Storage and reactivation of enzymes in a disposable, self-contained lab-on-a-chip system

For a point-of-care chip, it is important to have reactants stably stored on-chip. In this study, deposition and drying of a solution of three enzymes have been addressed. The time for diffusion/rehydration of fluorescently labelled mouse IgG in the dried enzyme solution was ~10 minutes. Microchips with native cyclic olefin copolymer (COC) surfaces showed large adsorption of mouse IgG, while polyethylene glycol (PEG) coated surfaces showed adequate protein resistance. Successful amplification on chip in 500 nl reaction chambers was obtained for spotted and dried enzymes when 0.5% PEG 8000 was applied.