Complex F枚rster Energy Transfer Interactions between Semiconductor Quantum Dots and a Redox-Active Osmium Assembly
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- 作者：Michael H. Stewart ; Alan L. Huston ; Amy M. Scott ; Alexander L. Efros ; Joseph S. Melinger ; Kelly Boeneman Gemmill ; Scott A. Trammell ; Juan B. Blanco-Canosa ; Philip E. Dawson ; Igor L. Medintz
- 刊名：ACS Nano
- 出版年：2012
- 出版时间：June 26, 2012
- 年：2012
- 卷：6
- 期：6
- 页码：5330-5347
- 全文大小：913K
- 年卷期：v.6,no.6(June 26, 2012)
- ISSN：1936-086X
文摘
The ability of luminescent semiconductor quantum dots (QDs) to engage in diverse energy transfer processes with organic dyes, light-harvesting proteins, metal complexes, and redox-active labels continues to stimulate interest in developing them for biosensing and light-harvesting applications. Within biosensing configurations, changes in the rate of energy transfer between the QD and the proximal donor, or acceptor, based upon some external (biological) event form the principle basis for signal transduction. However, designing QD sensors to function optimally is predicated on a full understanding of all relevant energy transfer mechanisms. In this report, we examine energy transfer between a range of CdSe鈥揨nS core鈥搒hell QDs and a redox-active osmium(II) polypyridyl complex. To facilitate this, the Os complex was synthesized as a reactive isothiocyanate and used to label a hexahistidine-terminated peptide. The Os-labeled peptide was ratiometrically self-assembled to the QDs via metal affinity coordination, bringing the Os complex into close proximity of the nanocrystal surface. QDs displaying different emission maxima were assembled with increasing ratios of Os鈥損eptide complex and subjected to detailed steady-state, ultrafast transient absorption, and luminescence lifetime decay analyses. Although the possibility exists for charge transfer quenching interactions, we find that the QD donors engage in relatively efficient F枚rster resonance energy transfer with the Os complex acceptor despite relatively low overall spectral overlap. These results are in contrast to other similar QD donor鈥搑edox-active acceptor systems with similar separation distances, but displaying far higher spectral overlap, where charge transfer processes were reported to be the dominant QD quenching mechanism.