Department of Chemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand.
Langmuir. 2010 Mar 16;26(6):4048-56. doi: 10.1021/la903506q.
A ligand with a bisphosphonate headgroup and methyl-terminated poly(ethylene oxide) 550 tail has been adsorbed to a boehmite (AlOOH) particle film from aqueous solutions at 9, 18, 26, and 40 degrees C with a range of coverages. In situ attenuated total reflectance infrared (ATR-IR) spectra of the PEO-modified boehmite particle films has been used to monitor surface coverage. PEO-related IR absorptions showed variation in band shape with coverage and temperature which reflect changes in the configuration and crowding of PEO ligand tails. The integrated absorbance of PEO-related absorptions arising from CH(2) wagging and twisting vibrations indicated the average conformation about the C-C and C-O bonds. At all values of coverage and temperature, the PEO tails of the PEO-phosphonate ligands were found to have a predominantly gauche conformation about C-C bonds and a predominantly trans conformation about C-O bonds. The proportion of PEO with this predominant configuration, termed TGT, was found to vary with coverage and temperature and was most prevalent for PEO-modified boehmite surfaces with a ligand coverage of approximately 0.95 at 18 degrees C. Dynamic water contact angle measurements showed that PEO-modified surfaces with the greatest proportion of PEO in the TGT configuration were also the most hydrophilic, thus indicating that PEO in the TGT configuration was more hydrated or polar than other configurations. Variation in the proportion of PEO in the TGT configuration with temperature and coverage have been used to explain the variable resistance to protein adhesion reported for PEO-modified surfaces. Factors influencing the configuration of surface-bound PEO with changes in ligand coverage and temperature have been discussed.
一种带有双膦酸酯头基和甲基封端聚（氧化乙烯）550 尾的配体已从水溶液中吸附到勃姆石（AlOOH）颗粒膜上，在 9、18、26 和 40°C 的温度范围内具有不同的覆盖率。原位衰减全反射红外（ATR-IR）光谱已用于监测 PEO 修饰的勃姆石颗粒膜的表面覆盖率。PEO 相关的 IR 吸收随覆盖率和温度而变化，其带形状的变化反映了 PEO 配体尾部的构象和拥挤程度的变化。PEO 相关吸收的积分吸收来自 CH(2) 摇摆和扭转振动，表明 C-C 和 C-O 键的平均构象。在所有覆盖率和温度下，PEO-膦酸酯配体的 PEO 尾部被发现 C-C 键主要呈 gauche 构象，C-O 键主要呈 trans 构象。这种主要构型的 PEO 比例，称为 TGT，发现随覆盖率和温度而变化，在 18°C 时配体覆盖率约为 0.95 的 PEO 修饰勃姆石表面最为普遍。动态水接触角测量表明，具有最大 TGT 构型 PEO 比例的 PEO 修饰表面也具有最高的亲水性，这表明 TGT 构型的 PEO 比其他构型更水合或更极性。TGT 构型 PEO 比例随温度和覆盖率的变化已被用于解释 PEO 修饰表面报道的蛋白质粘附阻力的变化。讨论了随配体覆盖率和温度变化影响表面结合 PEO 构型的因素。
