Jenkins Daniel M, Delwiche Michael J
Department of Biological and Agricultural Engineering, University of California, 3048 Bainer Hall, Davis, CA 95616, USA.
Biosens Bioelectron. 2003 Jan;18(1):101-7. doi: 10.1016/s0956-5663(02)00140-9.
A manometric sensor previously developed to measure urea was modified to measure glucose and lactose through enzymatic oxidation. Change in pressure in an enclosed cavity was correlated to the depletion of oxygen resulting from the enzymatic oxidation of glucose or lactose. The response of the sensor was linear and could be made adjustable over a large range by adjusting the amount of sample loaded into the fixed volume reactor. Because of the slow mutarotation of glucose, the oxidation of glucose was not allowed to proceed to completion. Therefore, the precision of the sensor (approximately 0.2 mM in a range from 0 to 5 mM) was limited by variations in the oxidation rate of glucose by glucose oxidase. Because the assay for lactose measured glucose subsequent to the hydrolysis of lactose by beta-galactosidase, the same degree of precision was observed in lactose. Milk lactose, typically at concentrations of about 150 mM, was estimated using the lactose assay after first diluting the samples. For many fluids such as milk, the use of manometric sensors for oxidizable substrates may be preferable to optical and electrochemical methods because they are robust and suffer a low degree of optical and chemical interferences. Glucose and lactose are representative of many important oxidizable substrates, which may be determined in this manner, many of which do not suffer from limitations caused by mutarotation. In theory, detection limits less than 1 microM may be achieved using these methods.
一种先前开发用于测量尿素的测压传感器经过改进，通过酶促氧化来测量葡萄糖和乳糖。封闭腔体内的压力变化与葡萄糖或乳糖酶促氧化导致的氧气消耗相关。该传感器的响应呈线性，通过调整装入固定体积反应器中的样品量，可在很大范围内进行调节。由于葡萄糖的变旋作用缓慢，葡萄糖的氧化不允许进行到完全。因此，传感器的精度（在0至5 mM范围内约为0.2 mM）受到葡萄糖氧化酶对葡萄糖氧化速率变化的限制。由于乳糖测定是在β-半乳糖苷酶水解乳糖后测量葡萄糖，所以在乳糖测量中观察到了相同程度的精度。首先对样品进行稀释后，使用乳糖测定法对通常浓度约为150 mM的牛奶乳糖进行了估算。对于许多流体，如牛奶，使用测压传感器测量可氧化底物可能比光学和电化学方法更可取，因为它们坚固耐用，且受到的光学和化学干扰程度较低。葡萄糖和乳糖是许多重要可氧化底物的代表，可以用这种方式进行测定，其中许多底物不受变旋作用引起的限制。理论上，使用这些方法可以实现低于1 microM的检测限。
