DNAzyme-controlled plasmonic coupling for SERS-based determination of Salmonella typhimurium using hybridization chain reaction self-assembled G-quadruplex

A facile and rapid SERS strategy for S. typhimurium detection based on hybridization chain reaction (HCR) self-assembled G-quadruplex DNAzyme (GQH DNAzyme)-controlled plasmonic coupling was developed. GQH DNAzyme is introduced as a biocatalyst to catalyze the oxidation of L-cysteines to cysteines (thiols to disulfides) to assist SERS signal transduction. This is the first time that the self-assembled split GQH DNAzyme-controlled plasmonic coupling is integrated with SERS sensing. The results reveal the proposed SERS strategy can quantify S. typhimurium with a wide linear range (5 to 10(5) cfu mL(-1)) and a low detection limit (4 cfu mL(-1); n= 5, mean +/- standard deviation) and RSD of 7%. The method exhibited preeminent detection performance in spiked samples with recoveries of 93.1-117%. The proposed strategy has great potential for being a versatile SERS platform for detecting a wide spectrum of analytes by replacing them with the corresponding recognition elements. Therefore, this study not only creates a practical platform for pathogenic bacteria identification and related food safety testing and environmental monitoring, but also provides a new paradigm for building SERS sensor.

Automated summary

A facile and rapid SERS strategy for S. typhimurium detection based on hybridization chain reaction (HCR) self-assembled G-quadruplex DNAzyme (GQH DNAzyme)-controlled plasmonic coupling was developed. The proposed SERS strategy can quantify S. typhimurium with a wide linear range and a low detection limit, and exhibited preeminent detection performance in spiked samples.