A chemical timer for a direct-reading reagent test strip changes color a predetermined time after a biological fluid is applied to the strip. The strip measures the concentration of an analyte in the fluid. The timer is a dry coating of an indicator, an enzyme-containing reagent that when hydrated can react with glucose to change the color of the indicator, an inhibitor to inhibit the change in color of the indicator, glucose, and optionally, an aldose that does not react with the enzyme in the reagent. Preferably, the reagent and glucose are present in excess in the coating, and the time it takes for the timer color to change can be controlled by the inhibitor concentration. The aldose provides timer stability, probably by interfering with glycosylation by the glucose in the dry state.
直读试剂试纸的
化学计时器在
生物液体涂抹到试纸上后,会在预定时间内改变颜色。试纸可测量液体中分析物的浓度。定时器是由指示剂、含酶试剂、抑制指示剂颜色变化的
抑制剂和
葡萄糖组成的干涂层,含酶试剂在
水合时可与
葡萄糖反应使指示剂变色,
抑制剂可选择不与试剂中的酶反应的醛糖。最好在涂层中加入过量的试剂和
葡萄糖,定时器颜色变化的时间可由
抑制剂浓度控制。醛糖可能是通过干扰
葡萄糖在干燥状态下的糖基化作用,从而提供定时器的稳定性。