Nanoscale control of Ag nanostructures for plasmonic fluorescence enhancement of near-infrared dyes
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AbstractPotential utilization of proteins for early detection and diagnosis of various diseases has drawn considerable interest in the development of protein-based detection techniques. Metal induced fluorescence enhancement offers the possibility of increasing the sensitivity of protein detection in clinical applications. We report the use of tunable plasmonic silver nanostructures for the fluorescence enhancement of a near-infrared (NIR) dye (Alexa Fluor 790). Extensive fluorescence enhancement of ∼2 orders of magnitude is obtained by the nanoscale control of the Ag nanostructure dimensions and interparticle distance. These Ag nanostructures also enhanced fluorescence from a dye with very high quantum yield (7.8 fold for Alexa Fluor 488, quantum efficiency (Qy) = 0.92). A combination of greatly enhanced excitation and an increased radiative decay rate, leading to an associated enhancement of the quantum efficiency leads to the large enhancement. These results show the potential of Ag nanostructures as metal induced fluorescence enhancement (MIFE) substrates for dyes in the NIR "biological window" as well as the visible region. Ag nanostructured arrays fabricated by colloidal lithography thus show great potential for NIR dye-based biosensing applications. [Figure not available: see fulltext.] © 2013 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.
CitationXie F, Pang JS, Centeno A, Ryan MP, Riley DJ, et al. (2013) Nanoscale control of Ag nanostructures for plasmonic fluorescence enhancement of near-infrared dyes. Nano Research 6: 496–510. Available: http://dx.doi.org/10.1007/s12274-013-0327-5.
SponsorsThis work was supported by UK EPSRC Programme Grant (EP/G060940/1). F. Xie is supported by the Imperial College JRF scheme. J. Pang acknowledges financial support by King Abdullah University of Science and Technology. We thank Dr. L. Danos for PicoQuant lifetime measurements.