Electrical and Computer Engineering, University of Connecticut, 371 Fairfield Way, Storrs, CT 06269, USA.
Sensors (Basel). 2012 Oct 1;12(10):13402-16. doi: 10.3390/s121013402.
The performance of implantable electrochemical glucose sensors is highly dependent on the flux-limiting (glucose, H(2)O(2), O(2)) properties of their outer membranes. A careful understanding of the diffusion profiles of the participating species throughout the sensor architecture (enzyme and membrane layer) plays a crucial role in designing a robust sensor for both in vitro and in vivo operation. This paper reports the results from the mathematical modeling of Clark's first generation amperometric glucose sensor coated with layer-by-layer assembled outer membranes in order to obtain and compare the diffusion profiles of various participating species and their effect on sensor performance. Devices coated with highly glucose permeable (HAs/Fe(3+)) membranes were compared with devices coated with PSS/PDDA membranes, which have an order of magnitude lower permeability. The simulation showed that the low glucose permeable membrane (PSS/PDDA) sensors exhibited a 27% higher amperometric response than the high glucose permeable (HAs/Fe(3+)) sensors. Upon closer inspection of H(2)O(2)diffusion profiles, this non-typical higher response from PSS/PDDA is not due to either a larger glucose flux or comparatively larger O(2) concentrations within the sensor geometry, but rather is attributed to a 48% higher H(2)O(2) concentration in the glucose oxidase enzyme layer of PSS/PDDA coated sensors as compared to HAs/Fe(3+) coated ones. These simulated results corroborate our experimental findings reported previously. The high concentration of H(2)O(2) in the PSS/PDDA coated sensors is due to the low permeability of H(2)O(2) through the PSS/PDDA membrane, which also led to an undesired increase in sensor response time. Additionally, it was found that this phenomenon occurs for all enzyme thicknesses investigated (15, 20 and 25 nm), signifying the need for a holistic approach in designing outer membranes for amperometric biosensors.
植入式电化学葡萄糖传感器的性能高度依赖于其外膜的限流器（葡萄糖、H2O2、O2）特性。仔细了解参与物质在传感器结构（酶和膜层）中的扩散分布，对于设计用于体外和体内操作的稳健传感器至关重要。本文报告了通过对涂有层层组装外膜的克拉克第一代电流型葡萄糖传感器进行数学建模的结果，以获得和比较各种参与物质的扩散分布及其对传感器性能的影响。与具有数量级低渗透性的 PSS/PDDA 膜相比，涂有高葡萄糖渗透性（HA/Fe3+）膜的器件具有更高的电流响应。通过更仔细地检查 H2O2 的扩散分布，发现低葡萄糖渗透性（PSS/PDDA）传感器的电流响应比高葡萄糖渗透性（HA/Fe3+）传感器高 27%，这一非典型的更高响应并非由于葡萄糖通量更大或传感器几何形状内的 O2 浓度更高，而是由于 PSS/PDDA 涂层传感器中的葡萄糖氧化酶层中 H2O2 浓度高 48%，而 HA/Fe3+ 涂层传感器中 H2O2 浓度低。这些模拟结果与我们之前报道的实验结果相符。PSS/PDDA 涂层传感器中 H2O2 浓度较高，是由于 H2O2 通过 PSS/PDDA 膜的渗透性较低所致，这也导致传感器响应时间的不期望增加。此外，还发现这种现象发生在所有研究的酶厚度（15、20 和 25nm）上，这表明需要在设计电流型生物传感器的外膜时采用整体方法。
