Near-Infrared Fluorescence Enhancement Using Silver Island Films

Abstract

Near-infrared (near-IR) excitation produces little background signal from biological molecules, making near- IR fluorescence technology highly useful in proteomic and genomic applications. To increase the emissions of near-IR fluorophores, we examined the use of metal-enhanced fluorescence on these longer wavelength dyes. IRDye ® 700- and IRDye ® 800-labeled DNA oligonucleotides and pro- teins were spotted onto silver island film (SIF)-coated glass slides, and analyzed using a LI-COR Odyssey ® IR imaging system. We observed more than 18-fold enhancement of the IRDye ® 700 and 15-fold enhancement of the IRDye ® 800- labeled DNA oligonucleotides when spotted on SIF-coated surfaces compared with uncoated surfaces. We also dem- onstrated that the enhanced emissions produced on the SIF- coated slides remained linear over several orders of magnitude, that the emissions remained reproducible across a slide surface, and that the SIF-coated slide remained effective at enhancing emissions after 9 months of storage. Our results indicate that SIF-coated glass slides are effective at enhancing near-IR fluorescence and could be developed into an effective tool to aid in molecular biological applications.