Silvered conical-bottom 96-well plates: enhanced low volume detection and the metal-enhanced fluorescence volume/ratio effect

Many diagnostic fluorescence assays are limited by sensitivity (signal/noise) and minimum sample volume requirements. Herein we report a new, silvered conical-bottom 96-well plate platform used to increase the detectability from very small volumes of micromolar concentrations of fluorophores. This technology employs the principles of metal-enhanced fluorescence (MEF), which is the process by which fluorescence emission is amplified in the near-field of plasmonic nanoparticles. By combining the MEF effect with the advantages of a small volume conical well, we report and characterize detectable emission from fluorescent solutions down to 3 microliters in volume. We report enhancement factors for fluorescein and Rhodamine 6G and correlate these factors to the synchronous scattering spectra of the silvered conical wells. Subsequently, we determine corrected enhancement factors and discuss enhancement in terms of the MEF volume ratio effect and per mole of enhanced fluorophore. The research reported herein sets the foundation for future development of even more powerful MEF-based diagnostic assays.