title: Surface design with self-heating smart polymers for on-off switchable traps.
abstract: We have developed a novel self-heating, temperature-responsive chromatography system for the effective separation of biomolecules. Temperature-responsive poly(N-isopropylacrylamide-co-N-hydroxymethylacrylamide), poly(NIPAAm-co-HMAAm), was covalently grafted onto the surface of magnetite/silica composites as 'on-off' switchable surface traps. The lower critical solution temperature (LCST) of the poly(NIPAAm-co-HMAAm)s was controlled from 35 to 55 °C by varying the HMAAm content. Using the heat generated by magnetic particles in an alternating magnetic field (AMF) we were able to induce the hydrophilic to hydrophobic phase separation of the grafted temperature-responsive polymers. To assess the feasibility of the poly(NIPAAm-co-HMAAm)-grafted magnetite/silica particles as the stationary phase for chromatography, we packed the particles into the glass column of a liquid chromatography system and analyzed the elusion profiles for steroids. The retention time for hydrophobic steroids markedly increased in the AMF, because the hydrophobic interaction was enhanced via self-heating of the grafted magnetite/silica particles, and this effect could be controlled by changing the AMF irradiation time. Turning off the AMF shortened the total analysis time for steroids. The proposed system is useful for separating bioactive compounds because their elution profiles can be easily controlled by an AMF.
authors.affiliation: Department of Materials Engineering, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan; Biomaterials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Prapatsorn
authors.initials: P
authors.lastname: Techawanitchai
authors.affiliation: Department of Nanostructure and Advanced Materials, Graduate School of Science and Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Yamamoto
authors.affiliation: Biomaterials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Ebara
authors.affiliation: Department of Materials Engineering, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan; Biomaterials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Aoyagi
keywords: alternating magnetic field (AMF); high-performance liquid chromatography (HPLC); magnetic particle; poly(N-isopropylacrylamide); smart polymer