In this work, a novel surface plasmon resonance (SPR) enhanced electrochemiluminescence (ECL) biosensing model was first designed based on Au NPs@polydopamine (PDA)@CuInZnS QDs nanocomposite. Au NPs were coated with the PDA layer via the electrostatic force. CuInZnS QDs were bound on the surface of Au NPs@PDA nanocomposite. CuInZnS QDs worked as ECL luminophore in the sensing application. PDA shell not only controlled the separation length between Au NPs and QDs to induce SPR enhanced ECL response, but also limited the potential charge transfer and ECL quenching effect. As a result, the nanocomposite ECL intensity was twice that of QDs with K2S2O8. The tumor suppressor p53 gene was detected in the amplified ECL sensing system. The sensing method has a linear response in the range of 0.1 nmol/L to 15 nmol/L with a detection limit of 0.03 nmol/L. The DNA biosensor based on the nanocomposite showed excellent sensitivity, selectivity, reproducibility and stability and was applied in spiked human serum samples with satisfactory results.
Keywords: Biosensor; CuInZnS QDs; Nanocomposite; Polydopamine; Surface-enhanced ECL; p53 gene.
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