Preparation And Investigation Of Thermally Switchable Chromatographic Materials Via Controlled Radical Polymerization

In the study of proteomics, affinity chromatographic materials, as a sort of selective chromatographic media, are extensively used for the removal of high abundant proteins and enrichment of low abundant proteins from complex biological sample. Recently, most researchers have focused their attention on the field of temperature-sensitive chromatography, furthermore, thermally switchable affinity chromatography is a novel separate type that captures and releses the target with convenient temperature control rather than changing the mobile phases, which results in the description of real “Green Chromatography”. However, few reports in this field have been published so far. We made a further research in the preparation of switchablely temperature-responsive affinity chromatographic materials via two kinds of controlled radical polymerization. In ATRP, as the sort of intermediate, N-acryloxysuccinimide was selected to synthesize thermally switchable affinity chromatographic materials, for the sake of the introduction of different ligands including amino groups to the polymers, and in order to establish a hyper channel of preparation of affinity chromatographic matrix. FT-IR, GPC and LCST characterizations were conducted to determine the optimum condition of synthesis of copolymer, and the mole ratio of NAS with respect to NIPAAm was 10%, the volume ratio of H2 O in solvent was 15%, in this case, the LCST of the copolymer was 23.5oC. We chose 3-aminobenzeneboronic acid served as the target ligand with amino groups to make a reaction with Silica@P(NIPAAm-co-NAS) to synthesize Silica@P(NIPAAm-co-APBA).. Good performance of HPLC analysis of Silica@P(NIPAAm-co-APBA) was that adenosine was selectively captured at 10oC and shed at 50oC, which demonstrated that we built up a rapid and convenient way of preparation of thermally switchable affinity chromatographic materials, in a certain sense which was effective. In order to meet the demand of various monomers and ligands in separation, and at the same time, to develope a new and highly effective method of preparation of temperature-responsitive chromatographic materials, RAFT emerges at the right moment. We designed a synthesized route to explore and research this new method. 4-(Chloromethyl) phenyltrichlorosilane and phenyltrichlorosilane introduced priming sites and controlled grafting density on the surface of silica, and S-benzyl dithiobenzoate acted as chain transfer agent was grafted on the cover of silica. Synthesized Silica@SC(S)Ph triggered polymerization on the appearance of silica with AIBN. FT-IR, XPS characterizations indicated the right products in each step. TGA analysis demonstrated the grafting ratio increased with a greater amount of AIBN, and the biggest was 8.88%. The increasing grafting ratio improved thermosensitivity of HPLC performance of modified silica and separation of four steroid drugs at 10oC, 30oC and 50oC. Experimental results indicated RAFT worked and provided foundation of further research.