Fluorescence-positioned hybridization chain reaction system for sensitive detection of Salmonella in milk
In this study, a fluorescence-positioned hybridization chain reaction (HCR) system for the detection of single-stranded DNA (ssDNA) specific to Salmonella was developed. Target ssDNA captured by magnetic beads was used to trigger the HCR, forming multiple double-stranded DNA (dsDNA). SYBR Green Ⅰ was applied to intercalate with the minor groove of the dsDNA forming MBs+dsDNA+SYBR Green I. Magnetic separation was used to isolate the MBs+dsDNA +SYBR Green I from the excess reagents before recording the fluorescence intensity (FI). This fluorescence-positioned HCR method for the quantitative detection of Salmonella showed a limit of detection (LOD) as low as 4.2 × 10e1 CFU/mL in 0.01 M phosphate-buffered saline (PBS). When the method was applied in spiked milk samples, the LOD was recorded at 4.2 × 10e2 CFU/mL. The fluorescence-positioned HCR method provided a modification-free and fluorescence-positioned strategy for sensitive detection of target DNA which holds promise for sensitive and selective bacteria detection.