An aptamer and flower-shaped AuPtRh nanoenzyme-based colorimetric biosensor for the detection of profenofos

In this work, a simple, sensitive and selective colorimetric method was established for the detection of profenofos. Firstly, novel flower-shaped AuPtRh trimetallic nanospheres were synthesized via a simple one-pot method, and had outstanding peroxidase catalytic activity. AuPtRh nanospheres with a great specific surface area were linked with an aptamer via Au-S and Pt-S bonds to specifically recognize profenofos. A graphene oxide grafted stainless-steel mesh (SSM-GO) was prepared to be a carrier and the aptamer-AuPtRh was nonspecifically adsorbed on the surface of SSM-GO, which was to be the capture probe for the detection of profenofos in real samples. They were characterized and confirmed by transmission electron microscopy, atomic force microscopy, etc. Through the investigation of the catalytic performance on the basis of the Michaelis equation, the V_max of AuPtRh nanospheres was 22.27 × 10^-8 M s^-1, and K_m was 0.6632 mM, which indicated that the affinity of AuPtRh nanospheres was relatively higher than that of horseradish peroxidase and Au NPs. In the presence of profenofos, the aptamer-AuPtRh would specifically combine with profenofos, which would further detach from SSM-GO. Then, it was introduced into the 3,3',5,5'-tetramethylbenzidine/H₂O₂ (TMB/H₂O₂) system to form blue oxTMB. The linear range of this colorimetric biosensor was 1-300 ng L^-1 and the limit of detection was 0.725 ng L^-1. It also had good recovery and anti-interference ability in real samples, which provided a new strategy for the rapid detection of pesticides.