School of Chemical Engineering, University of Campinas, UNICAMP, P.O. Box 6066, 13083-970 Campinas-SP, Brazil.
Langmuir. 2010 Jun 1;26(11):8953-8. doi: 10.1021/la904741h.
Chitosan/silk fibroin multilayer thin films were assembled using layer-by-layer deposition. The resultant multilayer films contained nanofibers aligned parallel to the dipping direction. Fiber deposition and orientation was enabled uniquely by a judicious choice of solvent and drying conditions and layer-by-layer assembly with chitosan. The deposition of oriented nanofibers was found to be the result of a unique combination of layer-by-layer and Langmuir-Blodgett type processing. Fiber orientation was confirmed by fast Fourier transform (FFT) analysis of optical micrographs and atomic force microscopy (AFM). Bidirectional fiber alignment was realized by rotating the substrate between multilayer deposition steps. Infrared spectroscopy revealed that the silk fibroin adopted the silk II secondary structure in the deposited films. We anticipate that these anisotropic films are able to combine the biocompatibility of a natural polymer system with the mechanical strength of SF, two properties useful in many biological applications including scaffolds suitable for guiding cell attachment and spreading.
壳聚糖/丝素蛋白多层薄膜是通过层层自组装技术制备的。所得的多层薄膜中含有沿浸渍方向平行排列的纳米纤维。通过选择合适的溶剂和干燥条件以及与壳聚糖的层层组装，可以实现纤维的沉积和取向。定向纳米纤维的沉积是层状和 Langmuir-Blodgett 型加工的独特组合的结果。纤维取向通过光学显微镜和原子力显微镜（AFM）的快速傅里叶变换（FFT）分析得到证实。通过在多层沉积步骤之间旋转基底，可以实现双向纤维取向。红外光谱表明，丝素蛋白在沉积的薄膜中采用了丝素 II 二级结构。我们预计这些各向异性的薄膜能够将天然聚合物体系的生物相容性与 SF 的机械强度结合起来，这两种特性在许多生物应用中都很有用，包括适合引导细胞附着和扩散的支架。
