International Joint Research Center for Photoresponsive Molecules and Materials, Key Laboratory of Synthetic and Biological Colloids (Ministry of Education), School of Chemical and Material Engineering, Jiangnan University, Wuxi, 214122, China.
International Joint Research Center for Photoresponsive Molecules and Materials, Key Laboratory of Synthetic and Biological Colloids (Ministry of Education), School of Chemical and Material Engineering, Jiangnan University, Wuxi, 214122, China.
Biosens Bioelectron. 2019 Oct 1;142:111572. doi: 10.1016/j.bios.2019.111572. Epub 2019 Aug 3.
We propose herein an immobilization-free, split-mode cathodic photoelectrochemical (PEC) strategy coupled with a cascaded amplification for versatile biosensing. Taking DNA and microRNA (miRNA) as the model targets, the hybridization between the targets and the hairpin probe triggers the digestion of the probe DNA by T7 exonuclease (T7 Exo), thus to generate G-quadruplex (G4) forming sequences, and then the released targets (DNA or miRNA) initiate the subsequent cycling processes and generate a large amount of G4 forming sequences. Subsequently, the formed G4 sequences associate with hemin to form the G4/hemin DNAzyme, which catalytically produces 1,4-bezoquinone (BQ) for conjugating onto the surface of the chitosan (CS) deposited BiOI/ITO photocathode via the quinone-chitosan conjugation chemistry (QCCC). Under photo excitation, the covalently attached quinones can act as electron acceptors of bismuth oxyiodine (BiOI), promoting the photocurrent generation and thus allowing the elegant and "signal-on" mode for probing targets of interest. Highly sensitive and selective PEC bioassays are readily realized, with the detection limits down to 2.2 fM (for DNA) and 0.2 fM (for miRNA). Since no labeling and no electrode modification processes are needed, this split-mode PEC biosensing strategy is amenable to convenient, time/labor saving, and high-throughput detections. More significantly, it provides a novel concept to design immobilization-free and label-free cathodic PEC biosensing systems, and showcases promise in general and versatile bioanalysis research.
我们提出了一种无固定化、分裂模式的阴极光电化学（PEC）策略，与级联放大相结合，用于多功能生物传感。以 DNA 和 microRNA（miRNA）为模型靶标，靶标与发夹探针的杂交触发探针 DNA 被 T7 外切酶（T7 Exo）的消化，从而产生 G-四链体（G4）形成序列，然后释放的靶标（DNA 或 miRNA）启动后续的循环过程并产生大量的 G4 形成序列。随后，形成的 G4 序列与血红素结合形成 G4/血红素 DNA 酶，该酶通过醌-壳聚糖缀合化学（QCCC）催化产生 1,4-苯醌（BQ），用于缀合到沉积在 BiOI/ITO 光电阴极上的壳聚糖（CS）表面。在光激发下，共价附着的醌可以作为铋氧碘化物（BiOI）的电子受体，促进光电流的产生，从而允许以优雅的“信号开启”模式探测感兴趣的靶标。可以实现高灵敏度和选择性的 PEC 生物分析，检测限低至 2.2 fM（DNA）和 0.2 fM（miRNA）。由于不需要标记和电极修饰过程，这种分裂模式的 PEC 生物传感策略易于实现，方便、节省时间/劳动力，并且具有高通量检测能力。更重要的是，它为设计无固定化和无标记的阴极 PEC 生物传感系统提供了一个新的概念，并在一般和多功能生物分析研究中展示了广阔的应用前景。
