Time-gated fluorescence measurement (TGFM) utilizing long-lived fluorescence probes is an important biosensing and imaging technology. In TGFM, following pulsed excitation, sample autofluorescence fades out within tens of nanoseconds, however the probes can continue emitting fluorescence up to milli-seconds. Thus TGFM can achieve a high signal/background ratio. In TGFM, bright probes possessing both low-energy (visible light) excitation and long lifetimes up to milli-seconds luminescent are highly desired, because such optical features can significantly simplify optical and electronic design in time-gated instruments (e.g., adopting non-UV grade optics or low-speed electronics), lower the instrument complexity and cost, and facilitate broader applications of TGFM including point-of-care testing. Conventional luminescent metal complex probes are popular for TGFM but only are able to achieve either low-energy excitation or long lifetimes in milli-seconds.<br/>In our work, in order to overcome the shortcomings of metal complex probes, we developed Mn doped I(II)-III-VI nanocrystals (NCs) to achieve all desired optical features through investigating how the optical properties (fluorescence/absorption spectra, brightness, and lifetimes) of the Mn doped NCs are affected by different host NCs, Mn concentrations in host NCs, and ZnS shelling approaches. With optimal synthetic conditions, a library of Mn doped NCs were achieved possessing high brightness, low-energy (405 nm visible light) excitation, and long lifetimes up to milli-seconds. Additionally, we developed compact TGFM instruments with high sensitivity and cost-effectiveness for these NC-based probes as signal reporters. We applied the NC probes and the instruments for sensitive detection of copper(II) ions in highly autofluorescent rum (alcoholic beverage) in a fluorescence quenching assay and also for the sensitive detection of infectious pathogen <i>Burkholderia pseudomallei</i> in a sandwich immunoassay. Our new technology should have potential to not only convert many non-time-gated fluorescence assays to time-gated assays for higher sensitivities, but also facilitate the development of highly sensitive assays for in-field testing.

Bright, low-energy excitable and fluorescence-long-lived Mn-doped I(II)-III-VI nanocrystals for time-gated fluorescence measurement

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.