Cu-mediated NIR photoinduced polymerization for highly sensitive electrochemical nucleic acid detection

An original electrochemical biosensor via Cu-mediated near-infrared light (NIR) polymerization was reported for highly sensitive nucleic acid detection. Lung cancer DNA as nucleic acid model was specifically recognized via phosphate-free peptide nucleic acid (PNA). Subsequently, initiators of polymerization were attached to PNA/DNA heteroduplex under the assistance of phosphate-Zr4+-carboxylate. Cu2(OH)PO4 and H2O2 system was triggered off under the irradiation of NIR light, and then hydroxyl radicals (•OH) were produced. At the same time, carbon-based radicals were also generated through the reaction between •OH and methacrylic monomers of polymerization, which initiated the photoinduced polymerization. Then, numerous ferrocene-based methacrylic monomers were modified on the surface of electrode. The limit of detection was improved to 2.6 fM with linear range from 0.01 pM to 1000 pM (R2 = 0.993), and the minimum molar number of lung cancer DNA was 26 zmol (in 10 μL). This biosensor also presented portable and cost-efficient feature due to simple operation and ubiquitous light, and no phototoxicity and good tissue penetration of NIR also endowed this strategy great potential in biological detection.