Abstract Biodegradable, non-toxic and transparent poly (l-lactic acid) (PLLA) biopolymer is modified in order to obtain an improved material with antibacterial properties for its use as active packaging of food. For this, PLLA films were endowed with the bactericidal effect of ZnO nanoparticles by internal blending and the bacteria contact-killing properties of the biopolymer chitosan (CHI) by superficial modification. Surface functionalization with CHI was carried out by covalent or electrostatic functionalization which were comparatively analyzed in terms of yield and stability. Additionally, the effect of employed CHI concentration and molecular weight was also studied for both modification methods. Modified films were characterized by confocal fluorescence microscopy, contact angle measurements, UV–Vis spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and electrostatic force microscopy. The antibacterial properties of each modification on PLLA were studied against Escherichia coli, showing the greater microbial death after covalent functionalization with CHI. Moreover, stability of modified films was studied in enzymatic and non-enzymatic medium and it was improved by chemical crosslinking with the natural molecule genipin. The valuable properties of PLLA, as well as the derived antibacterial properties of the incorporation of ZnO nanoparticles and CHI, make prepared films highly attractive candidates for the innovative packaging industry.

中文翻译：

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抗菌壳聚糖静电/共价涂层到可生物降解的聚（-乳酸）上

摘要 对可生物降解、无毒且透明的聚（l-乳酸）（PLLA）生物聚合物进行改性，以获得具有抗菌性能的改进材料，用作食品的活性包装。为此，PLLA 薄膜通过内部混合赋予了 ZnO 纳米粒子的杀菌作用，通过表面改性赋予了生物聚合物壳聚糖 (CHI) 的细菌接触杀灭特性。CHI的表面功能化通过共价或静电功能化进行，在产率和稳定性方面进行了比较分析。此外，还研究了两种改性方法所采用的 CHI 浓度和分子量的影响。通过共聚焦荧光显微镜、接触角测量、UV-Vis 光谱、X 射线光电子能谱、原子力显微镜和静电力显微镜。研究了 PLLA 上每个修饰对大肠杆菌的抗菌特性，显示与 CHI 共价官能化后微生物死亡更多。此外，在酶促和非酶促介质中研究了改性薄膜的稳定性，并通过与天然分子京尼平的化学交联来提高稳定性。PLLA 的宝贵特性，以及结合 ZnO 纳米颗粒和 CHI 的衍生抗菌特性，使制备的薄膜成为创新包装行业极具吸引力的候选者。显示与 CHI 共价官能化后微生物死亡更多。此外，在酶促和非酶促介质中研究了改性薄膜的稳定性，并通过与天然分子京尼平的化学交联来提高稳定性。PLLA 的宝贵特性，以及结合 ZnO 纳米颗粒和 CHI 的衍生抗菌特性，使制备的薄膜成为创新包装行业极具吸引力的候选者。显示与 CHI 共价官能化后微生物死亡更多。此外，在酶促和非酶促介质中研究了改性薄膜的稳定性，并通过与天然分子京尼平的化学交联来提高稳定性。PLLA 的宝贵特性，以及结合 ZnO 纳米颗粒和 CHI 的衍生抗菌特性，使制备的薄膜成为创新包装行业极具吸引力的候选者。