A Multi-Site initiation reversible Addition - Fragmentation Chain - Transfer electrochemical cocaine sensing

In this study, we reported a novel amplification method based on thermally mediated surface initiated reversible addition fragmentation chain transfer (SI-RAFT) and host-guest chemistry for electrochemical analysis of cocaine. Firstly, the NH2-DNA probes were fixed on the surface of the indium tin oxide (ITO) electrode by addition reaction with 1,4-phenylenediisothiocyanate (PDITC). Then the NH2-DNA could specifically recognize target cocaine, and the Ferrocene-DNA (Fc-DNA) probes was connected to the ITO electrode also by specifically binding with cocaine. Next, beta-CD-Br-15 was fixed on the surface of the ITO by host-guest interaction between Fc and beta-cyclodextrin (beta-CD). Finally, ferrocenylmethyl methacrylates (FcMMA) were grown on the surface of ITO via SI-RAFT to form polymer, and then the obtained electrode was measured by square wave voltammetry (SWV). The intensity of signal and the logarithm of cocaine concentration has a good linear relationship in the range of 0.01 ng/mL to 1 mu g/mL (R-2 = 0.9963), and the detection limit can go down to 0.003 ng/ mL (S/N = 3). Moreover, this strategy is appropriate for illegal drugs detection and possess good anti -interference ability for the detection of cocaine in serum samples.