Electron Transfer-Driven Nanozymes Boost Biosensor Sensitivity via a Synergistic Signal Amplification Strategy
Zongyou Chen, Keyang Lai, Aoxue Wang, Huayuan Ji, Sha Yu, Zhipeng Fang, Daofeng Liu, Juan Peng, Weihua Lai
Abstract
The conventional gold nanoparticles (AuNPs) with insufficient brightness face substantial challenges in developing a sensitive lateral flow immunoassay (LFIA). Herein, multibranched manganese–gold (Mn–Au) nanoparticles (MnAuNPs) with a Au core–Mn shell nanostructure were synthesized by a one-pot method. The Mn shell of valence-rich and Au core of high electron transfer efficiency endowed MnAuNPs with oxidase-like activity, which oxidized 3,3′,5,5′-tetramethylbenzidine (TMB) only by electron transfer. Ox-TMB, which was the oxidation product of TMB, is an excellent photothermal agent. Furthermore, the synergistic photothermal effect of ox-TMB and MnAuNPs significantly enhanced the photothermal conversion efficiency. The synergistic photothermal effect of multibranched MnAuNPs and ox-TMB has enabled highly sensitive quantitative detection. The LFIA based on MnAuNPs (cascade LFIA) has achieved sensitive detection of Escherichia coli O157:H7. The entire detection process was completed in 25 min. The limit of detection of cascade LFIA was 239 CFU mL –1, which was 37.21-fold lower than that of AuNPs-LFIA (8892 CFU mL –1 ). The recoveries of cascade LFIA were 82.63–111.67%, with coefficients of variation of 4.28–14.19%. Overall, this work suggests the potential of MnAuNPs and ox-TMB in the development of sensitive LFIA and broadens the biosensing strategies for point-of-care testing.