title: Plasmonic AuNP/g-C3N4 Nanohybrid-based Photoelectrochemical Sensing Platform for Ultrasensitive Monitoring of Polynucleotide Kinase Activity Accompanying DNAzyme-Catalyzed Precipitation Amplification.
abstract: 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.
authors.forename: Junyang
authors.initials: J
authors.lastname: Zhuang
authors.forename: Wenqiang
authors.initials: W
authors.lastname: Lai
authors.forename: Mingdi
authors.initials: M
authors.lastname: Xu
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhou
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation; D002384:Catalysis; D003217:Conductometry / Q000295:instrumentation*; D021881:DNA, Catalytic / Q000737:chemistry*; D004789:Enzyme Activation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006046:Gold / Q000737:chemistry*; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D009570:Nitriles / Q000737:chemistry; D021141:Nucleic Acid Amplification Techniques / Q000295:instrumentation; D010777:Photochemistry / Q000295:instrumentation; D011116:Polynucleotide 5'-Hydroxyl-Kinase / Q000032:analysis / Q000737:chemistry*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*
chemical_list: D021881:DNA, Catalytic; D009570:Nitriles; C011206:cyanogen; D006046:Gold; D011116:Polynucleotide 5'-Hydroxyl-Kinase
keywords: T4 polynucleotide kinase; gold-decorated g-C3N4 nanosheets; isothermal amplification; photoelectrochemistry; surface plasmon resonance