Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA.
Biosens Bioelectron. 2010 Jan 15;25(5):1075-81. doi: 10.1016/j.bios.2009.09.026. Epub 2009 Oct 12.
Luminescent microspheres encapsulating glucose oxidase have recently been reported as potential implantable sensors, but the operational lifetime of these systems has been limited by enzyme degradation. We report here that the longevity of these enzymatic microparticle-based sensors has been extended by the coimmobilization of glucose oxidase (GOx) and catalase (CAT) into the sensor matrix. A mathematical model was used to compare the response and longevity of the sensors with and without catalase. To experimentally test the longevity, sensors were continuously operated under normoglycemic dermal substrate concentrations and physiological conditions (5.5 mM glucose and 140 microM O(2), 37 degrees C and pH 7.4). The sensors incorporating CAT were experimentally shown to be approximately 5 times more stable than those without CAT; nevertheless, the response of sensors with CAT still changed by approximately 20%, when operated continuously for 7 days. The experimentally determined trends obtained for the variation in sensor response due to enzyme deactivation were in close agreement with modeling predictions, which also revealed a significant apparent loss in enzyme activity upon immobilization. It was further predicted via modeling that by incorporating 0.1 mM each of active GOx and CAT, the sensors will exhibit less than 2% variation in response over 1 month of continuous operation.
最近有报道称，内包葡萄糖氧化酶的发光微球可用作潜在的可植入传感器，但这些系统的工作寿命一直受到酶降解的限制。我们在此报告，通过将葡萄糖氧化酶（GOx）和过氧化氢酶（CAT）共固定在传感器基质中，这些基于酶的微粒传感器的寿命得以延长。我们使用数学模型比较了具有和不具有过氧化氢酶的传感器的响应和寿命。为了实验测试其耐久性，传感器在正常血糖皮肤基质浓度和生理条件（5.5mM 葡萄糖和 140μM O2，37°C 和 pH7.4）下连续运行。实验表明，与不含 CAT 的传感器相比，含有 CAT 的传感器大约稳定 5 倍；然而，当连续运行 7 天时，带有 CAT 的传感器的响应仍变化约 20%。由于酶失活而导致传感器响应变化的实验确定趋势与建模预测非常吻合，建模预测还表明，固定化后酶活性明显丧失。通过建模进一步预测，通过共固定 0.1mM 的活性 GOx 和 CAT，传感器在连续运行 1 个月内的响应变化将小于 2%。
