Jia-Dong Zhang,Lei Lu,Xiu-Fang Zhu,Li-Jing Zhang,Shan Yun,Chuan-Song Duanmu,Lei He
In this work, we developed an innovative closed bipolar electrode (BPE)-electrochemiluminescence (ECL) sensing strategy with generality for target detection. Based on charge balance and 100% current efficiency between the closed BPE poles and the driving electrodes, one of the driving electrodes in one cell of the closed BPE system was employed as ECL sensing surface to reflect the target on the BPE pole in the opposite cell. Compared with traditional BPE-ECL sensing method, which in general adopted the anodic ECL reagents such as Ru(bpy)32+ and its coreactant on one pole (anode) to reflect the target (occurring reduction reaction) on the other pole (cathode), the difference was that the targets occurring oxidation reaction could be detected by the anodic ECL reagents based on this strategy. To verify the feasibility of this strategy, the detection principle was stated first, and Fe(CN)64– as model target at anodic BPE pole were detected by anodic ECL reagents (Ru(bpy)32+ and TprA) on the driving electrode first. The ECL signals showed good performance for target detection. By changing the size and the material of the BPE pole where the targets were located, the detection of l-ascorbic acid (AA), uric acid (UA), and dopamine (DA) as other model targets with higher detection limit were accomplished. Visual and high-throughput detection of AA, UA, and DA were also successfully realized by an array of the closed BPE system. This closed BPE (array) system is an effective supplement of traditional BPE-ECL sensing and could greatly expand the scope of the detection target.
In this study, a simple, robust, label-free electrochemical biosensor based on the ligase chain reaction (LCR) was developed for the highly sensitive and selective detection of single nucleotide polymorphisms (SNPs) using Fe(CN)63−/Fe(CN)64− as a redox indicator. High sensitivity and specificity were achieved by using the LCR, which employs a thermostable and single-base discerning Hifi Taq DNA ligase to repeatedly ligate adjacently hybridized LCR-specific probes during thermal cycles, resulting in the highly specific exponential amplification of DNA targets. The electrochemical signal of the biosensor was further decreased using stem-loop probe DNA (SL-DNA), which specifically hybridized with LCR products on the electrodes. The linear dynamic range and high sensitivity of the mutant DNA (MutDNA) and wild-type DNA (WtDNA) LCR-based electrochemical biosensors for the detection of MutDNA and WtDNA were studied in vitro, with a broad linear dynamic range of 10 aM to 10 pM and detection limits of 1.18 aM and 0.35 aM, respectively. In addition, the MutDNA and WtDNA LCR-based electrochemical biosensors were able to accurately detect allele frequency changes as low as 0.1%. In summary, the developed LCR-based electrochemical biosensor provides a useful platform to monitor SNPs in a highly sensitive and specific manner.
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