Abstract：
Nisin is a bacteriocin produced by Gram-positive lactic acid bacterium,Lactococcus lactisand currently recognized in the Generally Recognızed as Safe (GRAS) category due to its non-toxicity. Herein, nisin has been grafted to chitosan structure to obtain natural bio-active films with enhanced antibacterial activity. Grafting was performed using ethyl ester lysine diisocyanate and dimer fatty acid-based diisocyanate (DDI); two different close to fully bio-based diisocyanates and Disuccinimidyl suberate; a homo-bifunctional molecule acting as a crosslinker between amino groups. The grafting process allowed the chemical immobilization of nisin to chitosan structure. Physicochemical characterization studies showed the successful grafting of nisin. The antibacterial activity againstStaphylococcus aureuswas evident for all nisin modified chitosan films and best pronounced when DDI was used as a crosslinker with a maximum zone of inhibition of ∼13 mm. All nisin grafted chitosan films were cytocompatible and the cell viability of L929 fibroblasts were >80% pointing out the non-toxic structure. Considering the results of the presented study, bio-based diisocyanates and homo-bifunctional crosslinkers are effective molecules in synthesis of nisin grafted chitosan structures and the new chitosan based antibacterial biopolymers obtained after nisin modification come forward as promising non-toxic and bioactive candidates to be applied in medical devices, implants, and various food coating products.
摘要：
Nisin是由革兰氏阳性乳酸菌产生的细菌素，乳酸乳球菌由于其无毒性而目前被认为属于GRAS类别。在这里，已将乳酸链球菌素接枝到壳聚糖结构上，以获得具有增强抗菌活性的天然生物活性膜。使用乙基酯赖氨酸二异氰酸酯（EELDI）和基于二聚体脂肪酸的二异氰酸酯（DDI）进行接枝；两种不同的接近完全生物基二异氰酸酯和辛二酸二琥珀酰亚胺酯（DSS）；同双官能分子充当氨基之间的交联剂。接枝过程允许将乳链菌肽化学固定到壳聚糖结构上。物理化学表征研究表明乳酸链球菌素的成功接枝。对于所有乳链菌肽改性的壳聚糖膜，对金黄色葡萄球菌的抗菌活性都很明显，并且当DDI用作交联剂时，其最大抑制区为13mm时，效果最好。所有乳酸链球菌素接枝的壳聚糖膜均具有细胞相容性，L929成纤维细胞的细胞活力为80％，表明其无毒结构。考虑到本研究的结果，生物基二异氰酸酯和同双功能交联剂是合成乳酸链球菌素接枝壳聚糖结构的有效分子，乳酸链球菌素改性后获得的新型壳聚糖抗菌生物聚合物成为有前途的无毒和生物活性候选物，可用于医疗器械，植入物,和各种食品涂料产品。
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