Enzyme-free biosensor for ultrasensitive detection of mecA gene utilizing electrochemically controlled atom transfer radical polymerization triggered by copper nanoflowers enriched on DNA polymers.

Herein, an ultrasensitive electrochemical biosensor is constructed to detect mecA gene by utilizing electrochemically controlled atom transfer radical polymerization (eATRP) triggered by copper nanoflowers enriched on DNA polymers. Firstly, specific capture and enrichment of mecA gene is achieved by using magnetic separation system, effectively weakening the interference of the complex matrix. Next, enzyme-free hybridization chain reaction is triggered in the presence of mecA gene to form long DNA polymers containing numerous active sites for subsequent binding to streptavidin-copper hybrid nanoflowers (SA@Cu HNFs). Then, numerous Cu(I) afforded by the reduction and dissolution of collected SA@Cu HNFs, as catalysts and signal transduction modulators, are applied to promote the click reaction between azide-modified DNA probes on the electrode surfaces and propargyl 2-bromoisobutyrate. Finally, plentiful electroactive polymers are continually grown in situ via eATRP, significantly boosting the signal output. Under optimal conditions, the biosensor can detect mecA gene as low as 0.06 fM, with a linear range from 0.1 fM to 10 pM. Moreover, the biosensor is high selective, and suitable for mecA gene detection in actual environment and food samples. Due to its ultra-sensitivity and cost-effectiveness, the developed strategy can achieve other genes detection by simply substituting the recognition element of target.