Resin-based micropipette tip for immunochromatographic assays in urine samples.

A novel bioanalysis system based on immunochromatography was developed in connection with a nitrocellulose resin modified micropipette tip, such as ZipTip. The sandwich-type immunoassay was applied to our bioanalysis system. The simple handling of the micropipette enabled us to increase the sample volume and detect low concentrations of target antigens in urine samples. In addition, the washing procedure could also be performed easily to reduce the background signal levels. For analytical evaluations, the color intensity was captured by a flatbed scanner, and processed by a software. We have achieved the detection of human chorionic gonadotropin (hCG) and prostate-specific antigen (PSA). The detection limit of hCG was 0.5 ng/ml (0.05 ng/tip), which is comparable to that of other conventional immunochromatographic systems. Moreover, the detection of PSA was greatly improved over the existing systems with the application of different sample volumes, such as 1 ng/ml (0.2 ng/tip) in a 200 microl sample volume, and 1 ng/ml (0.3 ng/tip) in 300 microl sample volume. Our bioanalysis system is a promising candidate for application to point-of-care tests with its simple handling and high sensitivity.