Realization of a time-correlated photon counting technique for fluorescence analysis

Area of Science:

• Photonics and Spectroscopy
• Analytical Chemistry

Background:

• Accurate detection of ultralow light levels is crucial for sensitive fluorescence analysis.
• Existing methods may lack sensitivity, cost-effectiveness, or portability for certain applications.

Purpose of the Study:

• To propose and evaluate a novel time-correlated photon counter (TCPC) module for ultralow light detection in fluorescence analysis.
• To assess the performance of the TCPC in terms of photon counting accuracy, sensitivity, and dynamic range.

Main Methods:

• The TCPC utilizes a silicon photomultiplier sensor, Poisson statistics algorithm, and double time windows technique for precise photon counting.
• The instrument is compatible with time-correlated single photon counting (TCSPC) for recording faint light signal arrival times.
• The TCPC was used to analyze the intensity and lifetime of fluorescein isothiocyanate (FITC).

Main Results:

• The TCPC achieved a limit of detection of 16 pg/ml for FITC, with a wide linear dynamic range from 2.86 pg/ml to 0.5 µg/ml.
• The measured fluorescence lifetime of FITC was 3.758 ns, consistent with results from commercial instruments.
• The developed module is low-cost and compact.

Conclusions:

• The proposed time-correlated photon counter is a viable and accurate tool for ultralow light detection in fluorescence analysis.
• Its performance characteristics suggest suitability for applications like point-of-care testing.
• The instrument offers a cost-effective alternative to sophisticated commercial fluorescence analysis systems.