Chemical and Biomolecular Engineering Department University of California, Los Angeles, Los Angeles, CA 90095, USA.
Analyst. 2020 Apr 7;145(7):2602-2611. doi: 10.1039/c9an01969c. Epub 2020 Jan 30.
The sensitivity and response time of glutamate sensors based on glutamate oxidase immobilized on planar platinum microelectrodes have been improved to near the theoretical performance limits predicted by a detailed mathematical model. Microprobes with an array of electroenzymatic sensing sites have emerged as useful tools for the monitoring of glutamate and other neurotransmitters in vivo; and implemented as such, they can be used to study many complex neurological diseases and disorders including Parkinson's disease and drug addiction. However, less than optimal sensitivity and response time has limited the spatiotemporal resolution of these promising research tools. A mathematical model has guided systematic improvement of an electroenzymatic glutamate microsensor constructed with a 1-2 μm-thick crosslinked glutamate oxidase layer and underlying permselective coating of polyphenylenediamine and Nafion reduced to less than 200 nm thick. These design modifications led to a nearly 6-fold improvement in sensitivity to 320 ± 20 nA μM cm at 37 °C and a ∼10-fold reduction in response time to 80 ± 10 ms. Importantly, the sensitivity and response times were attained while maintaining a low detection limit and excellent selectivity. Direct measurement of the transport properties of the enzyme and polymer layers used to create the biosensors enabled improvement of the mathematical model as well. Subsequent model simulations indicated that the performance characteristics achieved with the optimized biosensors approach the theoretical limits predicted for devices of this construction. Such high-performance glutamate biosensors will be more effective in vivo at a size closer to cellular dimension and will enable better correlation of glutamate signaling events with electrical recordings.
基于固定在平面铂微电极上的谷氨酸氧化酶的谷氨酸传感器的灵敏度和响应时间已被提高到接近详细数学模型预测的理论性能极限。具有阵列式电酶传感位点的微探针已成为监测体内谷氨酸和其他神经递质的有用工具；并且，作为这样的工具，它们可以用于研究许多复杂的神经疾病和障碍，包括帕金森病和药物成瘾。然而，灵敏度和响应时间不理想限制了这些有前途的研究工具的时空分辨率。一个数学模型指导了对电酶谷氨酸微传感器的系统改进，该传感器由 1-2 μm 厚的交联谷氨酸氧化酶层和下面的聚邻苯二胺和 Nafion 组成的选择渗透性涂层组成，厚度减少到小于 200 nm。这些设计修改导致灵敏度提高近 6 倍，在 37°C 时达到 320±20 nAμM cm，响应时间减少约 10 倍，达到 80±10 ms。重要的是，在保持低检测限和优异选择性的同时，实现了灵敏度和响应时间的提高。直接测量用于创建生物传感器的酶和聚合物层的传输特性也使数学模型得到了改进。随后的模型模拟表明，优化后的生物传感器的性能特征接近此类结构器件预测的理论极限。这种高性能的谷氨酸生物传感器在更接近细胞尺寸的尺寸上在体内将更有效，并能够更好地将谷氨酸信号事件与电记录相关联。
