Host-guest mediated electrochemical MiRNA-21 sensing via nanozymes Mn-PCN-222 catalysis

In this work, a host-guest mediated electrochemical sensor for miRNA-21 via nanozymes Mn-PCN-222 catalysis was reported. In brief, the atom transfer radical polymerization (ATRP) reaction was enabled via the continuous conversion of hydrogen peroxide (H2O2) to hydroxyl radicals (HO∙) via Mn-PCN-222. Specifically, miRNA-21 was captured and immobilized on the surface of an indium tin oxide (ITO) electrode using complementary DNA (Cp-DNA). In this way, miRNA-21 provided a sequence that can hybridize with F-DNA(ferrocene modified DNA primer). At the same time, an ATRP initiator (β-CD-Br15) was attached to the electrode through host-guest interaction. The controlled polymerization of ferrocene methyl methacrylate (FcMMA) using β-CD-Br15 for continuous activator regeneration (ICAR) ATRP yields polymer FcMMAn with a high square wave voltammetry (SWV) signal in the presence of target miRNA-21. Without added miRNA-21, a lower SWV current was observed because β-CD-Br15 was not successfully modified onto the ITO electrode. The biosensor has also been used in the detection of serum samples. Moreover, the proposed host-guest mediated electrochemical biosensor has potential in bioanalytical applications for sensitive detection of biomolecules.