A novel electrochemical sensing strategy for rapid and ultrasensitive detection of Salmonella by rolling circle amplification and DNA–AuNPs probe

•This paper presented a novel sensing strategy for the rapid and ultrasensitive detection for Salmonella.•Combination of rolling circle amplification and DNA–AuNPs probe is the first time for Salmonella electrochemical detection.•The method displayed excellent sensitivity and specificity for detection of Salmonella.•The fabricated biosensor was successfully applied to detect Salmonella in milk samples.

A novel electrochemical sensing strategy was developed for ultrasensitive and rapid detection of Salmonella by combining the rolling circle amplification with DNA–AuNPs probe. The target DNA could be specifically captured by probe 1 on the sensing interface. Then the circularization mixture was added to form a typical sandwich structure. In the presence of dNTPs and phi29 DNA polymerase, the RCA was initiated to produce micrometer-long single-strand DNA. Finally, the detection probe (DNA–AuNPs) could recognize RCA product to produce enzymatic electrochemical signal. Under optimal conditions, the calibration curve of synthetic target DNA had good linearity from 10 aM to 10 pM with a detection limit of 6.76 aM (S/N = 3). The developed method had been successfully applied to detect Salmonella as low as 6 CFU mL−1 in real milk sample. This proposed strategy showed great potential for clinical diagnosis, food safety and environmental monitoring.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideA novel electrochemical sensing strategy was developed for ultrasensitive and rapid detection of Salmonella by combining the rolling circle amplification with DNA–AuNPs probe.