Platinum nanozyme-mediated temperature sensor for sensitive photothermal immunoassay of YKL-40 under near-infrared light

This work reports on the proof-of-concept of an innovative photothermal immunosensing platform for the sensitive screening of YKL-40 in biological fluids by coupling near-infrared light (NIR)-excited platinum nanoparticles (PtNPs) with a handheld digital thermometer. First, a sandwiched immunoreaction was performed on a monoclonal rabbit anti-human YKL-40 capture antibody-coated microplate using PtNP-labeled anti-YKL-40 secondary antibody. After the formation of the sandwiched immunocomplex, the carried PtNP caused the photothermal conversion under 808 nm laser irradiation relative to the 3,3 ',5,5 '-tetramethylbenzidine (TMB)-H2O2 system, thereby, resulting in an increase in the temperature of the detection solution. Under optimum conditions, the PtNP-based photothermal immunoassay exhibited a linear relationship within a dynamic range of 0.03-100 ng mL-1 at a low limit of detection of 0.014 ng mL-1 YKL-40. High specificity, good reproducibility, and long-term stability were achieved with this system. In addition, the accuracy of this method was evaluated for the analysis of human serum samples, giving well-matched results compared with the human YKL-40 enzyme-linked immunosorbent assay. This work reports a photothermal immunoassay for the sensitive screening of YKL-40 coupling near-infrared light-excited platinum nanoparticles with a handheld digital thermometer.