Cross-linked chitosan biofunctionalized paper-based microfluidic device towards long term stabilization of blood typing antibodies.

Long term stability of antibodies at room temperature is a major challenge in the commercialization of point-of-care devices for diagnostics. Since chitosan has been proven to be an excellent biofunctionalization material, the effects of four different biofunctionalization processes were studied to improve the room temperature stability of antibodies immobilized on chitosan modified paper-based microfluidic devices using blood typing antibodies as candidates. The devices used in this work have a flower-shaped design with 4 test zones at each corner. In three zones Anti-A, Anti-B, and Anti-D (Anti-Rh) antibodies are immobilized and the fouth zone represents the control (no antibodies) after biofunctionalization. The biofunctionalization of the paper devices was done with chitosan and chitosan cross-linked with sodium triphosphate pentabasic, glutaraldehyde, and sodium hydroxide. These devices were used for blood typing assays using real blood samples. A similar assay was also performed on unmodified (non-biofunctionalized) paper devices for comparison. Chitosan based biofunctionalized paper-devices showed better stability, up to 100 days as compared to 14 days on unmodified paper, at room temperature. Such biofunctionalized paper-based devices will be suitable for on-field and remote testing without any technical expertise and requirement for the cold chain.