Department of Chemistry, Marquette University, P.O. Box 1881, Milwaukee, WI 53201, USA.
Department of Chemistry, Marquette University, P.O. Box 1881, Milwaukee, WI 53201, USA.
Carbohydr Polym. 2016 Oct 20;151:1269-1276. doi: 10.1016/j.carbpol.2016.06.021. Epub 2016 Jun 6.
Novel composites between cellulose (CEL) and keratin (KER) from three different sources (wool, hair and chicken feather) were successfully synthesized in a simple one-step process in which butylmethylimidazolium chloride (BMIm(+)Cl(-)), an ionic liquid, was used as the sole solvent. The method is green and recyclable because [BMIm(+)Cl(-)] used was recovered for reuse. Spectroscopy (FTIR, XRD) and imaging (SEM) results confirm that CEL and KER remain chemically intact and homogeneously distributed in the composites. KER retains some of its secondary structure in the composites. Interestingly, the minor differences in the structure of KER in wool, hair and feather produced pronounced differences in the conformation of their corresponding composites with wool has the highest α-helix content and feather has the lowest content. These results correlate well with mechanical and antimicrobial properties of the composites. Specifically, adding CEL into KER substantially improves mechanical strength of [CEL+KER] composites made from all three different sources, wool, hair and chicken feathers i.e., [CEL+wool], [CEL+hair] and [CEL+feather]. Since mechanical strength is due to CEL, and CEL has only random structure, [CEL+feather] has, expectedly, the strongest mechanical property because feather has the lowest content of α-helix. Conversely, [CEL+wool] composite has the weakest mechanical strength because wool has the highest α-helix content. All three composites exhibit antibacterial activity against methicillin resistant Staphylococcus aureus (MRSA). The antibacterial property is due not to CEL but to the protein and strongly depends on the type of the keratin, namely, the bactericidal effect is strongest for feather and weakest for wool. These results together with our previous finding that [CEL+KER] composites can control release of drug such as ciprofloxacin clearly indicate that these composites can potentially be used as wound dressing.
新型纤维素（CEL）和角蛋白（KER）复合材料由三种不同来源（羊毛、头发和鸡毛）通过简单的一步法成功合成，其中离子液体丁基甲基咪唑氯（BMIm（+）Cl（-））被用作唯一溶剂。该方法绿色且可回收，因为[BMIm（+）Cl（-）]可回收再利用。光谱（FTIR、XRD）和成像（SEM）结果证实，CEL 和 KER 在复合材料中保持化学完整性和均匀分布。KER 在复合材料中保留了部分二级结构。有趣的是，羊毛、头发和羽毛中 KER 结构的微小差异导致其相应复合材料的构象存在明显差异，其中羊毛的α-螺旋含量最高，羽毛的含量最低。这些结果与复合材料的机械和抗菌性能密切相关。具体而言，将 CEL 添加到 KER 中可显著提高由三种不同来源（羊毛、头发和鸡毛）制成的[CEL+KER]复合材料的机械强度，即[CEL+羊毛]、[CEL+头发]和[CEL+羽毛]。由于机械强度取决于 CEL，而 CEL 仅具有无规结构，因此[CEL+羽毛]复合材料具有预期的最强机械性能，因为羽毛的α-螺旋含量最低。相反，[CEL+羊毛]复合材料的机械强度最弱，因为羊毛的α-螺旋含量最高。所有三种复合材料均对耐甲氧西林金黄色葡萄球菌（MRSA）表现出抗菌活性。抗菌性能不是由 CEL 引起的，而是由蛋白质引起的，并且强烈依赖于角蛋白的类型，即羽毛的杀菌效果最强，羊毛的效果最弱。这些结果与我们之前发现的[CEL+KER]复合材料可以控制环丙沙星等药物的释放清楚地表明，这些复合材料可能具有作为伤口敷料的潜力。
