, Radha and El-Sayed, Mostafa A}
}
@article {819,
	title = {Effect of Colloidal Catalysis on the Nanoparticle Size Distribution:  Dendrimer-Pd vs PVP-Pd Nanoparticles Catalyzing the Suzuki Coupling Reaction},
	journal = {The Journal of Physical Chemistry B},
	volume = {108},
	year = {2004},
	note = {doi: 10.1021/jp037169u},
	month = {2004},
	pages = {8572 - 8580},
	publisher = {American Chemical Society},
	abstract = {A comparison of the stability and catalytic activity of PAMAM?OH generation 4 dendrimer?Pd nanoparticles (1.3 {\textpm} 0.1 nm) with the previously studied PVP?Pd nanoparticles (2.1 {\textpm} 0.1 nm) in the Suzuki coupling reaction between phenylboronic acid and iodobenzene is conducted. After the first cycle, the average size of the PVP?Pd nanoparticles increases by 38\% and the dendrimer?Pd nanoparticles increases by 54\%. After the second cycle, the PVP?Pd nanoparticles decrease in size by 24\% whereas the dendrimer?Pd nanoparticles continue to increase in size by 35\%. The strong encapsulating action of the PAMAM?OH generation 4 dendrimer?Pd nanoparticles could make the rate of conversion to the full nanoparticle size slow, resulting in a large excess Pd metal atom concentration in solution, resulting in the continuous growth of the nanoparticles during the catalytic reaction. The effect of the individual reactants on the stability of the dendrimer?Pd nanoparticles has also been investigated and found to be similar to that observed for the PVP?Pd nanoparticles previously. It was found that the nanoparticle size growth occurs while refluxing in the presence of only the solvent, sodium acetate, or iodobenzene. However, the presence of phenylboronic acid is found to inhibit the particle growth, suggesting that it acts as a capping agent. Thus, the reaction mechanism must involve the adsorption of phenylboronic acid to the nanoparticle surface, which subsequently reacts with the iodobenzene in solution. This is similar to the mechanism found previously on PVP?Pd nanoparticles, suggesting that the mechanism is insensitive to the capping material used. The ratio of the yield of biphenyl formed in the second cycle to that in the first cycle is higher for the dendrimer?Pd nanoparticles catalyzed reaction than for the PVP?Pd nanoparticles. This could be due to the greater stability of the dendrimer?Pd nanoparticles and the increase in its size during the reaction. The larger PVP?Pd nanoparticles studied previously is believed to aggregate and precipitate out of solution during the second cycle. The presence of excess dendrimer is found to severely diminish the catalytic activity of the dendrimer?Pd nanoparticles and also diminishes the change in the Pd nanoparticle size during the catalysis.A comparison of the stability and catalytic activity of PAMAM?OH generation 4 dendrimer?Pd nanoparticles (1.3 {\textpm} 0.1 nm) with the previously studied PVP?Pd nanoparticles (2.1 {\textpm} 0.1 nm) in the Suzuki coupling reaction between phenylboronic acid and iodobenzene is conducted. After the first cycle, the average size of the PVP?Pd nanoparticles increases by 38\% and the dendrimer?Pd nanoparticles increases by 54\%. After the second cycle, the PVP?Pd nanoparticles decrease in size by 24\% whereas the dendrimer?Pd nanoparticles continue to increase in size by 35\%. The strong encapsulating action of the PAMAM?OH generation 4 dendrimer?Pd nanoparticles could make the rate of conversion to the full nanoparticle size slow, resulting in a large excess Pd metal atom concentration in solution, resulting in the continuous growth of the nanoparticles during the catalytic reaction. The effect of the individual reactants on the stability of the dendrimer?Pd nanoparticles has also been investigated and found to be similar to that observed for the PVP?Pd nanoparticles previously. It was found that the nanoparticle size growth occurs while refluxing in the presence of only the solvent, sodium acetate, or iodobenzene. However, the presence of phenylboronic acid is found to inhibit the particle growth, suggesting that it acts as a capping agent. Thus, the reaction mechanism must involve the adsorption of phenylboronic acid to the nanoparticle surface, which subsequently reacts with the iodobenzene in solution. This is similar to the mechanism found previously on PVP?Pd nanoparticles, suggesting that the mechanism is insensitive to the capping material used. The ratio of the yield of biphenyl formed in the second cycle to that in the first cycle is higher for the dendrimer?Pd nanoparticles catalyzed reaction than for the PVP?Pd nanoparticles. This could be due to the greater stability of the dendrimer?Pd nanoparticles and the increase in its size during the reaction. The larger PVP?Pd nanoparticles studied previously is believed to aggregate and precipitate out of solution during the second cycle. The presence of excess dendrimer is found to severely diminish the catalytic activity of the dendrimer?Pd nanoparticles and also diminishes the change in the Pd nanoparticle size during the catalysis.},
	isbn = {1520-6106},
	doi = {10.1021/jp037169u},
	url = {http://dx.doi.org/10.1021/jp037169u},
	author = {Narayanan, Radha and El-Sayed, Mostafa A}
}
@article {1177,
	title = {Effect of nanocatalysis in colloidal solution on the tetrahedral and cubic nanoparticle SHAPE: Electron-transfer reaction catalyzed by platinum nanoparticles},
	journal = {Journal of Physical Chemistry B},
	volume = {108},
	number = {18},
	year = {2004},
	note = {Narayanan, R El-Sayed, MA},
	month = {May},
	pages = {5726-5733},
	abstract = {The stability of tetrahedral and cubic platinum nanoparticles during the catalysis of the electron-transfer reaction between hexacyanoferrate (III) and thiosulfate ions in colloidal solution at room temperature was studied by using TEM and HRTEM. Before the reaction, the dominantly tetrahedral nanoparticles have a shape distribution of 55 +/- 4\% regular tetrahedral, 22 +/- 2\% distorted tetrahedral, and 23 +/- 2\% spherical nanoparticles, and the dominantly cubic nanoparticles have an initial shape distribution of 56 4\% regular cubes, 13 +/- 1\% distorted cubes, and 31 +/- 3\% truncated octahedral nanoparticles. The amount of tetrahedral nanoparticles decreases by 60 +/- 5\% after the first cycle and by 62 +/- 4\% after the second cycle of the reaction. In the case of cubic nanoparticles, the amount of cubic nanoparticles decreases by 39 +/- 5\% after the first cycle and by 66 +/- 5\% after the second cycle compared to before the reaction. After the first and second cycles of the reaction, there are a greater percentage of distorted tetrahedral and distorted cubic nanoparticles present. The rate of the dissolution of the surface Pt atoms is faster for the tetrahedral nanoparticles than for the cubic nanoparticles. This suggests that tetrahedral nanoparticles, with their sharp corners and edges, are more sensitive and more liable to shape changes during nanocatalysis. The presence of just hexacyanoferrate ions in the solution with the nanoparticles is found to increase the amount of distorted tetrahedral and distorted cubes present much more than during the reaction. The presence of only the thiosulfate ions does not seem to affect the size or shape distribution which might result from the capping ability of this anion and thus protects the nanoparticles.},
	isbn = {1520-6106},
	doi = {10.1021/jp0493780},
	author = {Narayanan, Radha and El-Sayed, Mostafa A}
}
@article {1180,
	title = {Eu3+ binding to europium-regenerated bacteriorhodopsin upon delipidation and monomerization},
	journal = {Febs Letters},
	volume = {562},
	number = {1-3},
	year = {2004},
	note = {Heyes, CD Reynolds, KB El-Sayed, MA},
	month = {Mar},
	pages = {207-210},
	abstract = {We have studied the effect of monomerization of the purple membrane lattice, as well as removal of 75\% of the lipids, on the binding properties of Eu3+ ions. We found that delipidation and monomerization do not cause the cations to lose their binding ability to the protein. This suggests that the three most strongly bound Eu3+ cations do not bind to the lipids, but directly bind to the protein. Furthermore, we found that delipidation actually causes a slight increase in the binding affinity. This is likely a result of reduced aggregation of europium-regenerated bacteriorhodopsin (bR) upon lipid removal causing more exposure of the binding sites to the Eu3+ cations. These results, taken with those from our previous publication [Heyes and El-Sayed, Biophys. J. 85 (2003) 426-434], might suggest that the cations remain bound upon delipidation of bR, but have no effect on the function. This is discussed with respect to the role of cations in the function of native bR. (C) 2004 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.},
	isbn = {0014-5793},
	doi = {10.1016/s0014-5793(04)00182-6},
	author = {Heyes, C D and Reynolds, K. B. and El-Sayed, Mostafa A}
}
@article {1186,
	title = {Effect of catalysis on the stability of metallic nanoparticles: Suzuki reaction catalyzed by PVP-palladium nanoparticles},
	journal = {Journal of the American Chemical Society},
	volume = {125},
	number = {27},
	year = {2003},
	note = {Narayanan, R El-Sayed, MA},
	month = {Jul},
	pages = {8340-8347},
	abstract = {The small size of nanoparticles makes them attractive in catalysis due to their large surface-to-volume ratio. However, being small raises questions about their stability in the harsh chemical environment in which these nanoparticles find themselves during their catalytic function. In the present work, we studied the Suzuki reaction between phenylboronic acid and iodobenzene catalyzed by PVP-Pd nanoparticles to investigate the effect of catalysis, recycling, and the different individual chemicals on the stability and catalytic activity of the nanoparticles during this harsh reaction. The stability of the nanoparticles to the different perturbations is assessed using TEM, and the changes in the catalytic activity are assessed using HPLC analysis of the product yield. It was found that the process of refluxing the nanoparticles for 12 h during the Suzuki catalytic reaction increases the average size and the width of the distribution of the nanoparticles. This was attributed to Ostwald ripening in which the small nanoparticles dissolve to form larger nanoparticles. The kinetics of the change in the nanoparticle size during the 12 h period show that the nanoparticles increase in size during the beginning of the reaction and level off toward the end of the first cycle. When the nanoparticles are recycled for the second cycle, the average size decreases. This could be due to the larger nanoparticles aggregating and precipitating out of solution. This process could also explain the observed loss of the catalytic efficiency of the nanoparticles during the second cycle. It is also found that the addition of biphenyl to the reaction mixture results in it poisoning the active sites and giving rise to a low product yield. The addition of excess PVP stabilizer to the reaction mixture seems to lead to the stability of the nanoparticle surface and size, perhaps due to the inhibition of the Ostwald ripening process. This also decreases the catalytic efficiency of the nanoparticles due to capping of the nanoparticle surface. The addition of phenylboronic acid is found to lead to the stability of the size distribution as it binds to the particle surface through the O- of the OH group and acts as a stabilizer. Iodobenzene is found to have no effect and thus probably does not bind strongly to the surface during the catalytic process. These two results might have an implication on the catalytic mechanism of this reaction.},
	isbn = {0002-7863},
	doi = {10.1021/ja035044x},
	author = {Narayanan, Radha and El-Sayed, Mostafa A}
}
@article {1185,
	title = {Effect of catalytic activity on the metallic nanoparticle size distribution: Electron-transfer reaction between Fe(CN)(6) and thiosulfate ions catalyzed by PVP-platinum nanoparticles},
	journal = {Journal of Physical Chemistry B},
	volume = {107},
	number = {45},
	year = {2003},
	note = {Narayanan, R El-Sayed, MA},
	month = {Nov},
	pages = {12416-12424},
	abstract = {The electron-transfer reaction between hexacyanoferrate(III) ions and thiosulfate ions is known to be catalyzed by platinum nanoparticles. In the present study, the stability and catalytic activity of the PVP-Pt nanoparticle during its catalytic function for this electron-transfer reaction is studied. The stability of the nanoparticles after various perturbations was assessed using TEM, and the kinetics of the reaction was followed using absorption spectroscopy. The studies were conducted on four different concentrations of PVP-Pt nanoparticles. It was found that the average size and width of the PVP-Pt nanoparticles decrease slightly after the first and second cycles of the electron-transfer reaction. The size and size distribution width do not change in the presence of only the thiosulfate reactant, whereas the presence of only the hexacyanoferrate reactant results in a reduction of the nanoparticle size. The reduction in the nanoparticle size in the presence of hexacyanoferrate(HI) ions is proposed to result from the dissolution of surface Pt atoms through complexation with the strong cyanide ligand. Thiosulfate ions bind to the nanoparticle surface and act as a capping material, resulting in the stability of the nanoparticles. Judging from these observations, it is possible that the mechanism of this catalytic reaction involves the thiosulfate ions binding to the free sites on the surface of the nanoparticles, followed by reaction with hexacyanoferrate ions approaching the nanoparticle surface from the solution. Conducting the reaction with the nanoparticles preexposed to thiosulfate results in very little change in the centers and widths of the size distributions of the nanoparticles, thus suggesting that thiosulfate ions bind to the nanoparticle surface and inhibit desorption of Pt atoms by hexacyanoferrate(III) ions. The kinetics of the electron-transfer reaction during the first and second cycles is similar. The activation energy of the nanoparticle catalytic reaction is found to decrease linearly with increasing nanoparticle concentration during both the first and second cycles. If increasing the nanoparticle concentration leads to more aggregation, then these results suggest that the aggregated Pt has greater catalytic activity than the individual nanoparticles.},
	isbn = {1520-6106},
	doi = {10.1021/jp035647v},
	author = {Narayanan, Radha and El-Sayed, Mostafa A}
}
@article {1202,
	title = {The effect of surface adsorption on the hyper-Rayleigh scattering of large and small CdSe nanoparticles},
	journal = {Chemical Physics Letters},
	volume = {363},
	number = {5-6},
	year = {2002},
	note = {Landes, C Braun, M El-Sayed, MA},
	month = {Sep},
	pages = {465-470},
	abstract = {Hyper-Rayleigh scattering is used to compare the effect of the addition of n-butylamine to large (3.2 nm) and small (1.6 nm) Use nanoparticles (NPs). It is found that although the adsorption of n-butylamine on large NPs enhances their nonlinear optical response, it has the opposite effect when adsorbed on the small nanoparticles for which the amine adsorption was found previously to induce structural changes. This observation is consistent with an increase in the symmetry of the nanocrystal structure such as would be observed in a phase change from a 4-coordinate wurtzite crystal structure to that of a 6-coordinate zinc-blend form. (C) 2002 Published by Elsevier Science B.V.},
	isbn = {0009-2614},
	doi = {10.1016/s0009-2614(02)01169-7},
	author = {Landes, Christy F. and Braun, Markus and El-Sayed, Mostafa A}
}
@article {1206,
	title = {The effect of metal cation binding on the protein, lipid and retinal isomeric ratio in regenerated bacteriorhodopsin of purple membrane},
	journal = {Photochemistry and Photobiology},
	volume = {73},
	number = {5},
	year = {2001},
	note = {Wang, JP El-Sayed, MA},
	month = {May},
	pages = {564-571},
	abstract = {The effect of metal cation binding on bacteriorhodopsin (bR) in purple membrane has been examined using in situ attenuated total reflection-Fourier transform infrared difference spectroscopy in aqueous media. It is known that adding metal cations to deionized bR regenerates the purple state from its blue state and recovers the proton pump function, During this process, infrared spectral changes in the frequency region of 1800-1000 cm(-1) are monitored. The results reveal that metal cation binding affects the protein conformation, the retinal isomeric composition as well as lipid head groups. It is also observed that metal cation binding induces conformational changes in the alpha (1)-helix region of bR, converting the portion of its alpha (1)-helical domain into beta -turn or disordered coil, In addition, the influence of Ho3+ binding on the protein and lipid is observed to be larger than that of Ca2+, These results suggest that some of the metal cation binding sites are on the membrane lipid domain, while others could be on the intrahelical domain or interhelical loops where the Asp and Glu are located (binding with their COO- groups). Our results also suggest that the removal of the C-terminal of bR increase the accessibility of the binding site of metal cations, which affects protein conformational structure. All these observations are discussed in terms of the two proposals given in the literature regarding the metal cation binding sites.},
	isbn = {0031-8655},
	doi = {10.1562/0031-8655(2001)073<0564:teomcb>2.0.co;2},
	author = {Wang, Jianping and El-Sayed, Mostafa A}
}
@article {1214,
	title = {The effect of stabilizers on the catalytic activity and stability of Pd colloidal nanoparticles in the Suzuki reactions in aqueous solution},
	journal = {Journal of Physical Chemistry B},
	volume = {105},
	number = {37},
	year = {2001},
	note = {Li, Y El-Sayed, MA},
	month = {Sep},
	pages = {8938-8943},
	abstract = {Transition metal nanoparticles used in catalysis in solution are stabilized by capping the surfaces that are supposed to be used for catalysis. Determining, how these two properties, that is, the catalytic activity and stability of nanoparticles, change as different capping materials are used is the aim of this work. Pd nanoparticles prepared by the reduction of metal salts in the presence of three different stabilizers-hydroxyl-terminated poly(amido-amine) (PAMAM) dendrimers (Gn-OH, where Gn represents the nth generation), block copolymer polystyrene-b-poly(sodium acrylate) and poly (N-vinyl-2-pyrrolidone) (PVP)-are used as catalysts in the Suzuki reactions in an aqueous medium to investigate the effects of these stabilizers on the metallic nanoparticle catalytic activity and stability. The stability of the Pd nanoparticles is measured by the tendency of the nanoparticles to give Pd black powder after the catalytic reaction. The Suzuki reaction is a good "acid test" for examining the stability of these nanoparticles, as it takes place when refluxed at about 100 degreesC for 24 h. The stability is found to depend on the type of the stabilizer, the reactant, and the base used in the reaction system. Pd nanoparticles stabilized by block copolymer, G3 dendrimer, and PVP are found to be efficient catalysts for the Suzuki reactions between phenylboronic acid (or 2-thiopheneboronic acid) and iodobenzene. G4 dendrimer is found to be an effective stabilizer; however, strong encapsulation of Pd particles in the dendrimer results in a loss of catalytic activity. The Suzuki reactions between arylboronic acids and bromoarenes catalyzed by Pd nanoparticles result in byproducts due to the homo-coupling of bromoarenes. A summary of the catalytic activity and stability of the Pd nanoparticles in these different systems is tabulated. As one would expect. these two properties are anticorrelated that is the most stable is the least catalytic active.},
	isbn = {1089-5647},
	doi = {10.1021/jp010904m},
	author = {Li, Y. and El-Sayed, Mostafa A}
}
@article {1217,
	title = {Effect of temperature, pH, and metal ion binding on the secondary structure of bacteriorhodopsin: FT-IR study of the melting and premelting transition temperatures},
	journal = {Biochemistry},
	volume = {40},
	number = {39},
	year = {2001},
	note = {Heyes, CD El-Sayed, MA},
	month = {Oct},
	pages = {11819-11827},
	abstract = {We have measured the temperature dependence of the FT-IR spectra of bacteriorhodopsin (bR) as a function of the pH and of the divalent cation regeneration with Ca2+ and Mg2+. It has been found that although the irreversible melting transition shows a strong dependence on the pH of the native bR, the premelting reversible transition at 78-80 degreesC shows very little variation over the pH range studied. It is further shown that the acid blue bR shows a red-shifted amide I spectrum at physiological temperature, which shows a more typical alpha -helical frequency component at 1652 cm(-1) and could be the reason for the observed reduction of its melting temperature and lack of an observed premelting transition. Furthermore, the thermal transitions for Ca2+- and Mg2+-regenerated bR (Ca-bR and Mg-bR, respectively) each show a premelting transition at the same 78-80 degreesC temperature as the native purple membrane, but the irreversible melting transition has a slight dependence on the cation identity. The pH dependence of the Ca2+-regenerated bR is studied, and neither transition varies over the pH range studied. These results are discussed in terms of the cation contribution to the secondary structural stability in bR.},
	isbn = {0006-2960},
	doi = {10.1021/bi002594o},
	author = {Heyes, C D and El-Sayed, Mostafa A}
}
@article {1209,
	title = {Evidence for bilayer assembly of cationic surfactants on the surface of gold nanorods},
	journal = {Langmuir},
	volume = {17},
	number = {20},
	year = {2001},
	note = {Nikoobakht, B El-Sayed, MA},
	month = {Oct},
	pages = {6368-6374},
	abstract = {The surface structure of gold nanorods (NRs) capped with cationic surfactants in water was studied by FTIR, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). For gold nanorods, the FTIR results show the formation of new bands, which indicate binding of the surfactant headgroup to the surface of the NR. These bands are stable at temperatures as high as 350 degreesC. For a surfactant mixture (used as capping material), TGA shows a weak weight loss peak at 235 degreesC and a strong peak at 298 degreesC assigned to the surfactant molecules in monomer and aggregated forms, respectively. For gold nanorods, three weight loss peaks at about 230, 273, and 344 degreesC are observed. For gold nanospheres (NSs), TGA shows a strong mass loss at 225 degreesC and two weak mass loss peaks at 255 and 288 degreesC. The released material after combustion in the TGA process was analyzed by FTIR spectroscopy and found to be CO2. Our results suggest the following for both NRs and NSs: (1) There are two different binding modes for the surfactant molecules capping these nanoparticles. (2) Surfactant molecules form a bilayer structure around the gold nanoparticles in which the inner layer is bound to the gold surface via the surfactant headgroups. (3) With increase of the temperature, the outer layer desorbs at lower temperature and consequently the inner layer leaves the surface at higher temperature. (4) The higher desorption temperature of the bilayer in the NRs compared to NSs is explained in terms of the difference in packing of the surfactant molecules and their adsorption energy to the different facets present in these nanoparticles. (5) TEM results suggest that the shape transformation of NRs to NSs occurs as the inner layer is released from the surface. (6) The CH2 rocking mode at 720 cm(-1) suggests that the methylene chains have free rotation and surfactants are packed in a hexagonal structure.},
	isbn = {0743-7463},
	doi = {10.1021/la010530o},
	author = {Nikoobakht, Babak and El-Sayed, Mostafa A}
}
@article {1222,
	title = {The effect of the protein conformation change on bacteriorhodopsin photocycle},
	journal = {Biophysical Journal},
	volume = {78},
	number = {1},
	year = {2000},
	note = {Wang, JP El-Sayed, MAPart 2},
	month = {Jan},
	pages = {159A-159A},
	isbn = {0006-3495},
	author = {Wang, Jianping and El-Sayed, Mostafa A}
}
@article {1234,
	title = {Effect of different capping environments on the optical properties of CdS nanoparticles in reverse micelles},
	journal = {International Journal of Quantum Chemistry},
	volume = {72},
	number = {4},
	year = {1999},
	note = {Zou, BS Little, RB Wang, JP El-Sayed, MA},
	month = {Apr},
	pages = {439-450},
	abstract = {CdS(E = 2.5 eV) nanoparticles were synthesized in reversed micelles and capped with materials of different band gaps and charge compensation ability: Cd(OH)(2) (4.0 eV), ZnS (3.2 eV), and CdO (2.3 eV). The preparations allowed the examination and comparison of the efficiencies of confinement of the electron and hole by the various capping materials. The absorption and emission spectra of the capped CdS nanoparticles suggest the following: (1) Efficient capping and strong quantum confinement are observed for CdS particles of small size (< 3.8 nm), showing well-resolved photoexcitation spectra; (2) the confinement efficiency improves with capping thickness; (3) although ZnS has smaller band gap than Cd(OH)(2), it was more efficient in surface-charge compensation and it is the best capping agent of the three materials; and (4) the similar band gaps of CdO and CdS resulted spectroscopically in strong mixing between the excited states of these materials. (C) 1999 John Wiley \& Sons, Inc.},
	isbn = {0020-7608},
	doi = {10.1002/(sici)1097-461x(1999)72:4<439::aid-qua27>3.0.co;2-q},
	author = {Zou, Bingsuo and Little, Reginald and Wang, Jianping and El-Sayed, Mostafa A}
}
@article {1247,
	title = {The effect of low and high temperature anneals on the hydrogen content and passivation of Si surface coated with SiO2 and SiN films},
	journal = {Journal of the Electrochemical Society},
	volume = {146},
	number = {5},
	year = {1999},
	note = {Ebong, A Doshi, P Narasimha, S Rohatgi, A Wang, J El-Sayed, MA},
	month = {May},
	pages = {1921-1924},
	abstract = {A detailed comparison of the passivation quality and its dependence on the low and high temperature anneals is presented for various promising Si surface passivation schemes. The passivation schemes investigated in this study include: conventional furnace oxide (CFO), rapid thermal oxide (RTO), belt line oxide (BLO), plasma deposited oxide (PDO), SiN deposited by plasma enhanced chemical vapor deposition (PECVD), CFO/SiN, RTO/SiN, BLO/SiN, PDO/SiN, and RTO/PDO. Passivated low resistivity (1 Ohm cm) p-type silicon samples were subjected to three annealing treatments: (a) 400 degrees C in forming gas (FGA), (b) 730 degrees C in air, and (c) 850 degrees C in air, to simulate heat-treatments, which are typically used for contact anneal, front ohmic contacts, and back surface field formation, respectively, for screen printed silicon solar cells. It is found that the passivation quality of PDO, SiN, RTO, and CFO single layers improves significantly after the 400 degrees C FGA and 730 degrees C thermal cycles with RTO resulting in the lowest surface recombination velocities (S-eff) of 154 and 405 cm/s, respectively. Silicon wafers coated with belt oxide (BLO and BLO/SiN) did not show any improvement in S-eff, which remained at 5000 cm/s due to the inferior quality of BLO formed in compressed air. The oxide/ nitride stack passivation is found to be far superior to single-layer passivation resulting in S-eff Of 70 cm/s for the RTO/SiN scheme after the two high temperature anneals (850 and 730 degrees C). The hydrogen concentration measurements by Fourier transform infrared spectroscopy show a greater decrease in the hydrogen content in the annealed RTO/SiN stack compared to the as-deposited SiN single layer after the 730 and 850 degrees C anneals. A combination of reduced hydrogen content and very low S-eff in the RTO/SiN stack suggests that the release of hydrogen from SiN during the anneal further passivates the RTO/Si interface underneath. (C) 1999 The Electrochemical Society. S0013-4651(98)08-117-8. All rights reserved.},
	isbn = {0013-4651},
	doi = {10.1149/1.1391866},
	author = {Ebong, A. and Doshi, P. and Narasimha, S. and Rohatgi, A. and Wang, Jianping and El-Sayed, Mostafa A}
}
@article {1244,
	title = {Electron dynamics in gold and gold-silver alloy nanoparticles: The influence of a nonequilibrium electron distribution and the size dependence of the electron-phonon relaxation},
	journal = {Journal of Chemical Physics},
	volume = {111},
	number = {3},
	year = {1999},
	note = {Link, S Burda, C Wang, ZL El-Sayed, MA},
	month = {Jul},
	pages = {1255-1264},
	abstract = {Electron dynamics in gold nanoparticles with an average diameter between 9 and 48 nm have been studied by femtosecond transient absorption spectroscopy. Following the plasmon bleach recovery after low power excitation indicates that a non-Fermi electron distribution thermalizes by electron-electron relaxation on a time scale of 500 fs to a Fermi distribution. This effect is only observed at low excitation power and when the electron distribution is perturbed by mixing with the intraband transitions within the conduction band (i.e., when the excitation wavelength is 630 or 800 nm). However, exciting the interband transitions at 400 nm does not allow following the early electron thermalization process. Electron thermalization with the lattice of the nanoparticle by electron-phonon interactions occurs within 1.7 ps under these conditions, independent of the excitation wavelength. In agreement with the experiments, simulations of the optical response arising from thermalized and nonthermalized electron distributions show that a non-Fermi electron distribution leads to a less intense bleach of the plasmon absorption. Furthermore, the difference between the response from the two electron distributions is greater for small temperature changes of the electron gas (low excitation powers). No size dependence of the electron thermalization dynamics is observed for gold nanoparticles with diameters between 9 and 48 nm. High-resolution transmission electron microscopy (HRTEM) reveals that these gold nanoparticles possess defect structures. The effect of this on the electron-phonon relaxation processes is discussed. 18 nm gold-silver alloy nanoparticles with a gold mole fraction of 0.8 are compared to 15 nm gold nanoparticles. While mixing silver leads to a blue-shift of the plasmon absorption in the ground-state absorption spectrum, no difference is observed in the femtosecond dynamics of the system. (C) 1999 American Institute of Physics. [S0021-9606(99)71427-3].},
	isbn = {0021-9606},
	doi = {10.1063/1.479310},
	author = {Link, Stephan and Burda, Clemens and Wang, Z.L. and El-Sayed, Mostafa A}
}
@article {1291,
	title = {Electron Shuttling Across the Interface of CdSe Nanoparticles Monitored by Femtosecond Laser Spectroscopy},
	journal = {The Journal of Physical Chemistry B},
	volume = {103},
	year = {1999},
	note = {doi: 10.1021/jp9843050},
	month = {1999},
	pages = {1783 - 1788},
	publisher = {American Chemical Society},
	abstract = {The formation and decay of the optical hole (bleach) for 4 nm CdSe nanoparticles (NPs) with adsorbed electron acceptors (1,4-benzoquinone and 1,2-naphthoquinone) and the rise and decay of the reduced electron acceptors formed after interfacial electron transfer from the CdSe NPs were investigated by femtosecond laser spectroscopy. The ultrashort (200?400 fs) rise times of the bleach at the band-gap energy of the CdSe NP as well as of the acceptor radical anion are found to increase with increasing the excitation energy. This suggests that the electron transfer from the CdSe NP to the quinone electron acceptor occurs after thermalization of the excited hot electrons. The decay times of the transient absorption for the electron acceptor radical anions are found to be comparable to that of the CdSe NP bleach recovery time (3 ps). This suggests that the surface quinones shuttle the electron from the conduction band to the valence band of the excited NP. We contrast this behavior with the excited-state dynamics of the recently investigated CdS?MV2+ system in which the electron acceptor does not shuttle the accepted electron back to the hole in CdS.The formation and decay of the optical hole (bleach) for 4 nm CdSe nanoparticles (NPs) with adsorbed electron acceptors (1,4-benzoquinone and 1,2-naphthoquinone) and the rise and decay of the reduced electron acceptors formed after interfacial electron transfer from the CdSe NPs were investigated by femtosecond laser spectroscopy. The ultrashort (200?400 fs) rise times of the bleach at the band-gap energy of the CdSe NP as well as of the acceptor radical anion are found to increase with increasing the excitation energy. This suggests that the electron transfer from the CdSe NP to the quinone electron acceptor occurs after thermalization of the excited hot electrons. The decay times of the transient absorption for the electron acceptor radical anions are found to be comparable to that of the CdSe NP bleach recovery time (3 ps). This suggests that the surface quinones shuttle the electron from the conduction band to the valence band of the excited NP. We contrast this behavior with the excited-state dynamics of the recently investigated CdS?MV2+ system in which the electron acceptor does not shuttle the accepted electron back to the hole in CdS.},
	isbn = {1520-6106},
	doi = {doi: 10.1021/jp9843050},
	url = {http://dx.doi.org/10.1021/jp9843050},
	author = {Burda, Clemens and Green, T.C. and Link, Stephan and El-Sayed, Mostafa A}
}
@article {1263,
	title = {Effect of Lattice Energy Mismatch on the Relative Mass Peak Intensities of Mixed Alkali Halide Nanocrystals},
	journal = {The Journal of Physical Chemistry A},
	volume = {101},
	year = {1997},
	note = {doi: 10.1021/jp962045l},
	month = {1997},
	pages = {690 - 693},
	publisher = {American Chemical Society},
	abstract = {The relative mass peak intensity distribution of the [M14-nAnI13]+ mixed alkali halide nanocrystals containing a ?magic? number of 14 metal cations (M and A) and 13 iodide anions is examined. These nanocrystals were generated through sputtering of mixed solid alkali halides using fast atom bombardment and analyzed by use of a double-focusing sector field mass spectrometer. The mass peak intensities of mixed cluster ions composed of two different metals relative to the ?pure? nanocrystals (containing one or the other metal) are compared for two types of mixed cluster ions:? one with small lattice energy mismatch, i.e., [Rb14-nKnI13]+ cluster ions, and the other type with large lattice energy mismatch, i.e., [Cs14-nAnI13]+ cluster ions where A is either Na, K, or Rb. In contrast to what was previously1 found for clusters with small energy mismatch in which the rate of formation (which depends on the possible number of isomers that each mixed cluster ion can have) determines the relative intensities of mass peaks, the rate of evaporation (i.e., the cluster instability) determines the relative mass peak intensities in salts with relatively large lattice energy mismatch. These results are consistent with our previously proposed kinetic model for the formation and decay of these clusters.The relative mass peak intensity distribution of the [M14-nAnI13]+ mixed alkali halide nanocrystals containing a ?magic? number of 14 metal cations (M and A) and 13 iodide anions is examined. These nanocrystals were generated through sputtering of mixed solid alkali halides using fast atom bombardment and analyzed by use of a double-focusing sector field mass spectrometer. The mass peak intensities of mixed cluster ions composed of two different metals relative to the ?pure? nanocrystals (containing one or the other metal) are compared for two types of mixed cluster ions:? one with small lattice energy mismatch, i.e., [Rb14-nKnI13]+ cluster ions, and the other type with large lattice energy mismatch, i.e., [Cs14-nAnI13]+ cluster ions where A is either Na, K, or Rb. In contrast to what was previously1 found for clusters with small energy mismatch in which the rate of formation (which depends on the possible number of isomers that each mixed cluster ion can have) determines the relative intensities of mass peaks, the rate of evaporation (i.e., the cluster instability) determines the relative mass peak intensities in salts with relatively large lattice energy mismatch. These results are consistent with our previously proposed kinetic model for the formation and decay of these clusters.},
	isbn = {1089-5639},
	doi = {doi: 10.1021/jp962045l},
	url = {http://dx.doi.org/10.1021/jp962045l},
	author = {Ahmadi, Temer S. and El-Sayed, Mostafa A}
}
@article {868,
	title = {Electron Dynamics of Passivated Gold Nanocrystals Probed by Subpicosecond Transient Absorption Spectroscopy},
	journal = {The Journal of Physical Chemistry B},
	volume = {101},
	year = {1997},
	note = {doi: 10.1021/jp962923f},
	month = {1997},
	pages = {3713 - 3719},
	publisher = {American Chemical Society},
	abstract = {The electronic dynamics of gold nanocrystals, passivated by a monolayer of alkylthiol(ate) groups, were studied by transient spectroscopy after excitation with subpicosecond laser pulses. Three solution-phase gold samples with average particle size of 1.9, 2.6, and 3.2 nm with size distribution less than 10\% were used. The photoexcitation in the intraband (surface plasmon region) leads to the heating of the conduction electron gas and its subsequent thermalization through electron?electron and electron?phonon interaction. The results are analyzed in terms of the contribution of the equilibrated ?hot? electrons to the surface plasmon resonance of gold. A different spectral response was observed for different sizes of gold nanoparticles. The results were compared to the dynamics of the large (30 nm diameter) gold nanocrystals colloidal solution. The size-dependent spectral changes are attributed to the reduction of the density of states for small nanoparticles. The observed variation in the kinetics of the cooling process in gold nanoparticles with changing the laser intensity is attributed to the temperature dependence of the heat capacity of the electron gas.The electronic dynamics of gold nanocrystals, passivated by a monolayer of alkylthiol(ate) groups, were studied by transient spectroscopy after excitation with subpicosecond laser pulses. Three solution-phase gold samples with average particle size of 1.9, 2.6, and 3.2 nm with size distribution less than 10\% were used. The photoexcitation in the intraband (surface plasmon region) leads to the heating of the conduction electron gas and its subsequent thermalization through electron?electron and electron?phonon interaction. The results are analyzed in terms of the contribution of the equilibrated ?hot? electrons to the surface plasmon resonance of gold. A different spectral response was observed for different sizes of gold nanoparticles. The results were compared to the dynamics of the large (30 nm diameter) gold nanocrystals colloidal solution. The size-dependent spectral changes are attributed to the reduction of the density of states for small nanoparticles. The observed variation in the kinetics of the cooling process in gold nanoparticles with changing the laser intensity is attributed to the temperature dependence of the heat capacity of the electron gas.},
	isbn = {1520-6106},
	url = {http://dx.doi.org/10.1021/jp962923f},
	author = {Logunov, Stephan L. and Ahmadi, Temer S. and El-Sayed, Mostafa A and Khoury, J. T. and Whetten, R. L.}
}
@article {1266,
	title = {Effect of Binding of Lanthanide Ions on the Bacteriorhodopsin Hexagonal Structure:  An X-ray Study},
	journal = {The Journal of Physical Chemistry},
	volume = {100},
	year = {1996},
	note = {doi: 10.1021/jp960741f},
	month = {1996},
	pages = {12002 - 12007},
	publisher = {American Chemical Society},
	abstract = {The effect of the binding of trivalent lanthanide metal cations (Eu3+, Ho3+, and Dy3+) on the hexagonal structure of bacteriorhodopsin (bR) is investigated at different pH using x-Ray diffraction to examine films made by slow evaporation of the corresponding regenerated bR. It is observed that the lanthanide-regenerated bR (at a ratio of 2:1 metal ion to bR) does not form a 2D structure isomorphous to that of native bR or Ca2+-regenerated samples at low sample pH. The native bR hexagonal structure is recovered by titration of the sample with sodium hydroxide. The pH at which the hexagonal structure is recovered depends on the charge density of the lanthanide ion used for the regeneration. The higher the charge density of the ion, the higher the pH at which an isomorphous lattice is formed. A model is proposed in which at normal or low pH a complex bidentate and monodentate type binding (which disrupts the lattice hexagonal structure) exists between a lanthanide ion, the O- of PO2- groups, and/or the amino acid residues. At high pH, complexation with OH- takes place, which converts this binding to a simple monodentate type complex that leads to the recovery of the lattice structure. An equation is derived for the pH at which this conversion takes place and is found to be proportional to the binding constant of the lanthanide ions to the O- of the PO2- groups or the amino acid residues and inversely proportional to the binding constant of the lanthanide ion to the OH- groups. This predicts an increase of conversion pH with the charge density of the lanthanide ion, as observed.},
	isbn = {0022-3654},
	doi = {doi: 10.1021/jp960741f},
	url = {http://dx.doi.org/10.1021/jp960741f},
	author = {Griffiths, Jennifer A. and El-Sayed, Mostafa A and Capel, Malcom}
}
@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 {1265,
	title = {Effects of rapid thermal anneal on refractive index and hydrogen content of plasma-enhanced chemical vapor deposited silicon nitride films},
	journal = {J. Appl. Phys.Journal of Applied Physics},
	volume = {80},
	year = {1996},
	month = {1996},
	pages = {5384},
	publisher = {AIP},
	abstract = {The objective of this paper is to understand and quantify the effects of rapid thermal anneal (RTA) on refractive index, thickness, and hydrogen content of plasma-enhanced, chemical vapor-deposited (PECVD) silicon nitride films. It is shown that RTA is more effective than identical furnace anneal. A threshold in as-deposited refractive index value is found, above which the index of a silicon nitride film increases, while the thickness and bonded hydrogen content decreases as result of the RTA. In addition, the magnitude of increase in the index is proportional to the as-deposited index value. The threshold index value increases with the increase in silicon nitride deposition temperature. A direct correlation is found between the annealing-induced increase in refractive index and the corresponding decrease in total bonded hydrogen concentration in the PECVD silicon nitride films. Finally, it is shown that the release of bonded hydrogen from the film can passivate defects in the underlying silicon substrate and increase the performance of silicon devices such as solar cells. },
	keywords = {ANNEALING, CRYSTAL DEFECTS, CVD, DESORPTION, HYDROGEN, IMPURITIES, REFRACTIVE INDEX, SILICON NITRIDES, THICKNESS, THIN FILMS},
	doi = {10.1063/1.363480},
	url = {http://dx.doi.org/10.1063/1.363480},
	author = {Cai, L.},
	editor = {Rohatgi, A. and Yang, Difei and El-Sayed, Mostafa A}
}
@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 {876,
	title = {The effect of different metal cation binding on the proton pumping in bacteriorhodopsin},
	journal = {Israel journal of chemistry},
	volume = {35},
	year = {1995},
	pages = {465-474},
	publisher = {Weizmann},
	abstract = {The first section of this paper is a detailed summary of studies made by us and others on metal cations binding to deionized bacteriorhodopsin (dIbR) and its variants. Our studies include the luminescence experiments of Eu3+ binding to dIbR and potentiometric studies of Ca2+ binding to dIbR, to deionized bR mutants, to bacterioopsin, and to dIbR with its C-terminus removed. The results suggest the presence of two classes of binding sites, one class has two high-affinity constants, and one has one low-affinity constant. For Ca2+ binding, there is one metal cation in each of the two high-affinity sites which are coupled to the charged aspartates 85 and 212 (known to be in the retinal cavity) but not coupled to each other. The low-affinity class can accommodate 0-6 Ca2+ ions and most of them are bound to the surface. Mg2+ has a slightly smaller value for its binding constant to the highest-affinity site. Thus, one expects more Ca2+ than Mg2+ bound to the two high-affinity sites. In the second section, we summarize our recent study on the effect of metal cation charge density (Ca2+, Mg2+, Eu3+, Tb3+, Ho3+, Dy3+) on the kinetics of both Schiff base deprotonation and proton transport to the extracellular surface. For all metal cations, the apparent rate constant of the slow components of the deprotonation process is the same as that for the transport process at 22 degrees C. The temperature studies, however, show this apparent equality to be fortuitous and to result from cancellation of the contribution of the energy and entropy of activation. Thus, while the entropy of activation is positive for the deprotonation process, it is negative for the proton transport process. These kinetic parameters depend weakly on the charge density, but in an opposite sense for the two processes. These results suggest that the deprotonation is not the rate-limiting step for the proton transport process. A possible mechanism is proposed in which a hydrated metal cation is used to induce the deprotonation of the protonated Schiff base and to dissociate one of its H2O molecules to donate the proton in the L-->M process.},
	isbn = {0021-2148},
	author = {El-Sayed, Mostafa A and Yang, Difei and Yoo, Seoung-Kyo and Zhang, N.}
}
@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.}
}
