Selective protein patterning in microfluidic channels using a parylene lift-off process

This paper describes a method for patterning proteins selectively using a combination of microfluidics and a lift-off process. Microchannels are used to introduce different protein solutions, allowing us to immobilize spots of proteins on a substrate. We fabricated microfluidic channels in polymethylmethacrylate (PMMA) substrate and deposited a thin parylene film as a mask containing small holes patterned on the PMMA layer. Solutions of proteins were introduced in channels and immobilized on the PMMA surface at positions defined by the parylene mask. The parylene mask was lifted-off, leaving different proteins and/or nanoparticles patterned on a PMMA substrate. Using microfluidic channel, different kinds of samples were able to be delivered and patterned on a same substrate in the wet condition; this method avoids denaturing of proteins without nonspecific binding.