Bernstein-Levi Ortal, Ochbaum Guy, Bitton Ronit
Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel; Ilze Kats Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
Colloids Surf B Biointerfaces. 2016 Jan 1;137:214-20. doi: 10.1016/j.colsurfb.2015.06.042. Epub 2015 Jul 9.
Covalently modified polysaccharides are routinely used in tissue engineering due to their tailored biofunctionality. Understanding the effect of single-chain level modification on the solution conformation of the single chain, and more importantly on the self-assembly and aggregation of the ensemble of chains is expected to improve our ability to control network topology and the properties of the resulting gels. Attaching an RGD peptide to a polysaccharide backbone is a common procedure used to promote cell adhesion in hydrogel scaffolds. Recently it has been shown that the spatial presentation of the RGD sequences affects the cell behavior; thus, understanding the effects of grafted RGD on the conformational properties of the solvated polysaccharide chains is a prerequisite for rational design of polysaccharide-peptide based biomaterials. Here we investigate the effect of covalently linked G4RGDS on the conformational state of the individual chain and chain assemblies of alginate, chitosan, and hyaluronic acid (HA) in aqueous solutions. Two peptide fractions were studied using small-angle X-ray scattering (SAXS) and rheology. In all cases, upon peptide conjugation structural differences were observed. Analysis of the scattering data shows evidence of clustering for a higher fraction of bound peptide. Moreover for all three polysaccharides the typical shear thinning behavior of the natural polysaccharide solutions is replaced by a Newtonian fluid behavior for the lower fraction conjugated peptide while a more pronounced shear thinning behavior is observed for the higher fraction. These results indicate that the fraction of the bounded peptide, determines the behavior of a polysaccharide-peptide conjugates in solution, regardless of the specific nature of the polysaccharide.
共价修饰的多糖因其定制的生物功能而经常用于组织工程。了解单链水平修饰对单链溶液构象的影响，更重要的是对链集合的自组装和聚集的影响，有望提高我们控制网络拓扑结构和所得凝胶性质的能力。将RGD肽连接到多糖主链上是在水凝胶支架中促进细胞粘附的常用方法。最近的研究表明，RGD序列的空间呈现会影响细胞行为；因此，了解接枝的RGD对溶剂化多糖链构象性质的影响是合理设计基于多糖-肽的生物材料的先决条件。在这里，我们研究了共价连接的G4RGDS对藻酸盐、壳聚糖和透明质酸（HA）在水溶液中的单链和链组装体构象状态的影响。使用小角X射线散射（SAXS）和流变学研究了两种肽级分。在所有情况下，肽缀合后均观察到结构差异。散射数据分析表明，较高比例的结合肽存在聚集迹象。此外，对于所有三种多糖，天然多糖溶液典型的剪切变稀行为在较低比例的缀合肽情况下被牛顿流体行为所取代，而在较高比例时观察到更明显的剪切变稀行为。这些结果表明，结合肽的比例决定了多糖-肽缀合物在溶液中的行为，而与多糖的具体性质无关。
