Compact surface plasmon resonance (SPR) immunosensor using multichannel for simultaneous detection of small molecule compounds

A compact, portable SPR immunosensor designed for on site analysis of low-molecular-weight compounds by immunosensing is developed in the dimensions of 16 cm × 9 cm × 6 cm with four sensing microchannels. Highly sensitive and selective analysis of benzo[a]pyrene and 2-hydroxybiphenyl is realized by using an indirect competitive immunoreaction based on surface plasmon resonance (SPR) detection. A multi-microchannel flow-cell module employed here provides referencing channels to compensate bulk refractive index changes and temperature variations. It has been successfully used for simultaneous detection of the two compounds and for improvement of baseline stability by using the reference channels. Sensitivity of the compact, portable SPR sensor to ppb levels of the two compounds was equivalent to that obtained with a conventional SPR apparatus.