Development of Time-Resolved Luminescence Measurement Instruments for Biosensing and Bioimaging - An Overview.

Time-resolved luminescence measurement (TRLM) leverages luminescent probes with long (> 100 nanoseconds) emission decay times to enable high-contrast biosensing and bioimaging. TRLM detects probe signals after a brief delay that follows pulsed excitation. This pulse-delay-detect scheme virtually eliminates excitation light scattering and nanosecond-scale emissions from sample autofluorescence to yield measurements with exceptional signal-to-background ratios. A wide array of probes with decay times ranging from tens of microseconds to several milliseconds have been developed for TRLM, including organic dyes, lanthanide complexes, Mn-doped quantum dots, persistent luminescence nanoparticles, silicon quantum dots, and others. Meanwhile, with the recent advance in light excitation sources, photo detectors and electronic devices, various time-resolved luminescence instruments using such probes for biological applications have been reported. There are several critical reviews on the progress of luminescence-long-lived probes, however, there has been lacking a review on these instruments. This review aims to (1) present the recent development and applications of such instruments for luminescence-long-lived probes, as well as the instrument development trend towards in-field or POC applications, and (2) elucidate how the complexity, cost, compactness, and performance of TRLM instruments were affected by the optical properties of luminescence-long-lived probes. We believe that this review will bring more attention to researchers about a clear comprehension of TRLM instruments and urge researchers to further advance TRLM instruments towards low-cost, compact, and high-performance instruments for broader biosensing/imaging applications.