Abstract

A unique split-type photoelectrochemical (PEC) immunoassay has been constructed for detection of low-abundance biocompounds (lysozyme, Lyz, used in this case) via a new trigger strategy by disintegrating bioconjugates of dopamine-grafted silica nanospheres (DA@SiO2NSs) for signal amplification. The preferred electron donor assembly of DA@SiO2NSs is first used as a molecular printboard for positioning anti-Lyz secondary antibody (Ab2) through an amide reaction. With specific immunoreactions in a high-binding microplate, a sandwich immunoassay, the DA@SiO2NSs-based bioconjugate is achieved. By initiating the disintegration of the bioconjugates via acid etching, numerous electron donors of DA are released, thus efficiently triggering hole-trapping with amplified signals obtained. The smart integration of ZnIn2S4-based heterojunctions as photoactive material, a split-type detection mode, and a new trigger strategy by disintegrating the DA@SiO2NSs-based bioconjugate offer an attractive high-throughput signal-on PEC immunoassay for detection of Lyz. Such an unusual PEC sensor exhibits an outstanding linear response to the concentration in the range between 0.002 and 500 ng mL-1, and the detection limit is as low as 0.6 ppt ( S/ N = 3). The as-fabricated assay is cost-effective and sensitive. It has been successfully used for measuring Lyz in real samples, which demonstrates great promise for practical applications.