Chemistry Department, P.O. Box 94, Makhanda, 6140, South Africa.
Chemistry Department, P.O. Box 94, Makhanda, 6140, South Africa; Institute for Nanotechnology Innovation, Rhodes University, P.O. Box 94, Makhanda, 6140, South Africa.
Colloids Surf B Biointerfaces. 2020 Jun;190:110981. doi: 10.1016/j.colsurfb.2020.110981. Epub 2020 Mar 16.
The fabricating of metal oxide thin films onto conducting surfaces continues to grow and their potential applications as surfaces for biosensor applications is of paramount importance. The correct orientation of glucose oxidase redox enzymes yields very important biointerfaces capable of selectively detecting d-glucose as a measure of blood sugar for healthy and diabetic sick patients. The electrodeposition of redox enzymes, such as glucose oxidase enzymes, onto gold electrode surfaces pre-modified with nickel oxide was investigated in this work. The surface characterization confirmed the chemical nature, morphology and thin film composition of the modification of bare and modified gold electrodes. The electrodeposition of GOx enzyme onto nickel oxide/hydroxide thin film resulted in a surface with excellent bioelectrocatalytic properties towards the detection of d-glucose. The nickel within the nickel oxide/hydroxide thin film had a Ni(II) oxidation state. A well-defined redox peak of GOx enzyme co-factor (FAD/FADH) was observed confirming the oriented immobilization onto NiO/Ni(OH) conducting surfaces. The amount of GOx enzyme deposited was determined by integrating the charge (Q = 0.368 μF) under the reduction peak and the surface coverage was found to be 1.43 × 10 mol. cm. A linear plot of electrocatalytic reduction currents against d-glucose concentrations was obtained up to 30.0 mM with a linear correlation coefficient (R) of 0.99. The limit of detection (LoD) using S/N = 3 was calculated to be 1.54 ± 0.03 mM. The sensitivity of the biosensors was 1.95 ± 0.13 μA.mM.cm. The selectivity towards only d-glucose and not ascorbic acid and uric acid was evaluated and the Au-NiO/Ni(OH)-GOx could not detect 1.0 mM of ascorbic acid and uric acid.
将金属氧化物薄膜制备到导电表面上的工作仍在继续，并且它们作为生物传感器应用表面的潜在应用非常重要。正确定向葡萄糖氧化酶氧化还原酶可产生非常重要的生物界面，能够选择性地检测 d-葡萄糖，作为健康和糖尿病患者血糖的衡量标准。本工作研究了在预先用氧化镍修饰的金电极表面上电沉积氧化还原酶（如葡萄糖氧化酶）。表面特性证实了裸金和修饰金电极的化学性质、形态和薄膜组成的修饰。GOx 酶在镍氧化物/氢氧化物薄膜上的电沉积导致表面对 d-葡萄糖的检测具有极好的生物电催化性能。镍氧化物/氢氧化物薄膜中的镍具有 Ni(II)氧化态。观察到 GOx 酶辅因子（FAD/FADH）的良好定义的氧化还原峰，证实了其定向固定在 NiO/Ni(OH) 导电表面上。通过整合还原峰下的电荷量（Q = 0.368 μF）来确定沉积的 GOx 酶量，表面覆盖率为 1.43×10 mol. cm。获得了 d-葡萄糖浓度的电催化还原电流的线性图，直到 30.0 mM，线性相关系数（R）为 0.99。使用 S/N = 3 计算出的检测限（LoD）为 1.54 ± 0.03 mM。生物传感器的灵敏度为 1.95 ± 0.13 μA.mM.cm。评估了对仅 d-葡萄糖而不是抗坏血酸和尿酸的选择性，并且 Au-NiO/Ni(OH)-GOx 无法检测 1.0 mM 的抗坏血酸和尿酸。
