The present work developed an electrochemical genosensor for the detection of virulence outer membrane protein A (ompA,tDNA) gene ofCronobacter sakazakii(C. sakazakii) by exploiting the excellent glucose-oxidase-mimicking activity of copper Metal-organic frameworks (Cu-MOF) doped with gold nanoparticle (AuNPs). The signal nanotags of signal probes (sDNA) that biofunctionalized[email protected]([email protected]) were designed using an Au-S bond. The biosensor was prepared by immobilization capture probes (cDNA) onto an electrodeposited AuNPs-modified glassy carbon electrode (GCE).[email protected]was introduced onto the surface of the GCE via a hybridization reaction between cDNA and tDNA, as well as tDNA and sDNA. Due to the enhanced oxidase-mimicking activity of[email protected]to glucose, the biosensor gave a linear range of 1.0 × 10−15to 1.0 × 10−9mol L−1to tDNA with a detection limit (LOD) of 0.42 fmol L−1under optimized conditions using differential pulse voltammetry measurement (DPV). It can be applied in the direct detection ofompAgene segments in total DNA extracts fromC. sakazakiiwith a broad linear range of 5.4−5.4 × 105CFU mL−1and a LOD of 0.35 CFU mL−1. The biosensor showed good selectivity, fabricating reproducibility and storage stability, and can be used for the detection ofompAgene segments in real samples with recovery between 87.5% and 107.3%.Keywords:electrochemical biosensor;C. sakazakii;gold-nanoparticle-doped copper Metal-organic frameworks;ompAgene;glucose-oxidase-mimicking activity
This work presented an electrochemical biosensor for the detection of virulence outer membrane protein A ( ompA ) gene of Cronobacter sakazakii ( C. sakazakii ), which was based on the mimic peroxidase activity of boron doped quantum dots-Au nanoparticles (BQDs-AuNPs) and a signal amplification strategy of exonuclease III (Exo III)-assisted target-recycling (EATR). The electrochemical signal was come from the electrochemical reduction of H 2 O 2 by BQDs-AuNPs nanozyme. Due to the enhanced peroxidase-mimic electrocatalytic efficiency of BQDs-AuNPs and the EATR strategy, the biosensor showed a broad linear range (1.0 × 10 -15 – 1.0 × 10 -8 mol L -1 ) and a low limit of detection (LOD, 4.0 × 10 -17 mol L -1 ). The constructed biosensor could also be applied in direct detection of extracted DNA from C. sakazakii . A good linear relationship (7.8 – 7.8 × 10 6 CFU mL −1 ) between the logarithm concentration of C. sakazakii and electrochemical signal was obtained with a LOD of 2.6 CFU mL −1 . The biosensor was applied in the detection of impA gene segments in contaminated infant formula with recoveries ranged in 83.4 – 108.2%.
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