Attachment of hydrogel microstructures and proteins to glass via thiol-terminated silanes

Micropatterning strategies often call for attachment of non-fouling biomaterials and immobilization of proteins in order to create biosensing surfaces or to control cell-surface interactions. Our laboratory has made frequent use of hydrogel photolithography - a micropatterning process for immobilizing poly(ethylene glycol) (PEG) hydrogel microstructures on glass surfaces. In the present study we explored the use of thiolsilane as a coupling layer for both covalent anchoring of hydrogel microstructures and covalent immobilization of proteins on glass. These new surfaces were compared to acryl-silane functionalized glass slides that allowed covalent attachment of gels but only physical adsorption of proteins as well as surfaces containing a mixture of both functional groups. We observed comparable attachment and retention of hydrogel microstructures on acryl and thiol-terminated silanes. Ellipsometry studies revealed presence of significantly higher level of proteins on thiol-functionalized glass. Overall, our studies demonstrate that thiol-silane functionalized glass surfaces may be used to create complex micropatterned surfaces comprised of covalently attached hydrogels and proteins. This simple and effective surface modification strategy will be broadly applicable in cellular engineering and biosensing studies employing hydrogel micropatterns.