Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University, TWIns, Tokyo, Japan.
J Chromatogr A. 2011 Dec 2;1218(48):8617-28. doi: 10.1016/j.chroma.2011.09.082. Epub 2011 Oct 6.
Poly(N-isopropylacrylamide) (PIPAAm) brush grafted silica beads, a thermo-responsive chromatographic stationary phase, were prepared through a surface-initiated atom transfer radical polymerization (ATRP) using 2-propanol, N,N-dimethylformamide (DMF), and water as reaction solvents. The rate of grafting PIPAAm on silica bead surfaces was different and found to be dependent on the reactivity of reaction solvent. Temperature-dependent elution profiles of hydrophobic steroids from the prepared-beads-packed columns were found to be different, although the graft amounts of PIPAAm were similar on silica bead surfaces. Especially, prepared beads using 2-propanol exhibited a higher resolution than those using DMF. Calibration curves using glucose and pullulan suggested that beads prepared using DMF prohibited analytes to diffuse into the pores. On the contrary, beads prepared using 2-propanol allowed analytes to diffuse into the pores. The pore diameter of the prepared beads, measured by N(2) adsorption-desorption measurement, suggested that beads using 2-propanol has relatively larger pore diameter than those using DMF. Thus, the reaction solvent in surfaces-initiated ATRP affected the grafting configuration of PIPAAm on porous silica-bead surfaces, leading to the different separation efficiency of stationary phase for bioactive compounds.
聚（N-异丙基丙烯酰胺）（PIPAAm）刷接枝硅胶珠，一种温敏色谱固定相，通过 2-丙醇、N，N-二甲基甲酰胺（DMF）和水作为反应溶剂，通过表面引发原子转移自由基聚合（ATRP）制备而成。在硅胶珠表面接枝 PIPAAm 的速率不同，并且发现其取决于反应溶剂的反应性。尽管在硅胶珠表面上 PIPAAm 的接枝量相似，但从制备的珠填充柱中疏水性甾体的温度依赖性洗脱曲线不同。特别是，使用 2-丙醇制备的珠子比使用 DMF 制备的珠子具有更高的分辨率。使用葡萄糖和普鲁兰聚糖的校准曲线表明，使用 DMF 制备的珠子会阻止分析物扩散到孔中。相反，使用 2-丙醇制备的珠子允许分析物扩散到孔中。通过氮气吸附-脱附测量测量的制备珠的孔径表明，使用 2-丙醇的珠子具有比使用 DMF 的珠子相对更大的孔径。因此，表面引发 ATRP 中的反应溶剂影响 PIPAAm 在多孔硅胶珠表面上的接枝构型，导致固定相对生物活性化合物的分离效率不同。
