@article {1086,
	title = {Bacteriorhodopsin/TiO(2) nanotube arrays hybrid system for enhanced photoelectrochemical water splitting},
	journal = {Energy \& Environmental Science},
	volume = {4},
	number = {8},
	year = {2011},
	note = {Allam, Nageh K. Yen, Chun-Wan Near, Rachel D. El-Sayed, Mostafa A.},
	month = {Aug},
	pages = {2909-2914},
	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 assembly and use of a bacteriorhodopsin (bR)/TiO(2) nanotube array hybrid electrode system. Photoanode materials composed of similar to 7 mu m long self-ordered and vertically oriented nanotube array of titanium dioxide films were fabricated via the anodization of Ti foil in formamide electrolytes containing NH(4)F at room temperature followed by sensitization of the electrodes with bR. The stability of bR on the TiO(2) surface was found to depend on the pretreatment process of the TiO(2) films. Our results demonstrate the opportunity to fabricate fairly stable bR/TiO(2) hybrid electrodes that can be used as photoanodes for photoelectrochemical water splitting. Under AM 1.5 illumination (100 mW/cm(2)), the hybrid electrodes achieved a photocurrent density of 0.65 mA/cm(2) which is a similar to 50\% increase over that measured for pure TiO(2) nanotubes (0.43 mA/cm(2)) fabricated and tested under the same conditions. In the presence of a redox electrolyte, the photocurrent increased to 0.87 mA/cm(2). To the best of our knowledge, this is the first report on the use of bR/TiO(2) hybrid electrodes in photoelectrochemical water oxidation cells. We believe the proton pumping property of bR can be used in a variety of applications, especially those related to third generation photovoltaic cells.},
	isbn = {1754-5692},
	doi = {10.1039/c1ee01447a},
	author = {Allam, N. K. and Yen, C. W. and Near, R. D. and El-Sayed, Mostafa A}
}
@article {1325,
	title = {Plasmonic Imaging of Human Oral Cancer Cell Communities during Programmed Cell Death by Nuclear-Targeting Silver Nanoparticles},
	journal = {Journal of the American Chemical Society},
	volume = {133},
	number = {44},
	year = {2011},
	note = {Times Cited: 13Austin, Lauren A. Kang, Bin Yen, Chun-Wan El-Sayed, Mostafa A.},
	month = {Nov},
	pages = {17594-17597},
	abstract = {Plasmonic nanoparticles (NPs) have become a useful platform in Medicine for potential uses in disease diagnosis and treatment. Recently, it has been reported that plasmonic NPs conjugated to nuclear targeting peptides cause DNA damage and apoptotic populations in cancer cells. In the present work, we utilized the plasmonic scattering property and the ability of nuclear-targeted silver nanoparticles (NLS/RGD-AgNPs) to induce programmed cell death in order to image in real-time the behavior of human oral squamous carcinoma (HSC-3) cell communities during and after the induction of apoptosis. Plasmonic live-cell imaging revealed that HSC-3 cells behave as nonprofessional phagocytes. The induction of apoptosis in some cells led to attraction of and their subsequent engulfment by neighboring cells. Attraction to apoptotic cells resulted in clustering of the cellular community. Live-cell imaging also revealed that,. as the initial,concentration of NLS/RGD-AgNPs. increases, the rate of self killing increases and the degree of attraction and clustering decreases. These results are discussed in terms of the proposed mechanism of cells undergoing programmed cell death.},
	isbn = {0002-7863},
	doi = {10.1021/ja207807t},
	author = {Austin, Lauren and Kang, B. and Yen, C. W. and El-Sayed, M. A.}
}
@article {1074,
	title = {Tailoring Plasmonic and Electrostatic Field Effects To Maximize Solar Energy Conversion by Bacteriorhodopsin, the Other Natural Photosynthetic System},
	journal = {Nano Letters},
	volume = {11},
	number = {9},
	year = {2011},
	note = {Yen, Chun-Wan Hayden, Steven C. Dreaden, Erik C. Szymanski, Paul El-Sayed, Mostafa A.},
	month = {Sep},
	pages = {3821-3826},
	abstract = {We have explored the plasmonic field enhancement of current production from bacteriorhodopsin (bR) by maximizing the blue light effect, where the influx of blue photons absorbed by the long-lived M intermediate drastically shortens the time scale of the bR photocycle, leading to current enhancement. To this end, we used three approaches in our solution-based cell: proton selective Nafion membrane. (2) We maximized the plasmonic surface (1) We improved the charge carrier separation in solution through the use of a field effects by selecting the capping polymer with minimum surface field screening and best nanopartide stability. (3) We selected the plasmonic nanoparticle with the strongest plasmonic field whose surface plasmon resonance has the largest spectral overlap with the blue light absorbing M-intermediate. Theoretical models are used to explain experimental results, which show a 40 nm cuboidal nanoparticle capped with 55k PVP polymer to give the best photocurrent enhancement. Enhanced by this particle, bR in our Nafion membrane solution cell gave a photocurrent of 0.21 mu A/cm(3), which is 5000 times larger than the published results for thin film bR electrochemical cells even with an applied bias. Additional possible enhancements are proposed.},
	isbn = {1530-6984},
	doi = {10.1021/nl2018959},
	author = {Yen, C. W. and Hayden, S. C. and Dreaden, Erik and Szymanski, P. and El-Sayed, Mostafa A}
}
@article {1101,
	title = {Bacteriorhodopsin-based photo-electrochemical cell},
	journal = {Biosensors \& Bioelectronics},
	volume = {26},
	number = {2},
	year = {2010},
	note = {Chu, Li-Kang Yen, Chun-Wan El-Sayed, Mostafa A.},
	month = {Oct},
	pages = {620-626},
	abstract = {A simple solution-based electrochemical cell has been constructed and successfully employed in the detection of the photoelectric response upon photoexcitation of bacteriorhodopsin (bR) without external bias. Commercially-available indium tin oxide (ITO) glasses served as the optical windows and electrodes. Small amounts of bR suspensions (similar to 100 mu L) were utilized as the photovoltaic medium to generate the proton gradient between two half-cells separated by a molecular porous membrane. Continuous broadband visible light (lambda >380 nm) and a short-pulse 532-nm laser were employed for the photoexcitation of bR. Upon the modulated cw broadband irradiation, an instantaneous rise and decay of the current was observed. Our observations of the pH-dependent photocurrent are consistent with previous reports in a bR thin film configuration, which also showed a polarity inversion at pH 5-6. This is due to the change of the priority of the proton release and proton uptake in the photocycle of bR. Studies on the ionic strength effect were also carried out at different KC1 concentrations, which resulted in the acceleration of the rise and decay of the photoelectric response. This was accompanied by a decrease in the stationary photocurrent at higher KC1 concentrations in the broadband excitation experiments. The solution-based electrochemical cell uses aqueous medium, which is required for the completion of the bR proton pumping function. Due to the generation of the stationary current, it is advantageous to convert solar energy into electricity without the need of film-based photovoltaic devices with external bias. (C) 2010 Elsevier B.V. All rights reserved.},
	isbn = {0956-5663},
	doi = {10.1016/j.bios.2010.07.013},
	author = {Chu, L. K. and Yen, C. W. and El-Sayed, Mostafa A}
}
@article {1100,
	title = {On the Mechanism of the Plasmonic Field Enhancement of the Solar-to-Electric Energy Conversion by the Other Photosynthetic System in Nature (Bacteriorhodopsin): Kinetic and Spectroscopic Study},
	journal = {Journal of Physical Chemistry C},
	volume = {114},
	number = {36},
	year = {2010},
	note = {Chu, Li-Kang Yen, Chun-Wan El-Sayed, Mostafa A.},
	month = {Sep},
	pages = {15358-15363},
	abstract = {We have recently reported Ag nanoparticles (AgNPs) plasmonic field enhancement of the Bacteriorhodopsin (bR) photocurrent observed during its proton pump photocycle in solution. We proposed a mechanism based on the plasmonic field enhancement of the blue light effect which bypasses the slow part of the photocycle and increases the rate of proton production and thus the observed photocurrent. In this present work, we studied the AgNPs plasmonic field effect on the spectroscopy and kinetics of the bR proton pumping photocycle. We examined the blue light effect on both the recovery rate of bR and the decay rate of the M intermediate by using 532-nm short-pulsed laser excitation of bR in the presence of AgNPs and continuous-wave blue light exposure. Our observation showed that the recovery of bR and the decay of the M intermediate are both greatly accelerated in the presence of both AgNPs and blue light simultaneously. This gives support for the proposed mechanism of the enhanced proton current in the presence of AgNPs with a plasmon band in the blue region. It was found experimentally that the 40 nm-AgNPs enhancement of the blue light effect on the decay rate is around 400x larger than that of 8 nm-AgNPs. This is found to be in agreement with the known dependence of the plasmonic field on size and the overlap of the plasmonic extinction band with the absorption band of the M intermediates.},
	isbn = {1932-7447},
	doi = {10.1021/jp105468x},
	author = {Chu, L. K. and Yen, C. W. and El-Sayed, Mostafa A}
}
@article {1089,
	title = {Plasmonic Field Enhancement of the Bacteriorhodopsin Photocurrent during Its Proton Pump Photocycle},
	journal = {Journal of the American Chemical Society},
	volume = {132},
	number = {21},
	year = {2010},
	note = {Yen, Chun-Wan Chu, Li-Kang El-Sayed, Mostafa A.},
	month = {Jun},
	pages = {7250-+},
	abstract = {The proton pump photocycle of bacteriorhodopsin (bR) produces photocurrent on a microsecond time scale which is assigned to the deprotonation step forming the M(412) intermediate. The return of the M(412) intermediate to the bR ground state (bR(570)) has two pathways: (1) thermally via multiple intermediates (which takes 15 ms) or (2) by a more rapid and direct process by absorbing blue light (which takes hundreds of nanoseconds). By using nanoparticles (Ag, Ag-Au, and Au NPs) having different surface plasmon resonance extinction spectra, it is found that Ag NPs whose spectrum overlaps best with the M(412) absorption regions enhance the stationary photocurrent 15 times. This large enhancement is proposed to be due to the accelerated photoexcitation rate of the M(412) (in the presence of the plasmon field of the light in this region) as well as short-circuiting of the photocycle, increasing its duty cycles.},
	isbn = {0002-7863},
	doi = {10.1021/ja101301u},
	author = {Yen, C. W. and Chu, L. K. and El-Sayed, Mostafa A}
}
@article {1107,
	title = {Photocatalysis in Gold Nanocage Nanoreactors},
	journal = {Journal of Physical Chemistry A},
	volume = {113},
	number = {16},
	year = {2009},
	note = {Yen, C. W. Mahmoud, M. A. El-Sayed, M. A.},
	month = {Apr},
	pages = {4340-4345},
	abstract = {The photodegradation of methyl orange was found to take place very efficiently using hollow Au nanocages which are known to have remaining Ag on their interior walls which can be oxidized to Ag(2)O. The degradation rate is found to be more efficient than photodegradation reaction using semiconductor nanomaterials, such as TiO(2) and ZnO. The reaction rate is found to increase by increasing the degree of Ag oxidation on the interior wall of the nanocages prior to the reaction and is a function of the nanocavity size and the pore density of the nanocage walls. As the cage size varies, it is found that the photocatalytic rate increases and then decreases with a maximum rate at nanoparticle size of 75 nm with a medium pore density-in the walls. All these results suggest that the catalysis is occurring inside the cavity, whose interior walls are covered with the Ag(2)O catalysts. Similar to the mechanism proposed in the degradation by the other semiconductors, we propose that the photodegradation mechanism involves the formation of the hydroxyl radical resulting from the photoexcitation of the Ag(2)O semiconductor. The observed results on the rate are discussion in terms of (1) the surface area of the inner wall covered with Ag (Ag(2)O), (2) the density and size of the pores in the walls, and (3) the cavity size of the nanoparticles.},
	isbn = {1089-5639},
	doi = {10.1021/jp811014u},
	author = {Yen, C. W. and Mahmoud, M A and El-Sayed, Mostafa A}
}
@article {1108,
	title = {Plasmonic Field Effect on the Hexacyanoferrate (III)-Thiosulfate Electron Transfer Catalytic Reaction on Gold Nanoparticles: Electromagnetic or Thermal?},
	journal = {Journal of Physical Chemistry C},
	volume = {113},
	number = {45},
	year = {2009},
	note = {Yen, Chun-Wan El-Sayed, Mostafa A.},
	month = {Nov},
	pages = {19585-19590},
	abstract = {The rate of the catalytic reaction between hexacyanoferrate (III) and thiosulfate on gold nanoparticles is found to increase when irradiated with light in resonance with surface plasmon absorption of the gold nanoparticles. Turning on the plasmonic field by turning on light at the surface plasmon extinction band wavelength could increase the rate by one of two possible mechanisms. In the first one, the electromagnetic field could chan-e its radiative or nonradiative electron transfer process (Mechanism I). In the other mechanism (Mechanism II), the strongly absorbed light by the gold nanoparticles is rapidly converted from light energy into heat energy that increases the temperature of the medium and increases the reaction rate. In order to determine which mechanism the plasmonic catalytic effect follows, we determined the activation energy of the reaction by heating the reaction solution via two different methods: irradiation at the surface plasmon resonance of the gold catalyst and by direct heating in a thermostat. The two activation energies are found to be the same, suggesting that the plasmonic field effect in this electron transfer reaction is thermally induced.},
	isbn = {1932-7447},
	doi = {10.1021/jp905186g},
	author = {Yen, C. W. and El-Sayed, Mostafa A}
}
