Visible to Near-Infrared Fluorescence Enhanced Cellular Imaging on Plasmonic Gold Chips.

Rapid and sensitive detections of a variety of surface and intracellular proteins, nucleic acids, and other cellular biomarkers are important to elucidating biological signaling pathways and to devising disease diagnostics and therapeutics. Here, sensitive imaging and detection of cellular proteins on fluorescence-enhancing, nanostructured plasmonic gold (pGold) chips is presented. Imaging of fluorescently labeled cellular biomarkers on pGold is enhanced by 2-30-fold in the visible to near infrared (NIR) range of ≈500-900 nm. The high fluorescence enhancement of >700 nm significantly improves the dynamic range and signal/background ratios of NIR imaging, allowing high-performance multicolor imaging in the visible-NIR range using high quantum yield (QY) visible dyes and lower QY NIR fluorophores. Further, multiple cellular proteins of single cells of various cell types can be detected through microarraying of cells, useful for potentially hundreds and thousands different types of cells assayed on a single chip down to small cell numbers. This work suggests a simple, high throughput, high sensitivity, and multiplexed single-cell analysis method on fluorescence enhancing plasmonic substrates in the entire visible to NIR window.