Drnovšek N, Kocen R, Gantar A, Drobnič-Košorok M, Leonardi A, Križaj I, Rečnik A, Novak S
Department for Nanostructured Materials, Jožef Stefan Institute, Ljubljana, Slovenia.
J Mater Chem B. 2016 Oct 28;4(40):6597-6608. doi: 10.1039/c6tb01101b. Epub 2016 Oct 4.
In the search for suitable scaffold materials for tissue regeneration, silk fibroin has become one of the most promising candidates due to its biocompatibility and good physical properties. To facilitate bone formation in osteochondral defects, it is often combined with a bone promoting additive. Here we demonstrate using HRTEM analysis how the release of Ca ions from bioactive glass or Ca-salts results in the reduction of β-sheet domain size that effectively controls a scaffold's properties, such as degradation and mechanical stiffness. We show that these changes already occur in silk fibroin solution prior to scaffold preparation and are caused by a decrease in zeta potential that forces fibroin molecules into tighter packing resulting in higher scaffold crystallinity, smaller β-sheet domains and higher interconnectivity. The reduction of β-sheet domains improves the elastic modulus and allows faster degradation despite the higher crystallinity. Ca was also shown to be beneficial to the formation of hydroxy-apatite sheets on the fibroin surface.
在寻找用于组织再生的合适支架材料时，丝素蛋白因其生物相容性和良好的物理性能，已成为最有前景的候选材料之一。为促进骨软骨缺损处的骨形成，它常与促进骨生长的添加剂结合使用。在此，我们通过高分辨率透射电子显微镜（HRTEM）分析表明，生物活性玻璃或钙盐中钙离子的释放如何导致β-折叠结构域尺寸减小，从而有效控制支架的性能，如降解和机械刚度。我们发现，这些变化在制备支架之前就已在丝素蛋白溶液中发生，并且是由ζ电位降低引起的，ζ电位降低迫使丝素蛋白分子更紧密地堆积，从而导致更高的支架结晶度、更小的β-折叠结构域和更高的互连性。β-折叠结构域的减少提高了弹性模量，并且尽管结晶度较高，但仍能实现更快的降解。钙还被证明有利于在丝素蛋白表面形成羟基磷灰石片层。
