Department of Mining and Materials Engineering, McGill University, Montréal, QC, H3A 2B2 Canada.
Biomaterials. 2012 Jan;33(1):102-8. doi: 10.1016/j.biomaterials.2011.09.039. Epub 2011 Oct 6.
Silk fibroin (SF) is extensively investigated in osteoregenerative therapy as it combines extraordinary mechanical properties and directs calcium-phosphate formation. However, the role of the peptidic fractions in inducing the protein mineralization has not been previously decoded. In this study, we investigated the mineralization of fibroin-derived polypeptides (FDPs), which were obtained through the chymotryptic separation of the hydrophobic crystalline (Cp) fractions and of the hydrophilic electronegative amorphous (Cs) fractions. When immersed in simulated body fluid (SBF), only Cs fragments demonstrated the formation of carbonated apatite, providing experimental evidence that the mineralization of SF is dictated exclusively by its electronegative amino-acidic sequences. The potential of Cs to conceptually mimic the role of anionic non-collagenous proteins in biomineralization processes was investigated via their incorporation (up to 10% by weight) in bulk osteoid-like dense collagen (DC) gels. Within 6 h in SBF, apatite was formed in DC-Cs hybrid gels, and by day 7, carbonated hydroxylapatite crystals were extensively formed. This accelerated 3-D mineralization resulted in a nine-fold increase in the compressive modulus of the hydrogel. The tailoring of the mineralization and mechanical properties of hydrogels through hybridization with FDPs could potentially have a significant impact on cell delivery and bone regenerative medicine.
丝素蛋白（SF）在骨再生治疗中被广泛研究，因为它结合了非凡的机械性能，并指导了钙磷的形成。然而，肽片段在诱导蛋白质矿化中的作用尚未被破译。在这项研究中，我们研究了丝素衍生多肽（FDP）的矿化，这些多肽是通过疏水性结晶（Cp）部分和亲水性带负电的无定形（Cs）部分的胰凝乳蛋白酶分离获得的。当浸泡在模拟体液（SBF）中时，只有 Cs 片段表现出碳酸磷灰石的形成，这为 SF 的矿化完全由其带负电的氨基酸序列决定提供了实验证据。通过将 Cs 掺入（高达 10%重量）大体积类骨质致密胶原（DC）凝胶中，研究了 Cs 概念上模拟生物矿化过程中阴离子非胶原蛋白作用的潜力。在 SBF 中 6 小时内，在 DC-Cs 杂化凝胶中形成了磷灰石，并且在第 7 天，碳酸羟基磷灰石晶体广泛形成。这种加速的 3D 矿化导致水凝胶的压缩模量增加了九倍。通过与 FDPs 杂交来调整水凝胶的矿化和机械性能，可能会对细胞输送和骨再生医学产生重大影响。
