ACS Appl Mater Interfaces. 2015 Apr 22;7(15):8330-8. doi: 10.1021/acsami.5b01923. Epub 2015 Apr 9.
A convenient and feasible photoelectrochemical (PEC) sensing platform based on gold nanoparticles-decorated g-C3N4 nanosheets (AuNP/g-C3N4) was designed for highly sensitive monitoring of T4 polynucleotide kinase (PNK) activity, using DNAzyme-mediated catalytic precipitation amplification. To realize our design, the AuNP/g-C3N4 nanohybrid was initially synthesized through in situ reduction of Au(III) on the g-C3N4 nanosheets, which was utilized for the immobilization of hairpin DNA1 (HP1) on the sensing interface. Thereafter, a target-induced isothermal amplification was automatically carried out on hairpin DNA2 (HP2) in the solution phase through PNK-catalyzed 5'-phosphorylation accompanying formation of numerous trigger DNA fragments, which could induce generation of hemin/G-quadruplex-based DNAzyme on hairpin DNA1. Subsequently, the DNAzyme could catalyze the 4-chloro-1-naphthol (4-CN) oxidation to produce an insoluble precipitation on the AuNP/g-C3N4 surface, thereby resulting in the local alternation of the photocurrent. Experimental results revealed that introduction of AuNP on the g-C3N4 could cause a ∼100% increase in the photocurrent because of surface plasmon resonance-enhanced light harvesting and separation of photogenerated e-/h+ pairs. Under the optimal conditions, the percentage of photocurrent decrement (ΔI/I0, relative to background signal) increased with the increasing PNK activity in a dynamic working range from 2 to 100 mU mL(-1) with a low detection limit (LOD) of 1.0 mU mL(-1). The inhibition effect of adenosine diphosphate also received a good performance in PNK inhibitor screening research, thereby providing a useful scheme for practical use in quantitative PNK activity assay for life science and biological research.
基于金纳米粒子修饰的 g-C3N4 纳米片（AuNP/g-C3N4）的简便可行的光电化学（PEC）传感平台，通过 DNAzyme 介导的催化沉淀扩增，用于高灵敏度监测 T4 多核苷酸激酶（PNK）活性。为了实现我们的设计，首先通过 Au(III)在 g-C3N4 纳米片上的原位还原合成 AuNP/g-C3N4 纳米杂化物，用于在传感界面上固定发夹 DNA1（HP1）。此后，通过 PNK 催化的 5'-磷酸化伴随形成大量触发 DNA 片段，在溶液相中自动进行发夹 DNA2（HP2）的靶诱导等温扩增，这可以诱导发夹 DNA1 上产生基于血红素/G-四链体的 DNAzyme。随后，DNAzyme 可以催化 4-氯-1-萘酚（4-CN）氧化，在 AuNP/g-C3N4 表面产生不溶性沉淀，从而导致光电流的局部变化。实验结果表明，由于表面等离子体共振增强的光捕获和光生电子/空穴对的分离，在 g-C3N4 上引入 AuNP 会导致光电流增加约 100%。在最佳条件下，相对于背景信号的光电流减小百分比（ΔI/I0）随着 PNK 活性在 2 至 100 mU mL(-1)的动态工作范围内增加而增加，检测限（LOD）低至 1.0 mU mL(-1)。二磷酸腺苷的抑制作用也在 PNK 抑制剂筛选研究中表现良好，从而为生命科学和生物研究中定量 PNK 活性测定的实际应用提供了有用的方案。
