title: Morphing hydrogel patterns by thermo-reversible fluorescence switching.
abstract: Stimuli responsive surfaces that show reversible fluorescence switching behavior in response to temperature changes were fabricated. Oligo(ethylene glycol) methacrylate thermoresponsive polymers with amine end-groups were prepared by atom transfer radical polymerization (ATRP). The polymers were patterned on silicon surfaces by electron beam (e-beam) lithography, followed by conjugation of self-quenching fluorophores. Fluorophore conjugated hydrogel thin films were bright when the gels were swollen; upon temperature-induced collapse of the gels, self-quenching of the fluorophores led to significant attenuation of fluorescence. Importantly, the fluorescence was regained when the temperature was cooled. The fluorescence switching behavior of the hydrogels for up to ten cycles was investigated and the swelling-collapse was verified by atomic force microscopy. Morphing surfaces that change shape several times upon increase in temperature were obtained by patterning multiple stimuli responsive polymers.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California, 90095, USA; California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California, 90095, USA.
authors.forename: Erhan
authors.initials: E
authors.lastname: Bat
authors.forename: En-Wei
authors.initials: EW
authors.lastname: Lin
authors.forename: Sina
authors.initials: S
authors.lastname: Saxer
authors.forename: Heather D
authors.initials: HD
authors.lastname: Maynard
mesh_terms: D005456:Fluorescent Dyes / Q000737:chemistry; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D008689:Methacrylates / Q000737:chemistry; D018625:Microscopy, Atomic Force; D008856:Microscopy, Fluorescence; D058105:Polymerization; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
chemical_list: D005456:Fluorescent Dyes; D008689:Methacrylates; D011108:Polymers; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate
keywords: electron beam lithography; fluorescence; oligo­(ethylene glycol); stimuli-responsive surfaces; thermo-responsive polymers