A Biomimetic Composite from Solution Self-Assembly of Chitin Nanofibers in a Silk Fibroin Matrix
A Biomimetic Composite from Solution Self-Assembly of Chitin Nanofibers in a Silk Fibroin Matrix
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DOI：
10.1002/adma.201301429
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发表时间：
2013-08-27
影响因子：
29.4
通讯作者：
Rolandi, Marco
中科院分区：
文献类型：
--
作者：
Jin, Jungho;Hassanzadeh, Pegah;Rolandi, Marco
天然结构材料[1，2]，如骨骼，牙齿，木材，节肢动物角质层，[3，4]甲壳动物外骨骼[5]和软体动物壳是可持续结构复合材料的灵感来源。[6-8]在这些材料中，组件紧密组装成复杂的分层结构，导致出色的机械性能和低重量。[9]例子包括珍珠层的韧性，[10]石鳖牙齿的硬度，[11]和口足类Dactyl虾棒的拉伸强度。[12]这些材料都有一个共同的生物矿化的有机相，具有特殊的断裂韧性的基础上，甲壳素纳米纤维往往嵌入在一个类似丝绸的蛋白质基质。[4，13]尽管有这些理想的性能，但由于甲壳素在大多数有机溶剂中的不溶性，基于甲壳素纳米纤维的人工仿生复合材料难以生产。[14]在这里，我们介绍了一种仿生复合材料从溶液共组装的自组装超细（3 nm）甲壳素纳米纤维在丝基质（图1）。这种轻质（ρ= 1.4 g cm− 3）仿生复合材料具有优异的机械性能，甚至比最硬的组分甲壳素更硬。这些特性来自于在共组装过程中产生的几丁质-丝氢键。由于溶液加工的容易性、材料成分的天然丰富性和生物降解性，这种几丁质-丝生物复合材料可以在天然衍生的塑料以及生物医学装置中找到应用。[15]甲壳素[聚（β-（1，4）-N-乙酰基-D-葡萄糖胺]]是仅次于纤维素的第二大天然多糖。[14]几丁质以有序的结晶纳米纤维形式存在，并且是真菌和酵母中细胞壁、节肢动物的外骨骼和软体动物壳的主要结构组分。[16]甲壳素具有机械稳定性、生物可降解性、无毒和生理惰性。[17]甲壳素有希望用于各种生物医学应用，包括伤口敷料和缝合线，[18]组织工程支架，[14，19]和生物相容性设备。[20]丝蛋白是一种独特的生物聚合物家族，其在结构和生物学特性方面提供了多功能性，可以以多种材料形式表达。[21]蜘蛛和蚕吐出的丝是已知最强韧的天然纤维。[22此外，与常规无机聚合物相比，丝提供了广泛的功能化、加工和生物整合的机会。[24已经将甲壳素和丝混合以产生用于组织工程支架的大直径电纺纳米纤维。[15]由于甲壳素在大多数有机溶剂中不溶性，溶液加工更常见于甲壳素的脱乙酰化形式，壳聚糖。壳聚糖-丝混合物具有差的机械性能，这可能是由于壳聚糖不能结晶成纳米纤维[26]并与丝形成有序的复合结构。[27]壳聚糖不形成纳米纤维，因为它缺乏几丁质的乙酰酰胺基团，该乙酰酰胺基团有助于在几丁质自组装过程中形成氢键。[26]为了克服这些局限性，最近已经创建了具有优异机械性能的壳聚糖-丝层压板来模仿昆虫表皮的微观结构。[28]在这些先前结果的基础上，我们在这里介绍一种基于甲壳素纳米纤维丝生物复合材料的一步溶液，该生物复合材料紧密复制了昆虫表皮有机相的纳米结构，该有机相由嵌入在丝样蛋白质基质中的甲壳素纳米纤维制成。[4，13]为了产生甲壳素-丝生物复合材料，鱿鱼笔β-甲壳素和B的溶液。用六氟异丙醇（HFIP）共溶的桑蚕丝在聚二甲基硅氧烷模具上干燥，得到了具有良好物理机械性能的丝素。
Natural structural materials [1, 2] such as bone, tooth, wood, arthropod cuticle,[3, 4] crustacean exoskeleton,[5] and mollusk shell are inspiration for sustainable structural composites.[6–8] In these materials, the intimate assembly of components into a complex hierarchical structure results in outstanding mechanical properties coupled with low weight.[9] Examples include the toughness of nacre,[10] the hardness of the chiton tooth,[11] and the tensile strength of the Stomatopod Dactyl shrimp club.[12] These materials have in common a biomineralized organic phase with exceptional fracture toughness based on chitin nanofibers often embedded in a silk-like protein matrix.[4, 13] Despite these desirable properties, artificial bioinspired composites based on chitin nanofibers have been difficult to produce due to chitin’s insolubility in most organic solvents.[14] Here, we introduce a biomimetic composite from the solution co-assembly of self-assembled ultrafine (3 nm) chitin nanofibers in a silk matrix (Figure 1). This lightweight (ρ= 1.4 g cm− 3) biomimetic composite has excellent mechanical properties and is even stiffer than chitin, the stiffest component. These properties derive from chitin-silk hydrogen bonding that is created during the co-assembly process. With the ease of solution processing, natural abundance of the material constituents, and biodegradability, this chitin-silk biocomposite may find applications in naturally-derived plastics as well as biomedical devices.[15] Chitin [poly (β-(1, 4)-N-acetyl-D-glucosamine] is the second most abundant natural polysaccharide after cellulose.[14] Chitin occurs as ordered crystalline nanofibers, and is the major structural component of cell walls in fungi and yeast, the exoskeleton of arthropods, and mollusk shells.[16] Chitin is mechanically stable, biodegradable, nontoxic, and physiologically inert.[17] Chitin is promising for a variety of biomedical applications including wound dressing and sutures,[18] tissue engineering scaffolds,[14, 19] and biocompatible devices.[20] Silk proteins are a unique family of biopolymers that offer versatility in structural and biological properties that can be expressed in a multitude of material formats.[21] Silks spun by spiders and silkworms are the strongest and toughest known natural fibers.[22, 23] Additionally, silks offer a wide range of opportunities for functionalization, processing, and biological integration in comparison to conventional inorganic polymers.[24, 25] Chitin and silk have been mixed to produce large diameter electrospun nanofibers for tissue engineering scaffolds.[15] Due to chitin’s insolubility in most organic solvents, solution processing is more common with the deacetylated version of chitin, chitosan. Chitosan-silk mixtures have poor mechanical properties possibly resulting from the inability of chitosan to crystallize into nanofibers [26] and form an ordered composite structure with silk.[27] Chitosan does not form nanofibers because it lacks chitin’s acetylamide groups that contribute to hydrogen bonding during the chitin nanofiber self-assembly process.[26] To overcome these limitations, recently a chitosan-silk laminate with exceptional mechanical properties has been created to mimic the insect cuticle microstructure.[28] Building on these previous results, we introduce here a one-step solution based chitin nanofibersilk biocomposite that closely replicates the nanostructure of the insect cuticle organic phase, which is made of chitin nanofibers embedded in a silk-like protein matrix.[4, 13] To create the chitin-silk biocomposite, solutions of squid pen β-chitin and B. Mori cocoon silk co-dissolved in hexafluoroisopropanol (HFIP) are dried on a polydimethylsiloxane mold to …