Ye Mingming, Jiang Rui, Zhao Jin, Zhang Juntao, Yuan Xubo, Yuan Xiaoyan
School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin, 300072, China.
Department of Polymer Materials, School of Materials Science and Engineering, Tianjin University, Tianjin, 300072, People's Republic of China.
J Mater Sci Mater Med. 2015 Dec;26(12):273. doi: 10.1007/s10856-015-5608-y. Epub 2015 Oct 30.
Adhesives with catechol moieties have been widely investigated in recent years. However, actually how much catechol groups for these mussel bio-inspired adhesives, especially in their natural form under physiological condition, is appropriate to bond with organic substrates has not been studied intensively. This study blends ε-polylysine (PL), featuring laterally grafted catechols under physiological conditions (pH 7.4), with oxidized dextran to form a hydrogel in situ via the Schiff base without introducing small cytotoxic molecules as crosslinking agents. It finds that the amount of catechol groups imposes an obvious influence on gelation time, swelling behavior, and hydrogel morphology. Both the storage modulus and adhesion strength are found to increase first and decrease afterwards with an increase of pendent catechol content. Furthermore, catechol hydrogen interactions and the decrease in the crosslink density derived from the decrease of amino groups on PL are simultaneously found to affect the storage modulus. Meanwhile, multiple hydrogen-bonding interactions of catechol with amino, hydroxyl, and carboxyl groups, which are in abundance on the surface of tissue, are mainly found to provide an adhesive force. The study finds that with more catechol, there is a greater chance that the cohesive force will weaken, making the entire adhesion strength of the hydrogel decrease. Using a cytotoxicity test, the nontoxicity of the hydrogel towards the growth of L929 cells is proven, indicating that hydrogels have potential applications in soft tissue repair under natural physiological conditions.
近年来，含有儿茶酚基团的粘合剂受到了广泛研究。然而，实际上这些受贻贝启发的粘合剂，尤其是在生理条件下的天然形式中，究竟有多少儿茶酚基团适合与有机底物结合，尚未得到深入研究。本研究将ε-聚赖氨酸（PL）与氧化葡聚糖混合，PL在生理条件（pH 7.4）下具有侧向接枝的儿茶酚，通过席夫碱原位形成水凝胶，且不引入具有细胞毒性的小分子作为交联剂。研究发现，儿茶酚基团的数量对凝胶化时间、溶胀行为和水凝胶形态有明显影响。随着侧链儿茶酚含量的增加，储能模量和粘附强度均先增加后降低。此外，同时发现儿茶酚氢键相互作用以及由于PL上氨基减少导致的交联密度降低会影响储能模量。同时，主要发现儿茶酚与组织表面大量存在的氨基、羟基和羧基之间的多重氢键相互作用提供了粘附力。研究发现，儿茶酚越多，内聚力减弱的可能性就越大，从而使水凝胶的整体粘附强度降低。通过细胞毒性测试，证明了该水凝胶对L929细胞生长无毒，表明水凝胶在自然生理条件下的软组织修复中具有潜在应用价值。
