@article {1638,
	title = {Real-Time Tracking of Autophagy Process in Living Cells Using Plasmonically Enhanced Raman Spectroscopy of Fucoidan-Coated Gold Nanoparticles},
	journal = {Journal of Materials Chemistry B},
	year = {2018},
	author = {Jang, H and K. Kang and El-Sayed, M. A.}
}
@article {1614,
	title = {Facile size-controlled synthesis of fucoidan-coated gold nanoparticles and cooperative anticancer effect with doxorubicin},
	journal = {Journal of Materials Chemistry B},
	year = {2017},
	author = {Jang, H and et al.}
}
@article {1618,
	title = {Dual-Responsive Reversible Plasmonic Behavior of Core{\textendash}Shell Nanostructures with pH-Sensitive and Electroactive Polymer Shells},
	journal = {Chemistry of Materials},
	year = {2016},
	author = {Jeon, JW 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 {1584,
	title = {Hyperoxia Induces Intracellular Acidification in Neonatal Mouse Lung Fibroblasts: Real-Time Investigation Using Plasmonically Enhanced Raman Spectroscopy},
	journal = {Journal of the American Chemical Society},
	volume = {138},
	year = {2016},
	pages = {3779{\textendash}3788},
	author = {Panikkanvalappil, Sajanlal R. and James, Masheika and Hira, Steven M and Mobley, James and Jilling, Tamas and Ambalavanan, Namasivayam and El-Sayed, Mostafa A.}
}
@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 {1384,
	title = {Bandgap bowing in Ta-W-O system for efficient solar energy conversion: Insights from density functional theory and X-ray diffraction},
	journal = {Applied Physics Letters},
	volume = {103},
	number = {13},
	year = {2013},
	note = {Nashed, Ramy Alamgir, Faisal M. Jang, Seung Soon Ismail, Yehea El-Sayed, Mostafa A. Allam, Nageh K.},
	month = {Sep},
	isbn = {0003-6951},
	doi = {10.1063/1.4823543},
	author = {Nashed, R. and Alamgir, F. M. and Jang, S. S. and Ismail, Y. and El-Sayed, M. A. and Allam, N. K.}
}
@article {1079,
	title = {Plasmonic Spheroidal Metal Nanoshells Showing Larger Tunability and Stronger Near Fields Than Their Spherical Counterparts: An Effect of Enhanced Plasmon Coupling},
	journal = {Journal of Physical Chemistry Letters},
	volume = {2},
	number = {5},
	year = {2011},
	note = {Hooshmand, Nasrin Jain, Prashant K. El-Sayed, Mostafa A.},
	month = {Mar},
	pages = {374-378},
	abstract = {Two of the most tunable nanostructure geometries for nanoplas monics include the metal nanoshell structure and the spheroidal geometry. We systematically investigate the effect of combining both geometries within the same nanostructure. Localized surface plasmon resonances (LSPRs) of spheroidal gold nanoshells are simulated as a function of their aspect ratio. The long-axis LSPR mode of a spheroidal nanoshell red shifts with decreasing shell thickness, similar to a spherical nanoshell. A higher aspect ratio spheroidal nanoshell shows a larger fractional LSPR red shift for the same thickness normalized by core dimensions. This is because coupling between the inner and outer surface plasmons of the nanoshell is stronger for the elongated spheroidal geometry as compared to that for the spherical case, increasing in strength with increasing aspect ratio. It is the result of this enhanced plasmon coupling that spheroidal nanoshells of aspect ratio 4 are over two times more tunable than spherical nanoshells. Also, the plasmonic field enhancement is an order of magnitude larger for the spheroidal nanoshells of aspect ratio 4 as compared to spherical nanoshells. These effects observed in the spheroidal nanoshell are analogous to those in a dimer of spheroidal nanopatides.},
	isbn = {1948-7185},
	doi = {10.1021/jz200034j},
	author = {Hooshmand, N. and Jain, Prashant K and El-Sayed, Mostafa A}
}
@article {1095,
	title = {Plasmonic coupling in noble metal nanostructures},
	journal = {Chemical Physics Letters},
	volume = {487},
	number = {4-6},
	year = {2010},
	note = {Jain, Prashant K. El-Sayed, Mostafa A.},
	month = {Mar},
	pages = {153-164},
	abstract = {Noble metal nanostructures display unique and strongly enhanced optical properties due to the phenomenon of localized surface plasmon resonance (LSPR). In assemblies or complex noble metal nanostructures, individual plasmon oscillations on proximal particles can couple via their near-field interaction, resulting in coupled plasmon resonance modes, quite akin to excitonic coupling in molecular aggregates or orbital hybridization in molecules. In this frontier Letter we discuss how the coupling of plasmon modes in certain nanostructure geometries (such as nanoparticle dimers and nanoshells) allows systematic tuning of the optical resonance, and also the confinement and enhancement of the near-field, making possible improved refractive-index sensing and field-enhanced spectroscopy and photochemistry. We discuss the polarization, orientation, and distance-dependence of this near-field coupling especially the universal size-scaling of the plasmon coupling interaction. In addition to radiative properties, we also discuss the effect of inter-particle coupling on the non-radiative electron relaxation in noble metal nanostructures. (C) 2010 Elsevier B.V. All rights reserved.},
	isbn = {0009-2614},
	doi = {10.1016/j.cplett.2010.01.062},
	author = {Jain, Prashant K and El-Sayed, Mostafa A}
}
@article {1125,
	title = {Noble Metal Nanoparticle Pairs: Effect of Medium for Enhanced Nanosensing},
	journal = {Nano Letters},
	volume = {8},
	number = {12},
	year = {2008},
	note = {Jain, Prashant K. El-Sayed, Mostafa A.},
	month = {Dec},
	pages = {4347-4352},
	abstract = {In this Letter, we show using both a quasi-static model and discrete dipole approximation simulations of nanoparticle pairs that the surface plasmon resonance shift resulting from the electromagnetic coupling between noble metal nanoparticles increases with an increase in the dielectric constant of the medium. As the particle pair partners approach each other, there is an increase in the rate at which the plasmon resonance shifts in response to a medium refractive index change. Thus, the surface plasmon resonance of a plasmonic nanoparticle pair exhibits higher sensitivity to the environment/medium refractive index as compared to an isolated nanoparticle. The medium sensitivity of the particle pair is shown to increase near exponentially with a decrease in the interparticle separation between the nanoparticles. We therefore propose that enhanced plasmon resonance nanosensing may be achieved by employing coupled particles instead of colloids or arrays of noninteracting particles.},
	isbn = {1530-6984},
	doi = {10.1021/nl8021835},
	author = {Jain, Prashant K and El-Sayed, Mostafa A}
}
@article {1124,
	title = {Noble Metals on the Nanoscale: Optical and Photothermal Properties and Some Applications in Imaging, Sensing, Biology, and Medicine},
	journal = {Accounts of Chemical Research},
	volume = {41},
	number = {12},
	year = {2008},
	note = {Jain, Prashant K. Huang, Xiaohua El-Sayed, Ivan H. El-Sayed, Mostafa A.},
	month = {Dec},
	pages = {1578-1586},
	abstract = {Noble metal nanostructures attract much interest because of their unique properties, including large optical field enhancements resulting in the strong scattering and absorption of light. The enhancement in the optical and photothermal properties of noble metal nanoparticles arises from resonant oscillation of their free electrons in the presence of light, also known as localized surface plasmon resonance (LSPR). The plasmon resonance can either radiate light (Mie scattering), a process that finds great utility in optical and imaging fields, or be rapidly converted to heat (absorption); the latter mechanism of dissipation has opened up applications in several new areas. The ability to integrate metal nanoparticles into biological Systems has had greatest impact in biology and biomedicine. In this Account we discuss the plasmonic properties of gold and silver nanostructures and present examples of how they are being utilized for biodiagnostics, biophysical studies, and medical therapy. For instance, taking advantage of the strong LSPR scattering of gold nanoparticles conjugated with specific targeting molecules allows the mollecule-specific imaging and diagnosis of diseases such as cancer. We emphasize in particular how the unique tunability of the plasmon resonance properties of metal nanopartides through variation of their size, shape, composition, and medium allows chemists to design nanostructures geared for specific bio-applications. We discuss some interesting nanostructure geometries, including nanorods, nanoshells, and nanopartide pairs, that exhibit dramatically enhanced and tunable plasmon resonances, making them highly suitable for bio-applications. Tuning the nanostructure shape (e.g., nanoprisms, nanorods, or nanoshells) is another means of enhancing the sensitivity of the LSPR to the nanopartide environment and, thereby, designing effective biosensing agents. Metal nanopartide pairs or assemblies display distance-dependent plasmon resonances as a result of field coupling. A universal scaling model, relating the plasmon resonance frequency to the interpartide distance in terms of the particle size, becomes potentially useful for measuring nanoscale distances (and their changes) in biological systems. The strong plasmon absorption and photothermal conversion of gold nanoparticles has been exploited in cancer therapy through the selective localized photothermal heating of cancer cells. For nanorods or nanoshells, the LSPR can be tuned to the near-infrared region, making it possible to perform in vivo imaging and therapy. The examples of the applicators of noble metal nanostructures provided herein can be readily generalized to other areas of biology and medicine because plasmonic nanomaterials exhibit great range, versatility, and systematic tunability of their optical attributes.},
	isbn = {0001-4842},
	doi = {10.1021/ar7002804},
	author = {Jain, Prashant K and Huang, Xiaohua and El Sayed, I.H. and El-Sayed, Mostafa A}
}
@article {1127,
	title = {Plasmonic photothermal therapy (PPTT) using gold nanoparticles},
	journal = {Lasers in Medical Science},
	volume = {23},
	number = {3},
	year = {2008},
	note = {Huang, Xiaohua Jain, Prashant K. El-Sayed, Ivan H. El-Sayed, Mostafa A.},
	month = {Jul},
	pages = {217-228},
	abstract = {The use of lasers, over the past few decades, has emerged to be highly promising for cancer therapy modalities, most commonly the photothermal therapy method, which employs light absorbing dyes for achieving the photothermal damage of tumors, and the photodynamic therapy, which employs chemical photosensitizers that generate singlet oxygen that is capable of tumor destruction. However, recent advances in the field of nanoscience have seen the emergence of noble metal nanostructures with unique photophysical properties, well suited for applications in cancer phototherapy. Noble metal nanoparticles, on account of the phenomenon of surface plasmon resonance, possess strongly enhanced visible and near-infrared light absorption, several orders of magnitude more intense compared to conventional laser phototherapy agents. The use of plasmonic nanoparticles as highly enhanced photoabsorbing agents has thus introduced a much more selective and efficient cancer therapy strategy, viz. plasmonic photothermal therapy (PPTT). The synthetic tunability of the optothermal properties and the bio-targeting abilities of the plasmonic gold nanostructures make the PPTT method furthermore promising. In this review, we discuss the development of the PPTT method with special emphasis on the recent in vitro and in vivo success using gold nanospheres coupled with visible lasers and gold nanorods and silica-gold nanoshells coupled with near-infrared lasers.},
	keywords = {display},
	isbn = {0268-8921},
	doi = {10.1007/s10103-007-0470-x},
	author = {Huang, Xiaohua and Jain, Prashant K and El Sayed, I.H. and El-Sayed, Mostafa A.}
}
@article {1126,
	title = {Surface plasmon coupling and its universal size scaling in metal nanostructures of complex geometry: Elongated particle pairs and nanosphere trimers},
	journal = {Journal of Physical Chemistry C},
	volume = {112},
	number = {13},
	year = {2008},
	note = {Jain, Prashant K. El-Sayed, Mostafa A.},
	month = {Apr},
	pages = {4954-4960},
	abstract = {Recently, we showed that the plasmon resonance coupling between two interacting metal nanoparticles decays with the interparticle separation (in units of particle size) with the same universal trend independent of particle size or shape, metal type, or medium. This universal scaling behavior has been shown to apply to lithographically fabricated nanoparticle pairs, the metal nanoshell, plasmonic dielectric sensors, and the plasmon ruler useful in determining intersite distances in biological systems. In this article, we use electrodynamic simulations to examine the general applicability of this universal scaling behavior to more complex nanostructure geometries, for example, head-to-tail dimers of elongated particles of different aspect ratios and curvatures and a trimer of nanospheres. We find that the plasmon coupling between two elongated nanoparticles interacting head-to-tail decays according to the same universal law if the interparticle separation is scaled by the particle long-axis dimension. The absolute plasmon coupling strength, however, depends on the particle shape (i.e., aspect ratio and curvature), without affecting the universal scaling behavior. We also show that universal scaling is valid in a system of three interacting nanospheres, a first step toward extending this model to chains/arrays/assemblies of metal nanoparticles.},
	isbn = {1932-7447},
	doi = {10.1021/jp7120356},
	author = {Jain, Prashant K and El-Sayed, Mostafa A}
}
@article {1139,
	title = {Au nanoparticles target cancer},
	journal = {Nano Today},
	volume = {2},
	number = {1},
	year = {2007},
	note = {Jain, Prashant K. El-Sayed, Ivan H. El-Sayed, Mostafa A.},
	month = {Feb},
	pages = {18-29},
	abstract = {Nanoparticles with unique optical properties, facile surface chemistry, and appropriate size scale are generating much enthusiasm in molecular biology and medicine. Noble metal, especially Au, nanoparticles have immense potential for cancer diagnosis and therapy on account of their surface plasmon resonance (SPR) enhanced light scattering and absorption. Conjugation of Au nanoparticles to ligands specifically targeted to biomarkers on cancer cells allows molecular-specific imaging and detection of cancer. Additionally, Au nanoparticles efficiently convert the strongly absorbed light into localized heat, which can be exploited for the selective laser photothermal therapy of cancer. We discuss recent advances in the study and use of selectively targeted Au nanospheres in cancer photodiagnostics and photothermal therapy. By changing the shape or composition of Au nanoparticles, the SPR can be tuned to the near-infrared region, allowing in vivo imaging and photothermal therapy of cancer. The use of Au nanorods and silica-Au core-shell nanoparticles for in vivo cancer detection and therapy is discussed.},
	isbn = {1748-0132},
	doi = {10.1016/s1748-0132(07)70016-6},
	author = {Jain, Prashant K and El Sayed, I.H. and El-Sayed, Mostafa A}
}
@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 {1140,
	title = {Gold nanoparticles: interesting optical properties and recent applications in cancer diagnostic and therapy},
	journal = {Nanomedicine},
	volume = {2},
	number = {5},
	year = {2007},
	note = {Huang, Xiaohua Jain, Prashant K. El-Sayed, Ivan H. El-Sayed, Mostafa A.},
	month = {Oct},
	pages = {681-693},
	abstract = {Recent years have seen tremendous progress in the design and study of nanomaterials geared towards biological and biomedical applications, most notable among these being the noble metal nanoparticles. In this review, we outline the surface-plasmon resonance-enhanced optical properties of colloidal gold nanoparticles directed towards recent biomedical applications with an emphasis on cancer diagnostics and therapeutics. Methods of molecular-specific diagnostics/detection of cancer, including strongly enhanced surface plasmon resonance light-scattering, surface-enhanced emission of gold nanorods and surf ace-enhanced Raman scattering, are described. We also discuss the plasmonic photothermal therapy of cancer achieved by using the strongly enhanced surface-plasmon resonance absorption of gold nanospheres and nanorods.},
	isbn = {1743-5889},
	doi = {10.2217/17435889.2.5.681},
	author = {Huang, Xiaohua and Jain, Prashant K and El Sayed, I.H. and El-Sayed, Mostafa A}
}
@article {815,
	title = {Review of some interesting surface plasmon resonance-enhanced properties of noble metal nanoparticles and their applications to biosystems},
	journal = {Plasmonics},
	volume = {2},
	year = {2007},
	pages = {107-118},
	publisher = {Springer},
	abstract = {Noble metal, especially gold (Au) and silver (Ag) nanoparticles exhibit unique and tunable optical properties on account of their surface plasmon resonance (SPR). In this review, we discuss the SPR-enhanced optical properties of noble metal nanoparticles, with an emphasis on the recent advances in the utility of these plasmonic properties in molecular-specific imaging and sensing, photo-diagnostics, and selective photothermal therapy. The strongly enhanced SPR scattering from Au nanoparticles makes them useful as bright optical tags for molecular-specific biological imaging and detection using simple dark-field optical microscopy. On the other hand, the SPR absorption of the nanoparticles has allowed their use in the selective laser photothermal therapy of cancer. We also discuss the sensitivity of the nanoparticle SPR frequency to the local medium dielectric constant, which has been successfully exploited for the optical sensing of chemical and biological analytes. Plasmon coupling between metal nanoparticle pairs is also discussed, which forms the basis for nanoparticle assembly-based biodiagnostics and the plasmon ruler for dynamic measurement of nanoscale distances in biological systems.},
	isbn = {1557-1955},
	doi = {10.1007/s11468-007-9031-1},
	url = {http://dx.doi.org/10.1007/s11468-007-9031-1},
	author = {Jain, Prashant K and Huang, Xiaohua and El Sayed, I.H. and El-Sayed, Mostafa A}
}
@article {813,
	title = {Surface Plasmon Resonance Sensitivity of Metal Nanostructures:  Physical Basis and Universal Scaling in Metal Nanoshells},
	journal = {The Journal of Physical Chemistry C},
	volume = {111},
	year = {2007},
	note = {doi: 10.1021/jp0773177},
	month = {2007},
	pages = {17451 - 17454},
	publisher = {American Chemical Society},
	abstract = {In this letter, we show using extended Mie theory simulations that the sensitivity of the surface plasmon resonance (SPR) of a dielectric core-metal nanoshell increases near-exponentially as the ratio of the shell thickness-to-core radius is decreased. The plasmon sensitivity thus shows the same universal scaling behavior established recently for plasmon coupling in metal nanoshells and that in metal nanoparticle pairs. From these observations, we propose that the sensitivity is determined by the ease of surface polarization of the electrons in the nanostructure by the light. This can be used as a generalized physical principle for designing plasmonic nanostructures for effective SPR chemical and biological sensing.In this letter, we show using extended Mie theory simulations that the sensitivity of the surface plasmon resonance (SPR) of a dielectric core-metal nanoshell increases near-exponentially as the ratio of the shell thickness-to-core radius is decreased. The plasmon sensitivity thus shows the same universal scaling behavior established recently for plasmon coupling in metal nanoshells and that in metal nanoparticle pairs. From these observations, we propose that the sensitivity is determined by the ease of surface polarization of the electrons in the nanostructure by the light. This can be used as a generalized physical principle for designing plasmonic nanostructures for effective SPR chemical and biological sensing.},
	isbn = {1932-7447},
	doi = {10.1021/jp0773177},
	url = {http://dx.doi.org/10.1021/jp0773177},
	author = {Jain, Prashant K and El-Sayed, Mostafa A}
}
@article {1137,
	title = {On the universal scaling behavior of the distance decay of plasmon coupling in metal nanoparticle pairs: A plasmon ruler equation},
	journal = {Nano Letters},
	volume = {7},
	number = {7},
	year = {2007},
	note = {Jain, Prashant K. Huang, Wenyu El-Sayed, Mostafa A.},
	month = {Jul},
	pages = {2080-2088},
	abstract = {Localized surface plasmon resonances (LSPR) in lithographically fabricated gold (Au) nanodisc pairs are investigated using microabsorption spectroscopy and electrodynamic simulations. In agreement with previous work, we find that the fractional plasmon wavelength shift for polarization along the interparticle axis decays nearly exponentially with the interparticle gap. In addition, we find that the decay length is roughly about 0.2 in units of the particle size for different nanoparticle size, shape, metal type, or medium dielectric constant. The near-exponential distance decay and the interesting "universal" scaling behavior of interparticle plasmon coupling can be qualitatively explained on the basis of a dipolar-coupling model as being due to the interplay of two factors: the direct dependence of the single-particle polarizability on the cubic power of the particle dimension and the decay of the plasmonic near-field as the cubic power of the inverse distance. Using this universal scaling behavior, we are able to derive a "plasmon ruler equation" that estimates the interparticle separation between Au nanospheres in a biological system from the observed fractional shift of the plasmon band. We find good agreement of the interparticle separations estimated using this equation with the experimental observations of Reinhard et al.},
	isbn = {1530-6984},
	doi = {10.1021/nl071008a},
	author = {Jain, Prashant K and Huang, Wenyu and El-Sayed, Mostafa A}
}
@article {1138,
	title = {Universal scaling of plasmon coupling in metal nanostructures: Extension from particle pairs to nanoshells},
	journal = {Nano Letters},
	volume = {7},
	number = {9},
	year = {2007},
	note = {Jain, Prashant K. El-Sayed, Mostafa A.},
	month = {Sep},
	pages = {2854-2858},
	abstract = {It has been recently shown that the strength of plasmon coupling between a pair of plasmonic metal nanoparticles falls as a function of the interparticle gap scaled by the particle size with a near-exponential decay trend that is universally independent of nanoparticle size, shape, metal type, or medium dielectric constant. In this letter, we extend this universal scaling behavior to the dielectric core-metal shell nanostructure. By using extended Mie theory simulations of silica core-metal nanoshells, we show that when the shift of the nanoshell plasmon resonance wavelength scaled by the solid nanosphere resonance wavelength is plotted against the shell thickness scaled by the core radius, nanoshells with different dimensions (radii) exhibit the same near-exponential decay. Thus, the nanoshell system becomes physically analogous to the particle-pair system, i.e., the nanoshell plasmon resonance results from the coupling of the inner shell surface (cavity) and the outer shell surface (sphere) plasmons over a separation distance essentially given by the metal shell thickness, which is consistent with the plasmon hybridization model of Prodan, Halas, and Nordlander. By using the universal scaling behavior in the nanoshell system, we propose a simple expression for predicting the dipolar plasmon resonance of a silica-gold nanoshell of given dimensions.},
	isbn = {1530-6984},
	doi = {10.1021/nl071496m},
	author = {Jain, Prashant K and El-Sayed, Mostafa A}
}
@article {1150,
	title = {Calculated absorption and scattering properties of gold nanoparticles of different size, shape, and composition: Applications in biological imaging and biomedicine},
	journal = {Journal of Physical Chemistry B},
	volume = {110},
	number = {14},
	year = {2006},
	note = {Jain, PK Lee, KS El-Sayed, IH El-Sayed, MA},
	month = {Apr},
	pages = {7238-7248},
	abstract = {The selection of nanoparticles for achieving efficient contrast for biological and cell imaging applications, as well as for photothermal therapeutic applications, is based on the optical properties of the nanoparticles. We use Mie theory and discrete dipole approximation method to calculate absorption and scattering efficiencies and optical resonance wavelengths for three commonly used classes of nanoparticles: gold nanospheres, silica-gold nanoshells, and gold nanorods. The calculated spectra clearly reflect the well-known dependence of nanoparticle optical properties viz. the resonance wavelength, the extinction cross-section, and the ratio of scattering to absorption, on the nanoparticle dimensions. A systematic quantitative study of the various trends is presented. By increasing the size of gold nanospheres from 20 to 80 nm, the magnitude of extinction as well as the relative contribution of scattering to the extinction rapidly increases. Gold nanospheres in the size range commonly employed (similar to 40 nm) show an absorption cross-section 5 orders higher than conventional absorbing dyes, while the magnitude of light scattering by 80-nm gold nanospheres is 5 orders higher than the light emission from strongly fluorescing dyes. The variation in the plasmon wavelength maximum of nanospheres, i.e., from similar to 520 to 550 nm, is however too limited to be useful for in vivo applications. Gold nanoshells are found to have optical cross-sections comparable to and even higher than the nanospheres. Additionally, their optical resonances lie favorably in the near-infrared region. The resonance wavelength can be rapidly increased by either increasing the total nanoshell size or increasing the ratio of the core-to-shell radius. The total extinction of nanoshells shows a linear dependence on their total size, however, it is independent of the core/shell radius ratio. The relative scattering contribution to the extinction can be rapidly increased by increasing the nanoshell size or decreasing the ratio of the core/shell radius. Gold nanorods show optical cross-sections comparable to nanospheres and nanoshells, however, at much smaller effective size. Their optical resonance can be linearly tuned across the near-infrared region by changing either the effective size or the aspect ratio of the nanorods. The total extinction as well as the relative scattering contribution increases rapidly with the effective size, however, they are independent of the aspect ratio. To compare the effectiveness of nanoparticles of different sizes for real biomedical applications, size-normalized optical cross-sections or per micron coefficients are calculated. Gold nanorods show per micron absorption and scattering coefficients that are an order of magnitude higher than those for nanoshells and nanospheres. While nanorods with a higher aspect ratio along, with a smaller effective radius are the best photoabsorbing nanoparticles, the highest scattering contrast for imaging applications is obtained from nanorods of high aspect ratio with a larger effective radius.},
	isbn = {1520-6106},
	doi = {10.1021/jp057170o},
	author = {Jain, Prashant K and Lee, K. S. and El Sayed, I.H. and El-Sayed, Mostafa A}
}
@article {1152,
	title = {Determination of the minimum temperature required for selective photothermal destruction of cancer cells with the use of immunotargeted gold nanoparticles},
	journal = {Photochemistry and Photobiology},
	volume = {82},
	number = {2},
	year = {2006},
	note = {Huang, XH Jain, PK El-Sayed, IH El-Sayed, MA},
	month = {Mar-Apr},
	pages = {412-417},
	abstract = {Laser photothermal therapy of cancer with the use of gold nanoparticles immunotargeted to molecular markers on the cell surface has been shown to be an effective modality to selectively kill cancer cells at much lower laser powers than those needed for healthy cells. To elucidate the minimum light dosimetry required to induce cell death, photothermal destruction of two cancerous cell lines and a noncancerous cell line treated with antiepidermal growth factor receptor (anti-EGFR) anti body-conjugated gold nanoparticles is studied, and a numerical heat transport model is used to estimate the local temperature rise within the cells as a result of the laser heating of the gold nanoparticles. It is found that cell samples with higher nanoparticle loading require a lower incident laser power to achieve a certain temperature rise. Numerically estimated temperatures of 70-80 degrees C achieved by heating the gold particles agree well with the measured threshold temperature for destruction of the cell lines by oven heating and those measured in an earlier nanoshell method. Specific binding of anti-EGFR antibody to cancerous cells overexpressing EGFR selectively increases the gold nanoparticle loading within cancerous cells, thus allowing the cancerous cells to be destroyed at lower laser power thresholds than needed for the noncancerous cells. In addition, photothermal therapy using gold nanoparticles requires lower laser power thresholds than therapies using conventional dyes due to the much higher absorption coefficient of the gold nanoparticles.},
	isbn = {0031-8655},
	doi = {10.1562/2005-12-14-ra-754},
	author = {Huang, Xiaohua and Jain, Prashant K and El Sayed, I.H. and El-Sayed, Mostafa A}
}
@article {1151,
	title = {Plasmon coupling in nanorod assemblies: Optical absorption, discrete dipole approximation simulation, and exciton-coupling model},
	journal = {Journal of Physical Chemistry B},
	volume = {110},
	number = {37},
	year = {2006},
	note = {Jain, Prashant K. Eustis, Susie El-Sayed, Mostafa A.},
	month = {Sep},
	pages = {18243-18253},
	abstract = {The shape anisotropy of nanorods gives rise to two distinct orientational modes by which nanorods can be assembled, i.e., end-to-end and side-by-side, analogous to the well-known H and J aggregation in organic chromophores. Optical absorption spectra of gold nanorods have earlier been observed to show a red-shift of the longitudinal plasmon band for the end-to-end linkage of nanorods, resulting from the plasmon coupling between neighboring nanoparticles, similar to the assembly of gold nanospheres. We observe, however, that side-by-side linkage of nanorods in solution shows a blue-shift of the longitudinal plasmon band and a red-shift of the transverse plasmon band. Optical spectra calculated using the discrete dipole approximation method were used to simulate plasmon coupling in assembled nanorod dimers. The longitudinal plasmon band is found to shift to lower energies for end-to-end assembly, but a shift to higher energies is found for the side-by-side orientation, in agreement with the optical absorption experiments. The strength of plasmon coupling was seen to increase with decreasing internanorod distance and an increase in the number of interacting nanorods. For both side-by-side and end-to-end assemblies, the strength of the longitudinal plasmon coupling increases with increasing nanorod aspect ratio as a result of the increasing dipole moment of the longitudinal plasmon. For both the side-by-side and end-to-end orientation, the simulation of a dimer of nanorods having dissimilar aspect ratios showed a longitudinal plasmon resonance with both a blue-shifted and a red-shifted component, as a result of symmetry breaking. A similar result is observed for a pair of similar aspect ratio nanorods assembled in a nonparallel orientation. The internanorod plasmon coupling scheme concluded from the experimental results and simulations is found to be qualitatively consistent with the molecular exciton coupling theory, which has been used to describe the optical spectra of H and J aggregates of organic molecules. The coupled nanorod plasmons are also suggested to be electromagnetic analogues of molecular orbitals. Investigation of the plasmon coupling in assembled nanorods is important for the characterization of optical excitations and plasmon propagation in these nanostructures. The surface plasmon resonance shift resulting from nanorod assembly also offers a promising alternative for analyte-sensing assays.},
	isbn = {1520-6106},
	doi = {10.1021/jp063879z},
	author = {Jain, Prashant K and Eustis, Susie and El-Sayed, Mostafa A}
}
@article {1148,
	title = {Ultrafast cooling of photoexcited electrons in gold nanoparticle-thiolated DNA conjugates involves the dissociation of the gold-thiol bond},
	journal = {Journal of the American Chemical Society},
	volume = {128},
	number = {7},
	year = {2006},
	note = {Jain, PK Qian, W El-Sayed, MA},
	month = {Feb},
	pages = {2426-2433},
	abstract = {Using UV-visible extinction spectroscopy and femtosecond pump-probe transient absorption spectroscopy, we have studied the effect of femtosecond laser heating on gold nanoparticles attached to DNA ligands via thiol groups. It is found that femtosecond pulse excitation of the DNA-modified nanoparticles at a wavelength of 400 nm leads to desorption of the thiolated DNA strands from the nanoparticle surface by the dissociation of the gold-sulfur bond. The laser-initiated gold-sulfur bond-breaking process is a new pathway for nonradiative relaxation of the optically excited electrons within the DNA-modified gold nanoparticles, as manifested by a faster decay rate of the excited electronic distribution at progressively higher laser pulse energies. The experimental results favor a bond dissociation mechanism involving the coupling between the photoexcited electrons of the nanoparticles and the gold-sulfur bond vibrations over one involving the conventional phonon-phonon thermal heating processes. The latter processes have been observed previously by our group to be effective in the selective photothermal destruction of cancer cells bound to anti-epidermal growth factor receptor-conjugated gold nanoparticles.},
	isbn = {0002-7863},
	doi = {10.1021/ja056769z},
	author = {Jain, Prashant K and Qian, Wei and El-Sayed, Mostafa A}
}
@article {1149,
	title = {Ultrafast electron relaxation dynamics in coupled metal nanoparticles in aggregates},
	journal = {Journal of Physical Chemistry B},
	volume = {110},
	number = {1},
	year = {2006},
	note = {Jain, PK Qian, W El-Sayed, MA},
	month = {Jan},
	pages = {136-142},
	abstract = {We report the effect of aggregation in gold nanoparticles on their ultrafast electron-phonon relaxation dynamics measured by femtosecond transient absorption pump-probe spectroscopy. UV-visible extinction and transient absorption of the solution-stable aggregates of gold nanoparticles show a broad absorption in the 550-700-nm region in addition to the isolated gold nanoparticle plasmon resonance. This broad red-shifted absorption can be attributed to contributions from gold nanoparticle aggregates with different sizes and/or different fractal structures. The electron-phonon relaxation, reflected as a fast decay component of the transient bleach, is found to depend on the probe wavelength, suggesting that each wavelength interrogates one particular subset of the aggregates. As the probe wavelength is changed from 520 to 635 nm across the broad aggregate absorption, the rate of electron-phonon relaxation increases. The observed trend in the hot electron lifetimes can be explained on the basis of an increased overlap of the electron oscillation frequency with the phonon spectrum and enhanced interfacial electron scattering, with increasing extent of aggregation. The experimental results strongly suggest the presence of intercolloid electronic coupling within the nanoparticle aggregates, besides the well-known dipolar plasmon coupling.},
	isbn = {1520-6106},
	doi = {10.1021/jp055562p},
	author = {Jain, Prashant K and Qian, Wei and El-Sayed, Mostafa A}
}
@article {1258,
	title = {Photofragment translational spectroscopy of CH2I2 at 304 nm: Polarization dependence and energy partitioning},
	journal = {Bulletin of the Korean Chemical Society},
	volume = {18},
	number = {12},
	year = {1997},
	note = {Jung, KW Ahmadi, TS El-Sayed, MA},
	month = {Dec},
	pages = {1274-1280},
	abstract = {The photodissociation dynamics of CH2I2 has been studied at 304 nm by state-selective photofragment translational spectroscopy. Velocity distributions, anisotropy parameters, and relative quantum yields are obtained for the ground I(P-2(3/2)) and spin-orbit excited state I*(P-2(1/2)) iodine atoms, which are produced from photodissociation of CH2I2 at this wavelength. These processes are found to occur via B-1 <-- A(1) type electronic transitions. The quantum yield of I*(P-2(1/2)) is determined to be 0.25, indicating that the formation of ground state iodine is clearly the favored dissociation channel in the 304 nm wavelength region. From the angular distribution of dissociation products, the anisotropy parameters are determined to be beta(I)=0.4 for the I(P-2(3/2)) and beta (I*)=0.55 for the I*(P-2(1/2)) which substantially differ from the limiting value of 1.13. The positive values of anisotropy parameter, however, show that the primary processes for I and I* formation channels proceed dominantly via a transition which is parallel to I-I axis. The above results are interpreted in terms of dual path formation of iodine atoms from two different excited states, i.e., a direct and an indirect dissociation via curve crossing between these states. The translational energy distributions of recoil fragments reveal that a large fraction of the available energy goes into the internal excitation of the CH2I photofragment; <E-int>/E-avl=0.80 and 0.82 for the I and I* formation channels, respectively. The quantitative analysis for the energy partitioning of available energy into the photofragments is used to compare the experimental results with the prediction of direct impulsive model for photodissociation dynamics.},
	isbn = {0253-2964},
	author = {Jung, Kwang-Woo and Ahmadi, Temer S. and El-Sayed, Mostafa A}
}
@article {1290,
	title = {Photofragment Translational Spectroscopy of ICl at 304 nm},
	journal = {The Journal of Physical Chemistry A},
	volume = {101},
	year = {1997},
	note = {doi: 10.1021/jp970837p},
	month = {1997},
	pages = {6562 - 6567},
	publisher = {American Chemical Society},
	abstract = {The photodissociation dynamics of ICl is studied at 304 nm by state-selective photofragment translational spectroscopy. Velocity distributions, anisotropy parameters, and relative quantum yields are obtained for the ground I(2P3/2) and spin?orbit excited state I*(2P1/2) iodine atoms, which are produced from photodissociation of ICl at this wavelength. Two sharp velocity distributions are observed for the I channel, suggesting the existence of two dissociation pathways that correlate with ground state iodine formation. Based on the expected translational energy release and the energy separation between those peaks, the two distributions are assigned to dissociation of ICl to I(2P3/2) + Cl(2P3/2) and to I(2P3/2) + Cl*(2P1/2); the former channel appears at higher translational energy. The distribution of I* also shows two strong peaks, indicating that there are two dominant channels for the formation of I* atoms at this wavelength which we assign to the dissociation of ICl forming I*(2P1/2) + Cl(2P3/2) and I*(2P1/2) + Cl*(2P1/2), respectively. The quantum yield of I*(2P1/2) is determined to be 0.30, indicating that the formation of ground state iodine is clearly the favored dissociation channel at 304 nm. The observed anisotropy in the angular distribution of dissociation products (?) indicates that the I* + Cl and I* + Cl* channels are formed predominantly from the parallel transition (? = 1.7 for both channels) while the I + Cl and I + Cl* products are formed mainly from perpendicular transitions (? = ?0.5). The decrease in the anisotropy parameter of the I formation channels from their limiting value of ?1 is attributed to the presence of more than one path for the formation of I + Cl/Cl* photoproducts with opposite polarization for their absorbing transitions. The possible excited state dynamics, which give the observed results, are discussed in terms of the previously proposed energy correlation diagram for ICl.The photodissociation dynamics of ICl is studied at 304 nm by state-selective photofragment translational spectroscopy. Velocity distributions, anisotropy parameters, and relative quantum yields are obtained for the ground I(2P3/2) and spin?orbit excited state I*(2P1/2) iodine atoms, which are produced from photodissociation of ICl at this wavelength. Two sharp velocity distributions are observed for the I channel, suggesting the existence of two dissociation pathways that correlate with ground state iodine formation. Based on the expected translational energy release and the energy separation between those peaks, the two distributions are assigned to dissociation of ICl to I(2P3/2) + Cl(2P3/2) and to I(2P3/2) + Cl*(2P1/2); the former channel appears at higher translational energy. The distribution of I* also shows two strong peaks, indicating that there are two dominant channels for the formation of I* atoms at this wavelength which we assign to the dissociation of ICl forming I*(2P1/2) + Cl(2P3/2) and I*(2P1/2) + Cl*(2P1/2), respectively. The quantum yield of I*(2P1/2) is determined to be 0.30, indicating that the formation of ground state iodine is clearly the favored dissociation channel at 304 nm. The observed anisotropy in the angular distribution of dissociation products (?) indicates that the I* + Cl and I* + Cl* channels are formed predominantly from the parallel transition (? = 1.7 for both channels) while the I + Cl and I + Cl* products are formed mainly from perpendicular transitions (? = ?0.5). The decrease in the anisotropy parameter of the I formation channels from their limiting value of ?1 is attributed to the presence of more than one path for the formation of I + Cl/Cl* photoproducts with opposite polarization for their absorbing transitions. The possible excited state dynamics, which give the observed results, are discussed in terms of the previously proposed energy correlation diagram for ICl.},
	isbn = {1089-5639},
	doi = {doi: 10.1021/jp970837p},
	url = {http://dx.doi.org/10.1021/jp970837p},
	author = {Jung, Kwang-Woo and Ahmadi, Temer S. and El-Sayed, Mostafa A}
}
@article {875,
	title = {Fluorine Substitution Effects on the Photodissociation Dynamics of Iodobenzene at 304 nm},
	journal = {The Journal of Physical Chemistry },
	volume = {100},
	year = {1996},
	note = {doi: 10.1021/jp952662u},
	month = {1996},
	pages = {7989 - 7996},
	publisher = {American Chemical Society},
	abstract = {The photodissociation dynamics of pentafluoroiodobenzene are investigated by state-selective one-dimensional translation spectroscopy at 304 nm. We have determined the one-dimensional recoil distribution and the spatial distribution in the form of the anisotropy parameter, ?, as well as the photodissociation relative yields of both ground-state I(3P3/2) and excited-state I*(2P1/2) iodine photofragments. The results are compared to those observed for iodobenzene at 304 nm. As in iodobenzene, two velocity distributions were observed for the dissociation channel which gives ground-state iodine:? a sharp, high recoil velocity peak assigned previously to n,σ* excitation and a slow recoil velocity distribution peak assigned previously to π,π* excitation. Unlike in C6H5I, the I* distribution is relatively strong and its spatial anisotropy can be measured. The fluorine perturbation has led to a number of different observations that can be summarized as follows:? (1) The high velocity distribution has a lower average value and much broader width, suggesting more rapid energy redistribution to the fluorinated phenyl ring prior to and during the dissociation process, resulting from stronger coupling between the n,σ* and π,π* states and/or a longer excited-state lifetime; (2) the slow distribution is weaker and has an almost isotropic spatial distribution (the anisotropy parameter ? ≈ 1.0), while in the iodobenzene spectrum ? is correlated with the recoil velocity; (3) the I* quantum yield for C6F5I is 14 times larger than that for iodobenzene; and (4) ? is correlated with the velocity in the I* spectrum found for C6F5I which is not observed for iodobenzene. These observed fluorine perturbations are attributed to an increased mixing between the charge-transfer state (resulting from electron transfer from the iodine nonbonding electrons to the π* orbitals of the fluorinated benzene ring) and both the n,σ* and the ring π,π* states. This leads to two effects:? (1) a decrease in the nonbonding electron density on the iodine, which decreases the spin-orbit interaction between the n,σ* states themselves, resulting in a decrease in the curve-crossing probability (thus increasing the I* yield) and (2) an increase in the coupling between the repulsive n,σ* states and the fluorinated phenyl π,π* states, leading to an increase in the rate of energy redistribution.The photodissociation dynamics of pentafluoroiodobenzene are investigated by state-selective one-dimensional translation spectroscopy at 304 nm. We have determined the one-dimensional recoil distribution and the spatial distribution in the form of the anisotropy parameter, ?, as well as the photodissociation relative yields of both ground-state I(3P3/2) and excited-state I*(2P1/2) iodine photofragments. The results are compared to those observed for iodobenzene at 304 nm. As in iodobenzene, two velocity distributions were observed for the dissociation channel which gives ground-state iodine:? a sharp, high recoil velocity peak assigned previously to n,σ* excitation and a slow recoil velocity distribution peak assigned previously to π,π* excitation. Unlike in C6H5I, the I* distribution is relatively strong and its spatial anisotropy can be measured. The fluorine perturbation has led to a number of different observations that can be summarized as follows:? (1) The high velocity distribution has a lower average value and much broader width, suggesting more rapid energy redistribution to the fluorinated phenyl ring prior to and during the dissociation process, resulting from stronger coupling between the n,σ* and π,π* states and/or a longer excited-state lifetime; (2) the slow distribution is weaker and has an almost isotropic spatial distribution (the anisotropy parameter ? ≈ 1.0), while in the iodobenzene spectrum ? is correlated with the recoil velocity; (3) the I* quantum yield for C6F5I is 14 times larger than that for iodobenzene; and (4) ? is correlated with the velocity in the I* spectrum found for C6F5I which is not observed for iodobenzene. These observed fluorine perturbations are attributed to an increased mixing between the charge-transfer state (resulting from electron transfer from the iodine nonbonding electrons to the π* orbitals of the fluorinated benzene ring) and both the n,σ* and the ring π,π* states. This leads to two effects:? (1) a decrease in the nonbonding electron density on the iodine, which decreases the spin-orbit interaction between the n,σ* states themselves, resulting in a decrease in the curve-crossing probability (thus increasing the I* yield) and (2) an increase in the coupling between the repulsive n,σ* states and the fluorinated phenyl π,π* states, leading to an increase in the rate of energy redistribution.},
	isbn = {0022-3654},
	url = {http://dx.doi.org/10.1021/jp952662u},
	author = {Griffiths, Jennifer A. and Jung, Kwang-Woo and El-Sayed, Mostafa A}
}
@article {1288,
	title = {Photofragment translational spectroscopy of Ibr at 304 nm:  Polarization dependence and dissociation dynamics},
	journal = {Journal of Chemical Physics},
	volume = {103},
	number = {16},
	year = {1995},
	note = {Times Cited: 11},
	month = {Oct 22},
	pages = {6999-7005},
	abstract = {The photodissociation dynamics of IBr has been studied at 304 nm by state-selective photofragment translational spectroscopy. Velocity distributions, anisotropy parameters, and relative quantum yields are obtained for the ground I(P-2(3/2)) and spin-orbit excited state I*(P-2(1/2)) iodine atoms, which are produced from photodissociation of IBr at this wavelength. Two sharp velocity distributions observed for the I channel suggest the two dissociation pathways that correlate with ground-state iodine formation. Based on the expected translational energy release and the energy separation between the peaks, the two distributions have been assigned to dissociation of IBr to form I(P-2(3/2))+Br(P-2(3/2)) and I(P-2(3/2))+Br*(P-2(1/2)) with the former channel appearing at higher translational energy. The I* distribution shows one strong peak indicating that there is one dominant channel for formation of I* atoms at this wavelength which has been assigned to dissociation of IBr to form I*(P-2(1/2))+Br(P-2(3/2)) with a quantum yield of 0.1. The I* signal formed from the I*(P-2(1/2))+Br*(P-2(1/2)) dissociation channel is observed very weakly. The observed anisotropy parameter indicates that the I+Br* product (beta=-0.7) is formed mainly from the perpendicular (1) Pi(1)(2341)<--X transition while the I*+Br channel (beta=1.8) is formed predominantly from the parallel 3 Pi(0+)(2341)<--X transition followed by curve crossing to the (3) Sigma(0+)(-)(2422) State. The recoil energy dependence of the anisotropy parameter in the I atom produced in the I+Br channel shows a positive beta value above maximum of the peak recoil energy and a negative value below the peak maximum of the recoil energy distribution. These results are interpreted in terms of the presence of more than one path for the formation of I+Br photoproduct with opposite polarization for their absorbing transitions, most likely the (3) Pi(0+)(2341)<--X and the (3) Pi(1)(2341)<--X transitions. The possible excited state dynamics which give the observed results are discussed in terms of the previously proposed potential energy diagrams for IBr and ICl. (C) 1995 American Institute of Physics.},
	isbn = {0021-9606},
	doi = {10.1063/1.470326},
	author = {Jung, Kwang-Woo and Griffiths, Jennifer A. and El-Sayed, Mostafa A}
}
