Point of care testing system via enzymatic method for the rapid, efficient assay of glycated albumin

Abstract

The ratio of glycated albumin to albumin concentration in serum is termed the glycated albumin (GA) value. The GA value provides a time-averaged index of the state of glycemic control for the previous 2 weeks. In this study, a dry chemistry system (GA monitor) via an enzymatic method was proposed in order to provide a GA value measurement for point of care testing (POCT). The GA monitor was made from three devices a set of test-tapes, a test-strip and an optical analyzer. A GA test-tape, a ketoamine test-tape and an albumin test-tape were enclosed in the fabricated test-strip. Time-course changes of the optical characteristics were evaluated using the test-strip. It was found that the three test tapes must be enclosed in the test-strip to create a dry chemistry system for small sample volumes (20 microl). A temperature control unit, which could hold the temperature of the GA test-tape at 45 degrees C and at 25 degrees C for the other two types of test-tape was incorporated into the optical analyzer. With the GA test-tape held separately and controlled at 45 degrees C, the analytical time decreased to one-third of the time taken for the three tapes at 25 degrees C. The analytical accuracy of the three types of test-tape showed favorable results, with R2 values of 0.96-0.98 and coefficients of variation (CV) of 2.4-6.8%. Compared with a commercially available liquid chemistry system, the analytical accuracy of the GA monitor exhibited a relatively favorable linearity of R=0.82. According to these results, a new GA value analytical system was realized, in which the GA value could be assayed within five minutes using only 20 microl of blood sample with a disposable test-strip. This system could potentially be used for clinical purposes as test equipment for rapid and efficient POCT.