CdS:Mn-sensitized 2D/2D heterostructured g-C3N4-MoS2 with excellent photoelectrochemical performance for ultrasensitive immunosensing platform

Abstract

The exploration of advanced photoactive materials with fine photoelectrochemical (PEC) performance is always the hot subject in PEC bioanalysis. Herein, Mn-doped CdS nanocrystals (CdS:Mn)-sensitized 2D/2D heterostructured g-C3N4-MoS2 was prepared and served as photoactive matrix of PEC sensing platform for myoglobin (Myo) detection using CuO nanoparticles labeled anti-Myo (anti-Myo-CuO) conjugates as signal amplification tags. The heterostructured g-C3N4-MoS2 could effectively promote the electron transfer and evidently restrain the recombination of electron-hole pairs, producing the high photocurrent response. Upon loaded CdS:Mn on the heterostructured g-C3N4-MoS2 to form co-sensitized structure, the photocurrent further gives a dramatically increase. To proof the performance of the co-sensitized structure in PEC bioanalysis, a sandwich type PEC immunosensor was designed by using the co-sensitized structure as photomatrix, Myo as model protein, and anti-Myo-CuO conjugates as amplifying tags. The introduction of anti-Myo-CuO conjugates in this system could significantly quench the PEC response of the sensing interface owing to the competition of the light-generated electron, poor conductivity and steric hindrance of the anti-Myo-CuO conjugates. In virtue of synergistic amplification of the CdS:Mn sensitized heterostructured g-C3N4-MoS2 and the anti-Myo-CuO conjugates, the immunosensor could respond down to 0.42 pg mL−1 Myo with a detectable range of 1.0 pg mL−1 to 50 ng mL−1. Moreover, this PEC platform demonstrates high specificity and sensitivity for Myo detection in real biological matrices. This strategy may furnish new insights for applications of novel 2D/2D heterostructures in PEC bioanalysis.