Gold Nanoparticle Assembly Microfluidic Reactor for Efficient On-line Proteolysis*□S

A microchip reactor coated with a gold nanoparticle net-work entrapping trypsin was designed for the efficient on-line proteolysis of low level proteins and complex ex-tracts originating from mouse macrophages. The nano-structured surface coating was assembled via a layer-by-layer electrostatic binding of poly(diallyldimethylammonium chloride) and gold nanoparticles. The assembly process was monitored by UV-visible spectroscopy, atomic force microscopy, and quartz crystal microbalance. The con-trolled adsorption of trypsin was theoretically studied on the basis of the Langmuir isotherm model, and the fitted max and K values were estimated to be 1.2 10 7 mol/m2 and 4.1 105 M1, respectively. An enzymatic kinetics assay confirmed that trypsin, which was en