Lin H B, Lewis K B, Leach-Scampavia D, Ratner B D, Cooper S L
Department of Chemical Engineering, University of Wisconsin-Madison 53706.
J Biomater Sci Polym Ed. 1993;4(3):183-98. doi: 10.1163/156856293x00519.
Variable take-off angle and cold-stage ESCA measurements were utilized to analyze the surface composition of five polyurethane block copolymers. The polymers studied included a PTMO-polyurethane control, a carboxylated version of the control polyurethane, and three different peptide grafted (GRGESY, GRGDSY, and GRGDVY) polyurethanes. On dry samples the nitrogen signal detected using ESCA decreased with increasing take-off angle (i.e. as the specimen was probed closer to the surface) for all five polymers. This was believed to be due to the depletion of nitrogen-containing urethane hard segments at the surface. For all five polymers, the surface nitrogen concentration, associated with the hard segment, increased upon hydration. A greater increase of nitrogen concentration was observed for the peptide grafted polymers which suggests that grafting of the hydrophilic peptides to the polyurethane augments the hard segment enrichment at the surface upon hydration. Upon dehydration, the nitrogen concentration decreased for all five polymers suggesting migration of the more hydrophobic PTMO soft segment to the surface. In vitro endothelial cell adhesion showed an increase of cell attachment on prehydrated RGD-containing peptide grafted polyurethanes, but not on the other polymers. This result suggests an enhancement of peptide density at the aqueous interface, in good agreement with the ESCA studies.
采用可变起飞角和冷台电子能谱分析（ESCA）测量方法，对五种聚氨酯嵌段共聚物的表面组成进行了分析。所研究的聚合物包括一种聚四氢呋喃聚氨酯对照物、该对照聚氨酯的羧化版本，以及三种不同的肽接枝（GRGESY、GRGDSY和GRGDVY）聚氨酯。对于所有五种聚合物，在干燥样品上，使用ESCA检测到的氮信号随着起飞角的增加（即随着对样品更靠近表面进行探测）而降低。这被认为是由于表面含氮聚氨酯硬段的耗尽。对于所有五种聚合物，与硬段相关的表面氮浓度在水合后增加。对于肽接枝聚合物，观察到氮浓度有更大的增加，这表明将亲水性肽接枝到聚氨酯上会增强水合后表面硬段的富集。脱水后，所有五种聚合物的氮浓度均降低，这表明疏水性更强的聚四氢呋喃软段迁移到了表面。体外内皮细胞黏附实验表明，在预水合的含RGD肽接枝聚氨酯上细胞附着增加，但在其他聚合物上没有增加。这一结果表明在水相界面处肽密度增加，与ESCA研究结果高度一致。
