A novel detection strategy for nitrofuran metabolite residues: Dual-mode competitive-type electrochemical immunosensor based on polyethyleneimine reduced graphene oxide/gold nanorods nanocomposite and silica-based multifunctional immunoprobe

Excessive residues of semicarbazide (SEM) can accumulate in animals after the original drug has been abused, posing a risk to human health. Herein, based on multifunctional silica-initiated dual mode signal response, a novel competitive-type immunosensor was constructed for ultrasensitive detection of SEM. As a preliminary signal amplification platform for immunosensors, polyethyleneimine reduced graphene oxide composite gold nanorods (PEI-rGO/AuNRs) modified gold electrodes (AuE) provide a high specific surface area and high electrical conductivity. The thionine-aminated silica nanospheres-AuPt (thi-SiO2@AuPt) were synthesized by a racile coprecipitation method for enzyme immobilization and redox species loading. The multifunctional silica nanosphere conjugated with labeling antibodies (Ab2) was employed as an immunoprobe. The per unit concentration target of SEM can be determined by differential pulse voltammetry (DPV) to detect the thi loaded on the immunoprobe, which can also be determined by square wave voltammetry (SWV) to detect the current generated by the reaction system of H2O2 and hydroquinone (HQ) catalyzed by the immunoprobe with peroxidase. Under optimal conditions, the proposed immunosensor displayed a wide linear range from 1 μg-0.01 ng/mL and low detection limits (S/N = 3) of 0.488 pg/mL and 0.0157 ng/mL, respectively. Ultimately, the developed method exhibits excellent performance in practical applications, providing promising probabilities for SEM detection.