基于CoOOH纳米片氧化酶活性的比率荧光传感器检测抗坏血酸

研究建立一种基于羟基氧化钴纳米片（CoOOH）类氧化酶活性的比率荧光传感器，可快速、灵敏、准确地测定抗坏血酸（Ascorbic acid，AA）。在氢氧化钠溶液中，以氯化钴为原料、次氯酸钠为氧化剂，在超声条件下制备具有类氧化酶活性的CoOOH纳米片，并采用透射电子显微镜（TEM）、紫外可见吸收光谱（UV-vis）、X射线衍射（XRD）和傅里叶红外光谱（FT-IR），对所合成的材料表面形貌、光吸收特性、结晶度以及表面基团进行表征，并通过对照试验对所合成的CoOOH纳米片构建比率荧光传感器的可行性进行验证。以检测体系中CoOOH纳米片浓度及孵育时间为单因素，优化检测AA的最佳条件，并建立相应的标准曲线。结果表明，CoOOH纳米片呈典型的纳米级六边形片状，其他表征结果也与以往报道的相符。CoOOH纳米片最佳工作浓度为39.1 μmol/L，最佳孵育时间为25 min。在最优条件下，428 nm处的荧光强度（F₄₂₈）与568 nm处荧光强度（F₅₆₈）比值F₄₂₈/F₅₆₈与AA浓度在0.5~10.0 μmol/L范围内呈现良好的线性关系，线性方程为y=0.79416x+0.37917（R2=0.9965），检测限303 nmol/L（RSN=3）。将其应用于果汁饮料样品检测，回收率在88.0%~115.9%之间，且检测结果与国家标准方法的检测结果相符。以上结果表明该传感器对检测AA有较好的选择性和准确度，为AA的快速检测提供一种新思路。

Development of a Ratiometric Fluorescence Sensor for Ascorbic Acid Based on Oxidase-mimicking Activity of CoOOH Nanoflake

This work aimed at developing a ratiometric fluorescence sensor for sensitive and accurate detection of ascorbic acid (AA) based on oxidase-mimicking activity of CoOOH nanoflake. CoOOH nanoflake with oxidase-like activity was prepared by using CoCl₂ as precursor, NaClO as oxidant through a sonication method. The as-synthesized CoOOH nanoflake was characterized by transmission electron microscopy (TEM), UV–vis absorption, X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectra. Control experiments were used to demonstrate the feasibility for constructing the radiometric fluorescent sensor using the as-synthesized CoOOH nanoflake. Single-factor experiments were conducted to optimized the optimal concentration of CoOOH nanoflake and incubation time for AA detection. The results showed that the as-synthesized CoOOH nanoflakes exhibited typical hexagonal plate shape, and other characterization results also were consistent with those in previous works. The optimal concentration of CoOOH nanoflake was 39.1 μmol/L, and the optimal incubation time was 25 min. Under the optimal conditions, it was found that F₄₂₈/F₅₆₈ linearly correlated with AA concentration from 0.5 to 10.0 μmol/L with correlation coefficients of 0.9965. The regression equation was y=0.79416x+0.37917 (R2=0.9965) with a limit of detection of 303 nmol/L (RSN=3). The recoveries from fruit juice beverage samples spiked with varying concentrations of AA were in the range of 88.0%~115.9%, and analytical results of the sensor were correlated well with those of national standard method of China. These results indicated that the ratiometric fluorescent sensor had excellent selectivity and accuracy for AA detection, creating a new avenue for rapid detection of AA.