Pandey P C, Upadhyay B C
Department of Applied Chemistry, Institute of Technology, Banaras Hindu University, Varanasi 221 005, India.
Talanta. 2005 Oct 31;67(5):997-1006. doi: 10.1016/j.talanta.2005.04.030. Epub 2005 May 31.
We report herein the preparation of few chemically sensitized organically modified sol-gel glass (ormosil) films and sensing of dopamine at the surface of the modified electrodes derived from these films. The chemical sensitization in ormosil-modified electrodes is introduced by incorporating: (a) potassium ferricyanide and (b) either Nafion, or dibenzo-18-crown-6 or in situ generated Prussian blue from potassium ferricyanide. Electrochemical sensing of dopamine on the surfaces of these modified electrodes have been investigated and found that: (i) the presence of dibenzo-18-crown-6 facilitate the magnitude of dopamine sensing, (ii) conversion of potassium ferricyanide into Prussian blue also enhances the magnitude of dopamine sensing as compared to that of control and Nafion sensitized modified electrodes, (iii) both dibenzo-18-crown-6 and Nafion sensitized ormosil-modified electrodes are found selective to dopamine in the presence of ascorbic acid present under physiological concentration range. These finding again directed our attention to investigate the sensing of dopamine: (a) on dibenzo-18-crown-6 incorporated within Prussian blue sensitized modified electrode and (b) in the presence of varying concentrations of dibenzo-18-crown-6 in the Prussian blue modified electrodes. The investigations made on these lines again suggested the following: (1) increase in dibenzo-18-crown-6 concentrations in the modified electrode increases the magnitude of dopamine sensing upto an optimum concentration of macrocycle; (2) the detection limit of dopamine sensing goes down to 30nM as compared to that of dibenzo-18-crown-6 incorporated with potassium ferricyanide which was found to the order of 100nM. Investigations of the interference of ascorbic acid revealed that the presence of dibenzo-18-crown-6 introduces selectivity in dopamine sensing in the presence such common interfering analyte like ascorbic acid.
我们在此报告了几种化学敏化的有机改性溶胶 - 凝胶玻璃（有机硅）薄膜的制备，以及源自这些薄膜的修饰电极表面对多巴胺的传感。通过掺入以下物质在有机硅修饰电极中引入化学敏化：（a）铁氰化钾，以及（b）Nafion、二苯并 - 18 - 冠 - 6或由铁氰化钾原位生成的普鲁士蓝。已对这些修饰电极表面上多巴胺的电化学传感进行了研究，并发现：（i）二苯并 - 18 - 冠 - 6的存在促进了多巴胺传感的幅度；（ii）与对照和Nafion敏化修饰电极相比，铁氰化钾转化为普鲁士蓝也增强了多巴胺传感的幅度；（iii）在生理浓度范围内存在抗坏血酸的情况下，发现二苯并 - 18 - 冠 - 6和Nafion敏化的有机硅修饰电极对多巴胺具有选择性。这些发现再次引导我们关注对多巴胺的传感研究：（a）在普鲁士蓝敏化修饰电极中掺入的二苯并 - 18 - 冠 - 6上，以及（b）在普鲁士蓝修饰电极中存在不同浓度二苯并 - 18 - 冠 - 6的情况下。基于这些方面的研究再次表明如下：（1）修饰电极中二苯并 - 18 - 冠 - 6浓度的增加会使多巴胺传感幅度增加，直至大环的最佳浓度；（2）与掺入铁氰化钾的二苯并 - 18 - 冠 - 6相比，多巴胺传感的检测限降至30 nM，而掺入铁氰化钾的二苯并 - 18 - 冠 - 6的检测限约为100 nM。抗坏血酸干扰的研究表明，在存在抗坏血酸这种常见干扰分析物的情况下，二苯并 - 18 - 冠 - 6的存在在多巴胺传感中引入了选择性。
