The integration of immunoassays in microfluidic devices is a rapidly developing research area combining the power of immunoassays with the inherent benefits of microfluidics. Here, a general overview of microfluidic-based immunoassays is presented along with a method for immobilizing antibodies in polyacrylamide gel plugs set in microfluidic channels. These antigen-specific hydrogels can be rapidly formed by photopolymerizing monomer solutions mixed with antibodies or other large proteins. The resulting antigen-specific hydrogels contain pore sizes appropriate for physical entrapment of large antibodies while remaining permeable to smaller proteins. The open structure of these hydrogels enables the capture and concentration of target antigens present at low concentrations. Such physical entrapment provides a conceptually simple method of immobilization compared with immobilization of proteins on surfaces and offers advantages such as resistance to chemical and thermal denaturation.
