Zhang Lihong, Lipik Vitali, Miserez Ali
School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.
J Mater Chem B. 2016 Feb 28;4(8):1544-1556. doi: 10.1039/c5tb02298c. Epub 2016 Feb 8.
Sandcastle worms secrete a water-resistant proteinaceous glue that is used to bind mineral particulates into their protective tubing. Previous proteomics studies have shown that the constitutive proteins of the glue are oppositely charged co-polypeptides that form a complex coacervate precursor phase, which is critical for stable underwater delivery of the adhesive. Using ring-opening polymerization (ROP) from N-carboxyanhydride (NCA) monomers, we synthesized oppositely charged co-polypeptides that mimic the amino acid composition and molecular weight of the native glue-forming proteins. The synthesis strategy enabled the incorporation of non-standard phosphoserine (pSer) and 3,4-Dihydroxyphenylalanine (Dopa) amino acids in the co-polypeptides, thereby duplicating chemical functionalities of the native glue that are key for electrostatic complexation and adhesion. Complex coacervates were obtained from these oppositely charged co-polypeptides, thus mimicking the self-assembly process of the native adhesive secreted by the sandcastle worm. Varying the relative ratio of the co-polypeptides enabled the fine-tuning of coacervation conditions such as pH and ionic strength. Wetting and rheological characterization demonstrated that our oppositely charged co-polypeptide complexes exhibited the key features associated with coacervates, namely, low surface tension, shear thinning behaviour, and viscoelastic response, making these sandcastle worm glue-inspired polypeptide coacervates a suitable modality for water-resistant bioadhesives.
沙堡蠕虫分泌一种防水的蛋白质胶水，用于将矿物颗粒结合到它们的保护管中。先前的蛋白质组学研究表明，胶水的组成蛋白是带相反电荷的共多肽，它们形成了一种复合凝聚相前体，这对于粘合剂在水下的稳定输送至关重要。我们使用N-羧基酸酐（NCA）单体的开环聚合（ROP）方法，合成了带相反电荷的共多肽，其模仿了天然胶水形成蛋白的氨基酸组成和分子量。这种合成策略使得共多肽中能够掺入非标准的磷酸丝氨酸（pSer）和3,4-二羟基苯丙氨酸（多巴）氨基酸，从而复制了天然胶水对于静电络合和粘附至关重要的化学功能。从这些带相反电荷的共多肽中获得了复合凝聚相，从而模拟了沙堡蠕虫分泌的天然粘合剂的自组装过程。改变共多肽的相对比例能够微调凝聚条件，如pH值和离子强度。润湿性和流变学表征表明，我们带相反电荷的共多肽复合物表现出与凝聚相相关的关键特性，即低表面张力、剪切变稀行为和粘弹性响应，这使得这些受沙堡蠕虫胶水启发的多肽凝聚相成为一种适用于防水生物粘合剂的形式。
