Department of Mechanical and Industrial Engineering, College of Engineering and Technology , University of Dar es Salaam , P.O. BOX 35131 , Dar es Salaam , Tanzania.
Biomacromolecules. 2020 Feb 10;21(2):604-612. doi: 10.1021/acs.biomac.9b01342. Epub 2019 Dec 4.
The α-chitin nanofibril is an alternative to nanocellulose as a building-block for strong films and other nanomaterials. The hypothesis of high film strength for films based on mildly treated insect cuticles was tested. Fibrils from the cuticle of (a long-horned bush cricket grasshopper locally known as senene) are disintegrated by a mild process, subsequently characterized by transmission electron microscopy, NMR, Fourier transform infrared spectroscopy, and XRD, and used to prepare strong and transparent films. A mild process (with 20% NaOH treatment for 2 weeks and at room temperature) was used to largely remove the strongly bound protein associated with chitin. The purpose was to reduce chitin degradation. The native structure of chitin was indeed well preserved and close to the native state, as is supported by data for degree of acetylation, molar mass, crystallinity, and crystallite dimensions. The diameter of the smallest chitin fibrils was as small as 3-7 nm (average 6 nm) with lengths larger than or around 1 μm. A stable and well-dispersed colloidal chitin fibril suspension in water was achieved. A nanostructured chitin film prepared by filtration showed high optical transmittance (∼90%) and very high tensile strength (220 MPa). The high tensile strength was attributed to the well-preserved chitin structure, high intrinsic fibril strength, and high colloidal stability of the fibril suspension. Strong, transparent insect chitin films offer interesting alternatives to nanocellulose films because of different resource origins, surface chemistries, and potential antimicrobial properties.
α-壳聚糖纳米原纤维是纳米纤维素的替代品，可用于制造高强度薄膜和其他纳米材料。本研究检验了基于轻度处理昆虫外骨骼的薄膜具有高机械强度的假设。通过温和的方法从 （一种长角蝉科的直翅目昆虫，当地称为 senene）的外骨骼中提取纳米原纤维，然后通过透射电子显微镜、NMR、傅里叶变换红外光谱和 XRD 对其进行表征，并用于制备高强度和透明的薄膜。温和的处理方法（20%的 NaOH 在室温下处理 2 周）主要去除了与壳聚糖结合紧密的蛋白质。目的是减少壳聚糖的降解。事实上，壳聚糖的天然结构得到了很好的保留，接近于天然状态，这一点可以从乙酰化程度、摩尔质量、结晶度和微晶尺寸的数据得到支持。最小壳聚糖原纤维的直径小至 3-7nm（平均 6nm），长度大于或约 1μm。成功获得了在水中稳定且分散良好的壳聚糖原纤维胶体悬浮液。通过过滤制备的纳米结构壳聚糖薄膜具有高透光率（约 90%）和非常高的拉伸强度（220MPa）。高拉伸强度归因于壳聚糖结构得到了很好的保留、原纤维强度高、以及原纤维悬浮液的胶体稳定性高。由于资源来源、表面化学性质和潜在的抗菌性能不同，高强度、透明的昆虫壳聚糖薄膜为纳米纤维素薄膜提供了有趣的替代品。
