Dual-readout immunosensor constructed based on brilliant photoelectrochemical and photothermal effect of polymer dots for sensitive detection of sialic acid.

A delicate dual-readout immunosensor based on tetraphenylporphyrin-polymer dots (TPP-Pdots) with brilliant photoelectrochemical and photothermal performance was first successfully fabricated for the ultrasensitive detection of sialic acid (SA). Herein, TPP-Pdots with good biocompatibility, extraordinary light-harvesting ability and excellent photothermal conversion efficiency was used to capture SA antibody as dual-functional bioprobe for generating photocurrent and temperature signal. Furthermore, the large surface and morphology-mediated of rutile-TiO2 (R-TiO2) was beneficial to load amounts of TPP-Pdots for improved PEC signal and photothermal signal. Importantly, the temperature readout resulted from the variation of target concentration could be easily obtained by a universal thermometer which was time-saving and cost-saving. Under the optimized experimental conditions, the photocurrent densities and temperature changes proportionally increased with the increasing of SA concentrations from 3.5 × 10-5 ng/mL to 35 ng/mL (R = 0.996). Impressively, the dual-readout approach proposed here not only featured with good accuracy and high sensitivity for SA detection, but also paved the way for the development of a dual-readout immunoassay based on PEC biosensor.