Department of Physics, GC University Faisalabad Sub Campus Sahiwal, Punjab, Pakistan.
Department of Physics and Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad 45650, Pakistan.
Nanotechnology. 2020 Dec 11;31(50):505501. doi: 10.1088/1361-6528/abb431.
We report a non-enzymatic facile method for the detection of L-cysteine (L-Cyst) using free-standing TiO nanotube (TNT) array-modified glassy carbon electrodes (GCEs). Self-organized, highly ordered, and vertically oriented TNT arrays were fabricated by anodization of titanium sheets in ethylene glycol-based electrolyte. Detailed electrochemical measurements were performed and it was found that modified GCE exhibited high current compared to the pristine counterpart. The high current of the modified electrode was attributed to the high surface area and enhanced electrocatalytic activities of the TNTs toward the L-Cyst oxidation. Under the optimum conditions, the modified electrode exhibited a high sensitivity of ∼1.68 µA mM cm with a low detection limit of ∼0.1 mM. The fabricated electrode was found to be sensitive to pH and electrolyte temperature. The real sample analysis of the proposed method showed a decent recovery toward L-Cyst addition in human blood serum. Furthermore, the density-funcational theory (DFT) analysis revealed that TNTs have greater affinity toward L-Cyst, having stronger binding distance after its adsorption. The higher negative E values suggested a stable and chemisorption nature. The density of states results show that the E of TNTs is significantly reduced after L-Cyst adsorption. The modified GCE showed excellent selectivity, enhanced stability, and fast response, which make TNTs a promising candidate for the enzyme-free detection of other biological analytes.
我们报告了一种非酶简便方法，用于使用独立式 TiO 纳米管 (TNT) 阵列修饰的玻碳电极 (GCE) 检测 L-半胱氨酸 (L-Cyst)。通过在乙二醇基电解液中对钛片进行阳极氧化，制备了自组织的、高度有序的和垂直取向的 TNT 阵列。进行了详细的电化学测量，结果发现修饰后的 GCE 的电流比原始电极高。修饰电极的高电流归因于 TNTs 对 L-Cyst 氧化的高表面积和增强的电催化活性。在最佳条件下，修饰电极对 L-Cyst 的氧化具有高灵敏度（约为 1.68 µA mM cm）和低检测限（约为 0.1 mM）。发现所制备的电极对 pH 和电解质温度敏感。对该方法的实际样品分析表明，在人血清中添加 L-Cyst 后具有良好的回收率。此外，密度泛函理论 (DFT) 分析表明，TNTs 对 L-Cyst 具有更大的亲和力，在吸附后具有更强的结合距离。更高的负 E 值表明其具有稳定的化学吸附性质。态密度结果表明，TNTs 的 E 值在 L-Cyst 吸附后显著降低。修饰后的 GCE 表现出优异的选择性、增强的稳定性和快速响应，这使得 TNTs 成为无酶检测其他生物分析物的有前途的候选物。
