P3HT-PbS nanocomposites with mimicking enzyme as bi-enhancer for ultrasensitive photocathodic biosensor

Photocathodic biosensor has great capability in anti-interference from reductive substances, however, the low signal intensity of photoactive species with inferior detection sensitivity restricts its wide application. In this work, the P3HT-PbS nanocomposites were synthesized as signal tags, by integrating with target-trigger generated hemin/G-quadruplex nanotail as bi-enhancer to significantly apmplify the photocurrent, an ultrasensitive pho- tocathodic biosensor was proposed for detection of beta 2-microglobulin (beta 2-MG) Impressively, P3HT with cathode signal is an attractive polymer consisted of substantial thiophene groups with high absorption coefficient and mobility of photo-generated holes, which could anchor with the PbS dots as sensitizer, providing a high charge mobility and strong photosensitivity. More importantly, target-trigger generated hemin/G-quadruplexes could accept the electron from illuminated photoactive species through the conversion of Fe(III)/Fe(II) in hemin, effectively reducing charge recombination rate as well as accelerating the generation of electron acceptor O-2 in the assistant of H2O2. Moreover, hemin/G-quadruplexes inherited the HRP mimicking catalytic capability that further improved the produce of plentiful O-2. As a result, PEC cathode signal was significantly enhanced for sensitive analysis of beta 2-MG protein with a good detection range of 0.1 pg/mL to 100 ng/mL. It would provide a path for establishing PEC platform with excellent anti-interference ability and extend the application of photoelectrochemical (PEC) biosensor in bioanalysis and early disease diagnosis.

Automated summary

In this study, P3HT-PbS nanocomposites and target-trigger generated hemin/G-quadruplex nanotail were integrated as dual enhancers to develop an ultrasensitive photocathodic biosensor for the detection of beta 2-microglobulin (beta 2-MG). The combination of the two enhancements significantly amplified the photocurrent, allowing for a good detection range of 0.1 pg/mL to 100 ng/mL.