Fabrication and anti-fouling properties of photochemically and thermally immobilized poly(ethylene oxide) and low molecular weight poly(ethylene glycol) thin films

Poly(ethylene oxide) (PEO) and low molecular weight poly(ethylene glycol) (PEG) were covalently immobilized on silicon wafers and gold films by way of the CH insertion reaction of perfluorophenyl azides (PFPAs) by either photolysis or thermolysis. The immobilization does not require chemical derivatization of PEO or PEG, and polymers of different molecular weights were successfully attached to the substrate to give uniform films. Microarrays were also generated by printing polymer solutions on PFPA-functionalized wafer or Au slides followed by light activation. For low molecular weight PEG, the immobilization was highly dependent on the quality of the film deposited on the substrate. While the spin-coated and printed PEG showed poor immobilization efficiency, thermal treatment of the PEG melt on PFPA-functionalized surfaces resulted in excellent film quality, giving, for example, a grafting density of 9.2 × 10−4Å−2 and an average distance between grafted chains of 33 Å for PEG 20,000. The anti-fouling property of the films was evaluated by fluorescence microscopy and surface plasmon resonance imaging (SPRi). Low protein adsorption was observed on thermally-immobilized PEG whereas the photoimmobilized PEG showed increased protein adsorption. In addition, protein arrays were created using polystyrene (PS) and PEG based on the differential protein adsorption of the two polymers.

Poly(ethylene oxide) and low molecular weight poly(ethylene glycol) were covalently immobilized on silicon wafers and gold films via the CH insertion reaction of perfluorophenyl azides by either photolysis or thermolysis. High grafting density was observed for the thermally-immobilized films, which also showed the lowest protein adsorption by surface plasmon resonance imaging.Figure optionsDownload high-quality image (55 K)Download as PowerPoint slideResearch highlights
► A simple, fast, and general method for the immobilization of un-derivatized PEO and PEG films using perfluorophenyl azides.
► High grafting density comparable to PEG films prepared by other graft-to approach.
► Lowest protein adsorption on thermally-immobilized films, corresponding to the highest film thickness and quality.