Application of the silicon photomultiplier for fluorescence photobleaching measurement

In the paper a measurement method of fluorescence intensity reduction (called photobleaching) caused by excitation light was presented. Intensity of fluorescence light was measured by silicon photomultiplier (SiPM) – sensor which allows single photons detection. It has more compact dimensions and lower bias voltage in comparison to photomultiplier tube, presently used in many laboratory devices. Standard photometric cuvettes with a capacity of 1.6 ml and optical path length of 10 mm were used for the measurements. Sodium fluoresceinate dissolved in 10 mM TRIS buffer at pH 8.5 was used as the fluorescent dye. The solution was tested at a concentration of 100 μg per ml with constant excitation light from LED source over the time of measurement.