Polymers are readily micro- and nanopatterned onto surfaces using electron beam (e-beam) lithography, which cross-linked the chains to the surface.  We exploit this to prepare functionalized surfaces that can be used to immobilize proteins.  For example, if poly(ethylene glycol) with functional end groups are utilized, then proteins are readily immobilized on the resulting surface-bound hydrogels. Since conjugating proteins on surfaces in specific orientations is important for retention of bioactivity, initially, poly(ethylene glycol)s (PEGs) were synthesized with biotin, aminooxy, maleimide, and nitrilotriacetic acid (NTA) end groups.  As a result, proteins conjugated to the surface features via ligand binding sites, N-terminal oxoamides, free cysteines, and histidine tags, respectively.  Patterns of different proteins side by side and in three-dimensional arrangements are readily made.  We also can pattern oligo(ethylene glycol) methacrylate-based thermoresponsive polymers with amine end-groups.  The lower critical solution temperatures (LCSTs) of the polymers were readily adjusted by altering the length of oligo(ethylene glycol) side chains or by changing the ratio of monomers with different lengths.  The polymers were patterned on silicon surfaces by electron beam lithography, followed by the conjugation of self-quenching fluorophores to the patterned hydrogels utilizing the amine end-groups. At room temperature, the hydrogels were brightly fluorescent in water. Upon increasing the temperature to values above the volume phase transition temperature (VPTT) of the respective gel, a dramatic decrease in the fluorescence intensity was observed due to self-quenching of fluorophores in the collapsed state of the gel. Importantly, the temperature-induced fluorescence switch was reversible. In this way, we generated morphing structures that reversibly display different messages at different temperatures.  Fabrication of the surfaces and application in enzyme cascades, cell adhesion, and encryptic messages will be discussed.

Functionalized polymeric surfaces generated by electron beam lithography for applications from encryptic messages to enhanced cell adhesion

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.