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

Preparation of Zn-MOF/MWCNT-COOH/GCE Nanoelectrochemical Sensor for Rapid Determination of Anthocyanins in Food

摘要:

花青素是一种重要的功能性物质，具有抗氧化、抗衰老、调节血糖、保护肝脏、预防心血管疾病、护眼等保健功效，为了快速分析食品中花青素的含量，本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，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(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:

Anthocyanins, a class of flavonoid compounds, exhibit significant bioactive properties including anti-aging effects, glycemic control, hepatoprotective functions, prevention of cardiovascular diseases and eye protection. To rapidly detect anthocyanin content in food, a nano-electrochemical sensor (Zn-MOF/MWCNTs-COOH/GCE) was fabricated using carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) and zinc-based metal-organic frameworks (Zn-MOF) as composite modifiers. Employing cyanidin-3-O-glucoside (C3G) as the target analyte, a rapid detection method for anthocyanins in food matrices was established. The nano-electrochemical sensors were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectra (EIS). The cyclic voltammogram shows that a well-defined oxidation peak of cyanidin-3-0-glucoside (C3G) was observed, but no reduction peak was found during the electrochemical reaction on the glass carbon electrode, MWCNTs-COOH / GCE and Zn-MO F/MWCNTs-COOH / GCE sensor, which indicating that the electrochemical redox reaction is irreversible, the oxidation peak current values of C3G on glass carbon electrodes, MWCNTs-COOH / GCE, and Zn-MOF/MWCNTs-COOH / GCE sensors were 8.31, 54.41, and 71.04 μA, with a 6.5 and 8,5 times increase, respectively. Linear sweep voltammetry was then employed to optimize experimental conditions, the results as follows: citric acid buffer with pH 3.0 as the electrolyte buffer, the amounts of composite modification materials(MWCNT-COOH and Zn-MOF) was 6 μL, and the volume ratio between the two was 3:1. At these conditions, the oxidation peak current of C3G linearly increased with its concentration between 5 and 80 μmol/L, with detectable limitation of 1.9×10-7 mol/L (S/N=3). The developed method was used for the determination of anthocyanins in black rice, its results were agreed with that of the pH differential method. the recovery rate is 105.29%~110.54%, with the advantages such as easy operation, rapidity and good precision and anti-interference. Therefore, the developed method is practical to rapidly determination of anthocyanins in foods.