School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland.
Analyst. 2019 Aug 16;144(17):5299-5307. doi: 10.1039/c9an01085h.
Electrochemical enzymatic biosensors are the subject of research due to their potential for in vivo monitoring of glutamate, which is a key neurotransmitter whose concentration is related to healthy brain function. This study reports the use of biocompatible oxidised carbon nanohorns (o-CNH) with a high surface area, to enhance the immobilization of glutamate oxidase (GluOx) for improved biosensor performance. Two families of biosensors were designed to interact with the anionic GluOx. Family-1 consists of covalently functionalised o-CNH possessing hydrazide (HYZ) and amine (PEG-NH2) terminated surfaces and Family-2 comprised non-covalently functionalised o-CNH with different loadings of polyethyleneimine (PEI) to form a cationic hybrid. Amperometric detection of H2O2 formed by enzymatic oxidation of glutamate revealed a good performance from all designs with the most improved performance by the PEI hybrid systems. The best response was from a o-CNH : PEI ratio of 1 : 10 mg mL-1, which yielded a glutamate calibration plateau, JMAX, of 55 ± 9 μA cm-2 and sensitivity of 111 ± 34 μA mM-1 cm-2. The low KM of 0.31 ± 0.05 mM indicated the retention of the enzyme function, and a limit of detection of 0.02 ± 0.004 μM and a response time of 0.88 ± 0.13 s was determined. The results demonstrate the high sensitivity of these biosensors and their potential for future use for the detection of glutamate in vivo.
电化学酶生物传感器因其在活体监测谷氨酸方面的潜力而成为研究的主题，谷氨酸是一种关键的神经递质，其浓度与健康的大脑功能有关。本研究报告了使用具有高表面积的生物相容性氧化碳纳米角（o-CNH）来增强谷氨酸氧化酶（GluOx）的固定化，以提高生物传感器的性能。设计了两种与阴离子 GluOx 相互作用的生物传感器家族。家族-1 由共价功能化的 o-CNH 组成，具有酰肼（HYZ）和胺（PEG-NH2）末端表面，家族-2 由不同负载量的聚乙烯亚胺（PEI）组成的非共价功能化的 o-CNH 组成，形成阳离子杂化体。通过酶促氧化谷氨酸形成的过氧化氢的安培检测显示，所有设计都具有良好的性能，其中 PEI 杂化体系的性能得到了最大改善。最佳响应来自于 o-CNH：PEI 比为 1：10mg mL-1，其产生 55 ± 9 μA cm-2 的谷氨酸校准平台，JMAX 和 111 ± 34 μA mM-1 cm-2 的灵敏度。低的 KM 值为 0.31 ± 0.05 mM，表明保留了酶的功能，检测限为 0.02 ± 0.004 μM，响应时间为 0.88 ± 0.13 s。结果表明，这些生物传感器具有高灵敏度，并且有可能用于未来在体内检测谷氨酸。
