基于金属有机骨架材料Zn-MOF的纳米电化学传感器快速测定食品中的花青素

Development of a Zn-MOF/MWCNTs-COOH/GCE Electrochemical Nanosensor for Rapid Determination of Anthocyanin Content in Food

摘要:

该文以羧基化多壁碳纳米管（MWCNTs-COOH）、锌-有机骨架材料（Zn-MOF）为复合修饰材料制备了Zn-MOF/MWCNTs-COOH/GCE纳米电化学传感器，以矢车菊素-3-O-葡萄糖苷（C3G）为研究对象，并建立了一种快速检测食品中花青素的方法。采用扫描电镜技术、循环伏安法及电化学交流阻抗技术对该纳米电化学传感器进行了表征，其循环伏安图表明，C3G在玻碳电极、MWCNTs-COOH/GCE和Zn-MOF/MWCNTs-COOH/GCE传感器上电化学反应过程中均出现一个良好的氧化峰，但未发现还原峰，表明其电化学氧化还原反应是不可逆的，其氧化峰电流值分别为8.31、54.41和71.04 μA，分别增加了6.5倍和8.5倍。用线性伏安法对实验条件进行优化，结果如下：pH值为3.0的柠檬酸缓冲液为电解质缓冲液，MWCNTs-COOH和Zn-MOF的复合修饰材料的修饰量为6 μL，二者体积比为3:1。在此条件下，C3G在该传感器上的氧化峰电流响应值与其浓度在5~80 μmol•L-1的浓度之间具有良好的线性关系，最低检出限为1.9×10-7 mol•L-1 (S/N=3)，该方法用于黑米花青素的检测，其结果与pH示差法基本一致，其加标回收率为105.29%~110.54%，且具有简便快速、精度高、抗干扰性好等优点，因此该法可用于食品中花青素的快速检测。

Abstract:

To rapidly detect the anthocyanin content in food, a Zn-MOF/MWCNTs-COOH/GCE electrochemical nanosensor was fabricated using carboxylated multiwalled carbon nanotubes (MWCNTs-COOH) and zinc-based metal-organic frameworks (Zn-MOFs) as composite modifiers. By employing cyanidin-3-O-glucoside (C3G) as the target analyte, a rapid detection method for anthocyanins in food matrices was established. The nano-electrochemical sensor was characterized using scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. In the cyclic voltammogram, during the electrochemical reaction on the glassy carbon electrode (MWCNTs-COOH/GCE) and Zn-MOF/MWCNTs-COOH/GCE sensor, a well-defined oxidation peak of C3G was observed, while no reduction peak was detected, which indicates that the electrochemical redox reaction is irreversible. The oxidation peak current of C3G on the GCE was 8.31 μA, while those on the MWCNTs-COOH/GCE and Zn-MOF/MWCNTs-COOH/GCE sensor were 54.41 and 71.04 μA, representing 6.5-fold and 8.5-fold increases, respectively. Linear sweep voltammetry was then employed to determine the optimal experimental conditions: a citric acid buffer at pH 3.0 should be used as the electrolyte buffer, along with 6 μL of the composite modifiers (MWCNTs-COOH and Zn-MOF) in a 3:1 volume ratio. Under these conditions, the oxidation peak current of C3G showed an excellent linear relationship, with a concentration between 5 and 80 μmol•L-1 and a detection limit of 1.9×10-7 mol•L-1 (S/N=3). The developed method was used to determine the anthocyanin content in black rice, and the results were in good agreement with those of the pH differential method, with recoveries ranging from 105.29% to 110.54%. The method has the advantages of simple operation, rapid response, high precision, and excellent anti-interference performance, making it practical for the rapid determination of anthocyanin content in food matrices.