超长α-Ag_(3)VO_(4)纳米线类氧化酶活性及传感应用研究

Insight Into the Oxidase-like Activity of Ultralongα-Ag_(3)VO_(4) Nanowire and Its Sensing Application

合成稳定高效的纳米酶代替传统天然酶是目前酶催化领域的研究热点。采用适合大规模制备的溶液共沉淀法,在常温常压下合成了一种稳定的单斜相α-Ag_(3)VO_(4)纳米线,其长度约为40μm、长径比可达80(40μm/500 nm)。同时,研究了单斜相α-Ag_(3)VO_(4)纳米线类氧化酶活性。结果表明,该纳米线具有广普的类氧化酶活性,对3,3’,5,5’-四甲基联苯胺(TMB)、邻苯二胺(OPD)、2′-联氨-双(3-乙基苯并噻唑啉-6-磺酸)(ABTS)三种底物均表现出了良好的催化活性。另外,系统研究了pH、反应时间及催化剂和底物浓度对单斜相α-Ag_(3)VO_(4)纳米线催化活性的影响。结果表明,高酸度有利于体系双电子转移过程的进行,钒酸银纳米线的类氧化酶活性与催化剂和底物浓度正相关。利用经典的酶促反应动力学方程,得到了α-Ag_(3)VO_(4)纳米线催化TMB氧化的动力学参数和基本规律。研究发现,其米氏常数(Km)为0.69 mmol·L^(-1),最大初始反应速率(V_(max))为1.8×10^(-7)mol·L^(-1)·s^(-1),纳米线可以有效吸附并活化溶液中的分子氧,真实氧化剂为超氧自由基和单线态氧。在抑制酶促反应模式下,探索了α-Ag_(3)VO_(4)+TMB体系作为传感平台定量检测生物小分子的能力,结果发现该系统对抗坏血酸具有良好的响应,检测限为6.9μmol·L^(-1)。基于钒酸银纳米线的类氧化酶活性,建立一种快速、简便、灵敏地检测抗坏血酸的比色法。

The synthesis of stable and high-performance nano enzymes to replace natural enzymes is a hot research subject in the enzyme catalytic field.In this work,the co-precipitation method suitable for largescale preparation was adopted to synthesize a stable monoclinicα-Ag_(3)VO_(4)nanowire at room temperature and pressure.The length of the nanowire was about 40μm,and the aspect ratio was up to 80(40μm/500nm).The oxidase-like activity of such monoclinicα-Ag_(3)VO_(4)nanowire was investigated.The results suggested that the nanowire had broad-spectrum oxidase-like activity and good catalytic activity toward TMB,OPD,and ABTS.The effects of pH,reaction time,catalyst,and substrate concentration on the catalytic activity were systematically studied.The results indicated that the high acidity was favorable for two-electron transfer,and the catalytic activity was positive correlation to the concentration of material and substance.The kinetic parameters and basic rules of TMB oxidation catalyzed byα-Ag_(3)VO_(4)nanowire were obtained using the enzymatic reaction’s classical kinetic equation.It was found that the Michaelis constant(K;)was0.69 mmol·L^(-1),and the maximum initial reaction rate(V_(max))is 1.8×10^(-7)mol·L^(-1)·s^(-1).The mechanism study found that the nanowires could effectively adsorb and activate molecular oxygen in the solution.The real oxidants were superoxide radical and singlet oxygen.Besides,the ability of theα-Ag_(3)VO_(4)+TMB system as a sensing platform for quantitative detection of small biological molecules under inhibitory enzymatic mode was explored.The sensing system was found to have a good response to ascorbic acid(AA)with a detection limit of 6.9μmol·L^(-1).The findings revealed potential of using oxidase-like activity ofα-Ag_(3)VO_(4)to develop a fast,simple and sensitive colorimetric sensing method for AA.