A sensitive point-of-care testing chip utilizing superabsorbent polymer for the early diagnosis of infectious disease

Abstract

We developed a highly sensitive point-of-care testing (POCT) chip using an antigen-antibody complex reaction for the early diagnosis of infectious disease. The central concept of the chip was to balance the sensitivity enhancement with appropriate safety measures for infectious risk during POCT. The chip consisted of a sheet of glass fiber sealed in a polymethylmethacrylate microfluidic channel. Antibody-immobilized microbeads were accumulated in a transparent location in the channel that served as the test line, trapping the target antigen bound to fluorescently labeled antibodies and allowing diagnosis by a portable fluorescence scanner. In this work, we applied a superabsorbent polymer to drive a stable and continuous fluidic flow for both the sample and a rinsing solution without an external power supply. The generated flow enabled thorough bound/free separation of the antigen-antibody interactions and significantly improved the signal-to-noise ratio and the reproducibility. Moreover, the polymer had the advantage of retaining the potentially infectious sample within the chip, contributing to its safety for practical use. An influenza test using a virus protein exhibited a sensitivity enhancement of more than a thousand-fold compared with commercial immunochromatographic test strips.