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

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.