Protein-Immobilized Hydrogel Microstructures for Optical Biosensing

Hydrogels are attractive support materials for protein immobilization because they provide soft and hydrated environment that is essential for proteins to maintain their structure and activity. Protein-incorporated hydrogels can be easily micropatterned via various microfabrication techniques and have great potential to be used as protein microarrays. Among the various hydrogels, this chapter mainly focuses on poly(ethylene glycol)(PEG)-based hydrogels that are prepared from acrylated PEG macromer with different molecular weights. Physical properties of PEG hydrogel can be tuned by changing the molecular weight (MW) of PEG. Planar or suspension microarrays of PEG hydrogels are fabricated by different lithographic techniques and proteins such as enzymes and antibodies are incorporated into resultant PEG hydrogel microarrays via physical entrapment or covalent surface immobilization. Hydrogel-incorporated proteins can be applied to microarray-based biosensor, where interaction between probe proteins and target molecules are monitored with absorbance or fl uorescence. Eventually, hydrogel microstructures would be integrated with microfl uidic device to achieve high-throughput and high-content protein-based analysis.