Microflow measurements of antibodies fluorescence using Silicon Photomultipliers

The paper presents research made using acquisition system designed and built by the authors. It consists of Silicon Photomultipliers used for fluorescence light detection, integrated circuit dedicated for Silicon Photomultipliers and FPGA board for data acquisition. Moreover, electronic part of the system is integrated with optical section i.e. semiconductor laser, optical filters, microflow structure and optical fibers. Measured substances are passed through Polydimethylsiloxane (PDMS) microflow structure with microchannel of tens of um diameter and that is where optical detection phase takes place. The substance is stimulated by laser light and its fluorescence is being detected by SiPM. Measurements with fluorescence dyes such as sodium fluoresceinate and BD Biosciences CF series indicate sensitivity of the measurement system on the level of single picogram of the dye in ml of the buffer. CF dyes are being mixed with antibodies such as ANTI-NPR in order to measure sensitivity of the system for various concentrations of the antibody. ANTI-NPR is an antibody that reacts with human natriuretic peptide, a substance that can be found in human blood short after excessive heart effort or heart failure. Measurement system is not designed only for NPR antibody but also e.g. myoglobin, troponin and others. That is why not only single antibody has been measured.