Colorimetric-SERS dual-mode aptasensor for Staphylococcus aureus based on MnO 2 @AuNPs oxidase-like activity.

The nanozyme-linked aptamer-sorbent assay (NLASA) is a rapid way to screen and characterize aptamer binding to targets. In this paper, a MnO ₂ @AuNPs@aptamer (Apt) based NLASA coupled with colorimetric-SERS dual-mode for Staphylococcus aureus (S. aureus) detection is presented. Cu,Fe-CDs were used as the reducing agent to synthesize MnO ₂ and gold nanoparticles (AuNPs). Then, they were fabricated to obtain MnO ₂ @AuNPs with oxidase (OXD)-like and SERS activities. The S. aureus aptamer was conjugated to MnO ₂ @AuNPs and enhanced the OXD-like activity, which realized the specific capture of S. aureus in food matrices. In addition, S. aureus improves the oxidation of 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid (ABTS) but inhibits 3,3',5,5'-tetramethylbenzidine (TMB) to generate Raman-active oxTMB with MnO ₂ @AuNPs@Apt. This sensor was used for detections of S. aureus in a concentration ranged from 10 ¹ to 10 ⁷  CFU/mL with a detection limit of 0.926 CFU/mL (colorimetric) and 1.561 CFU/mL (SERS), and the recovery is 85%-105% in real samples.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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