Signal amplification detection of DNA using a sensor fabricated by one-step covalent immobilization of amino-terminated probe DNA onto the polydopamine-modified screen-printed carbon electrode

•The SPCE functionalized with polydopamine.•One-step covalent immobilization of DNA achieved.•Signal amplification obtained by Ag deposition. An electrochemical DNA sensor was fabricated based on covalent immobilization of amino-terminated probe DNA onto the polydopamine (PDA) modified screen-printed carbon electrode (SPCE). Immobilization was achieved via one-step Schiff base reaction between the amino group of the probe DNA and quinones in PDA. PDA was formed via electrochemical polymerization of dopamine monomer on the SPCE surface. After a sandwich-type hybridization reaction, the gold nanoparticle-labeled reporter DNA was bound onto the DNA sensor surface to further induce silver deposition in the presence of silver enhancer solutions. The electrochemical stripping signal of the deposited silver nanoparticles in KCl solution was used to monitor the hybridization reaction. Signal amplification enhanced the sensitivity for target DNA detection. The proposed method could detect target DNA at a linear range from 1.0pM to 70pM, with a detection limit of 0.3pM. The DNA sensor exhibited good stability and acceptable reproducibility. The sensor also showed selectivity against non-complementary target DNA.