Chemical and Materials Engineering Department, University of Alberta, National Research Council Canada, National Institute for Nanotechnology, Edmonton, Alberta, Canada.
Biomacromolecules. 2011 Oct 10;12(10):3567-80. doi: 10.1021/bm200778u. Epub 2011 Sep 14.
Nonfouling polymer architectures are considered important to the successful implementation of many biomaterials. It is thought that how these polymers induce conformational changes in proteins upon adsorption may dictate the fate of the device being utilized. Herein, oxidized silicon nanoparticles (SiNP) were modified with various forms of poly(carboxybetaine methacrylamide) (PCBMA) for the express purpose of understanding how polymer chemistry affects film hydration, adsorbed protein conformation, and clot formation kinetics. To this end, carboxybetaine monomers differing in intercharge separating spacer groups were synthesized, and nitroxide-mediated free radical polymerization (NMP) was conducted using alkoxyamine initiators with hydrophobic (TEMPO) and hydrophilic (β-phosphonate) terminal groups. The physical properties (surface composition, thickness, grafting density, etc.) of the resulting polymer-SiNP conjugates were quantified using several techniques, including Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), and thermogravimetric analysis (TGA). The effect of spacer group on the surface charge density was determined using zeta potential measurements. Three proteins, viz., lysozyme, bovine α-lactalbumin, and human serum albumin, were used to evaluate the effect film properties (charge, hydration, end-group) have on adsorbed protein conformation, as determined by circular dichroism (CD), fluorescence spectroscopy, and fluorescence quenching techniques. Hemocompatibility of these surfaces was observed by measuring clot formation kinetics using the plasma recalcification time assay. It was found that chain chemistry, as opposed to end-group chemistry, was a major determiner for water structure, adsorbed protein conformation, and clotting kinetics. It is thought that the systematic evaluation of how both chain (internal) and end-group (external) polymer properties affect film hydration, protein conformation, and clot formation will provide valuable insight that can be applied to all engineered surfaces for biomedical applications.
无污损聚合物结构被认为对许多生物材料的成功实施至关重要。人们认为，这些聚合物在吸附时如何诱导蛋白质构象变化，可能决定所使用的装置的命运。在此，用各种形式的聚（羧酸甜菜碱甲基丙烯酰胺）（PCBMA）对氧化硅纳米粒子（SiNP）进行了修饰，目的是了解聚合物化学如何影响薄膜水合、吸附蛋白质构象和凝血形成动力学。为此，合成了带有不同间隔基的羧酸甜菜碱单体，并使用带有疏水性（TEMPO）和亲水性（β-膦酸酯）端基的烷氧基胺引发剂进行了氮氧化物介导的自由基聚合（NMP）。使用傅里叶变换红外（FTIR）光谱、动态光散射（DLS）和热重分析（TGA）等多种技术对所得聚合物-SiNP 缀合物的物理性质（表面组成、厚度、接枝密度等）进行了定量分析。使用zeta 电位测量确定了间隔基对表面电荷密度的影响。使用溶菌酶、牛α-乳白蛋白和人血清白蛋白三种蛋白质来评估薄膜性质（电荷、水合、端基）对吸附蛋白质构象的影响，方法是通过圆二色性（CD）、荧光光谱和荧光猝灭技术来确定。通过使用血浆再钙化时间测定法测量凝血形成动力学来观察这些表面的血液相容性。结果发现，链化学而不是端基化学是决定水结构、吸附蛋白质构象和凝血动力学的主要因素。人们认为，系统地评估链（内部）和端基（外部）聚合物性质如何影响薄膜水合、蛋白质构象和凝血形成动力学，将为所有用于生物医学应用的工程表面提供有价值的见解。
