Near-Infrared Fluorescence Enhancement Using Silver Island Films

Near-infrared (near-IR) excitation produces little background signal from biological molecules, making nearIR 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. IRDye700and IRDye800-labeled DNA oligonucleotides and proteins 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 IRDye700 and 15-fold enhancement of the IRDye800labeled DNA oligonucleotides when spotted on SIF-coated surfaces compared with uncoated surfaces. We also demonstrated that the enhanced emissions produced on the SIFcoated 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.