title: Variations of wettability and protein adsorption on solid siliceous carriers grafted with poly(N-isopropylacrylamide).
abstract: Poly(N-isopropylacrylamide), a thermally responsive polymer, was end-grafted to mercaptopropyl derivatives of silica gel, plane glass sheets and glass capillary tubing by free radical polymerization of the monomer in 1,4-dioxane at 100 degrees C. The polymer monolayer attached to the glass carriers provided them with thermally controlled wettability registered by two independent methods: direct measurements of the water contact angle and capillary rise. The water contact angle changed from 54+/-3 degrees to 68+/-3 degrees in the temperature range from 20 to 50 degrees C. The polymer grafting to silica gel (pore diameter 100 A, particle size 5 microm) resulted in 15-30-fold reduction in protein adsorption on the carrier at 35 degrees C. Adsorption isotherms of myoglobin indicate completely different characters of the protein adsorption to silica gel and its polyNIPAM-grafted derivative. Cooling of the grafted carrier containing adsorbed myoglobin to 9 degrees C led to a partial release of the protein to the contacting solution, whereas heating of the system to 35 degrees C resulted in reversible binding of the protein. Adsorption of myoglobin on polyNIPAM-coated silica was ca. 2-fold higher at 35 than at 9 degrees C, most probably due to steric repulsion displayed by the swollen copolymer at the lower temperature.
authors.affiliation: Department of Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-22100 Lund, Sweden.
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Ivanov
authors.forename: Johan
authors.initials: J
authors.lastname: Ekeroth
authors.forename: Lars
authors.initials: L
authors.lastname: Nilsson
authors.forename: Bo
authors.initials: B
authors.lastname: Mattiasson
authors.forename: Björn
authors.initials: B
authors.lastname: Bergenståhl
authors.forename: Igor Yu
authors.initials: IY
authors.lastname: Galaev
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D000180:Acrylic Resins; D000327:Adsorption; D000818:Animals; D006736:Horses; D009211:Myoglobin / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D058428:Silica Gel; D012822:Silicon Dioxide / Q000737:chemistry*; D013696:Temperature; D017155:Wettability
chemical_list: D000178:Acrylamides; D000180:Acrylic Resins; D009211:Myoglobin; D011108:Polymers; C052970:poly-N-isopropylacrylamide; D058428:Silica Gel; D012822:Silicon Dioxide