Use of PLL-g-PEG in micro-fluidic devices for localizing selective and specific protein binding

By utilizing flow-controlled PLL-g-PEG and PLL-g-PEGbiotin modification of predefined regions of a poly-(dimethylsiloxane) (PDMS) micro-fluidic device, with an intentionally chosen large (similar to 1 cm(2)) internal surface area, we report rapid (10 min), highly localized (6 x 10(-6) cm(2)), and specific surface-based protein capture from a sample volume (100 mu L) containing a low amount of protein (160 attomol in pure buffer and 400 attomol in serum). The design criteria for this surface modification were achieved using QCM-D (quartz crystal microbalance with energy dissipation monitoring) of serum protein adsorption onto PLL-g-PEG-modified oxidized PDMS. Equally good, or almost as good, results were obtained for oxidized SU-8, Topas, and poly(methyl metacrylate) (PMMA), demonstrating the generic potential of PLL-g-PEG for surface modification in various micro-fluidic applications.