TY - JOUR T1 - Tailoring Plasmonic and Electrostatic Field Effects To Maximize Solar Energy Conversion by Bacteriorhodopsin, the Other Natural Photosynthetic System JF - Nano Letters Y1 - 2011 A1 - Yen, C. W. A1 - Hayden, S. C. A1 - Dreaden, Erik A1 - Szymanski, P. A1 - El-Sayed, Mostafa A AB - 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. VL - 11 SN - 1530-6984 N1 - Yen, Chun-Wan Hayden, Steven C. Dreaden, Erik C. Szymanski, Paul El-Sayed, Mostafa A. M3 - 10.1021/nl2018959 ER - TY - JOUR T1 - Tamoxifen-Poly(ethylene glycol)-Thiol Gold Nanoparticle Conjugates: Enhanced Potency and Selective Delivery for Breast Cancer Treatment JF - Bioconjugate Chemistry Y1 - 2009 A1 - Dreaden, Erik A1 - Mwakwari, S. C. A1 - Sodji, Q. H. A1 - Oyelere, A. K. A1 - El-Sayed, Mostafa A AB - The breast cancer treatment drug tamoxifen has been widely administered for more than three decades. This small molecule competes with 17 beta-estradiol for binding to estrogen receptor, a hormone receptor upregulated in a majority of breast cancers, Subsequently initiating programmed cell death. We have synthesized a thiol-PEoylated tamoxifen derivative that can be used to selectively target and deliver plasmonic gold nanoparticles to estrogen receptor positive breast cancer cells with tip to 2.7-fold enhanced drug potency in vitro. Optical microscopy/spectroscopy, tirne-dependent dose-response data, and estrogen competition studies indicate that augmented activity is due to increased rates of intracellular tamoxifen transport by nanoparticle endocytosis, rather than by passive diffusion of the free drug. Both ligand- and receptor-dependent intracellular delivery of gold nanoparticles suggest that plasma membrane localized estrogen receptor alpha may facilitate selective uptake and retention of this and other therapeutic nanoparticle conjugates. Combined targeting selectivity and enhanced potency provides opportunities for both multimodal endocrine treatment strategies and adjunctive laser photothermal therapy. VL - 20 SN - 1043-1802 N1 - Dreaden, Erik C. Mwakwari, Sandra C. Sodji, Quaovi H. Oyelere, Adegboyega K. El-Sayed, Mostafa A. M3 - 10.1021/bc9002212 ER -