Zhou Shun, Huang Wenwen, Belton David J, Simmons Leo O, Perry Carole C, Wang Xiaoqin, Kaplan David L
National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, PR China; Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA.
Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA.
Acta Biomater. 2015 Mar;15:173-80. doi: 10.1016/j.actbio.2014.10.040. Epub 2014 Nov 4.
In the present study, an artificial spider silk gene, 6mer, derived from the consensus sequence of Nephila clavipes dragline silk gene, was fused with different silica-binding peptides (SiBPs), A1, A3 and R5, to study the impact of the fusion protein sequence chemistry on silica formation and the ability to generate a silk-silica composite in two different bioinspired silicification systems: solution-solution and solution-solid. Condensed silica nanoscale particles (600-800 nm) were formed in the presence of the recombinant silk and chimeras, which were smaller than those formed by 15mer-SiBP chimeras, revealing that the molecular weight of the silk domain correlated to the sizes of the condensed silica particles in the solution system. In addition, the chimeras (6mer-A1/A3/R5) produced smaller condensed silica particles than the control (6mer), revealing that the silica particle size formed in the solution system is controlled by the size of protein assemblies in solution. In the solution-solid interface system, silicification reactions were performed on the surface of films fabricated from the recombinant silk proteins and chimeras and then treated to induce β-sheet formation. A higher density of condensed silica formed on the films containing the lowest β-sheet content while the films with the highest β-sheet content precipitated the lowest density of silica, revealing an inverse correlation between the β-sheet secondary structure and the silica content formed on the films. Intriguingly, the 6mer-A3 showed the highest rate of silica condensation but the lowest density of silica deposition on the films, compared with 6mer-A1 and -R5, revealing antagonistic crosstalk between the silk and the SiBP domains in terms of protein assembly. These findings offer a path forward in the tailoring of biopolymer-silica composites for biomaterial related needs.
在本研究中,将源自金蛛(Nephila clavipes)拖牵丝基因共有序列的人工蜘蛛丝基因6mer与不同的硅结合肽(SiBPs)A1、A3和R5融合,以研究融合蛋白序列化学对二氧化硅形成的影响,以及在两种不同的仿生硅化系统(溶液-溶液和溶液-固体)中生成丝-二氧化硅复合材料的能力。在重组丝和嵌合体存在的情况下形成了凝聚态的纳米级二氧化硅颗粒(600-800纳米),这些颗粒比由15mer-SiBP嵌合体形成的颗粒小,这表明丝结构域的分子量与溶液系统中凝聚态二氧化硅颗粒的大小相关。此外,嵌合体(6mer-A1/A3/R5)产生的凝聚态二氧化硅颗粒比对照(6mer)小,这表明溶液系统中形成的二氧化硅颗粒大小受溶液中蛋白质聚集体大小的控制。在溶液-固体界面系统中,在由重组丝蛋白和嵌合体制成的薄膜表面进行硅化反应,然后进行处理以诱导β-折叠的形成。在β-折叠含量最低的薄膜上形成了更高密度的凝聚态二氧化硅,而β-折叠含量最高的薄膜沉淀出最低密度的二氧化硅,这表明β-折叠二级结构与薄膜上形成的二氧化硅含量之间呈负相关。有趣的是,与6mer-A1和-R5相比,6mer-A3在薄膜上显示出最高的二氧化硅凝聚速率,但二氧化硅沉积密度最低,这表明在蛋白质组装方面,丝和SiBP结构域之间存在拮抗相互作用。这些发现为针对生物材料相关需求定制生物聚合物-二氧化硅复合材料提供了一条前进的道路。