Vilela Carla, Moreirinha Catarina, Domingues Eddy M, Figueiredo Filipe M L, Almeida Adelaide, Freire Carmen S R
Department of Chemistry, CICECO-Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal.
Department of Materials and Ceramic Engineering, CICECO-Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal.
Nanomaterials (Basel). 2019 Jul 6;9(7):980. doi: 10.3390/nano9070980.
Bacterial nanocellulose (BNC) is becoming an important substrate for engineering multifunctional nanomaterials with singular and tunable properties for application in several domains. Here, antimicrobial conductive nanocomposites composed of poly(sulfobetaine methacrylate) (PSBMA) and BNC were fabricated as freestanding films for application in food packaging. The nanocomposite films were prepared through the one-pot polymerization of sulfobetaine methacrylate (SBMA) inside the BNC nanofibrous network and in the presence of poly(ethylene glycol) diacrylate as cross-linking agent. The ensuing films are macroscopically homogeneous, more transparent than pristine BNC, and present thermal stability up to 265 °C in a nitrogen atmosphere. Furthermore, the films have good mechanical performance (Young's modulus ≥ 3.1 GPa), high water-uptake capacity (450-559%) and UV-blocking properties. The zwitterion film with 62 wt.% cross-linked PSBMA showed bactericidal activity against (4.3-log CFU mL reduction) and (1.1-log CFU mL reduction), and proton conductivity ranging between 1.5 × 10 mS cm (40 °C, 60% relative humidity (RH)) and 1.5 mS cm (94 °C, 98% RH). Considering the current set of properties, PSBMA/BNC nanocomposites disclose potential as films for active food packaging, due to their UV-barrier properties, moisture scavenging ability, and antimicrobial activity towards pathogenic microorganisms responsible for food spoilage and foodborne illness; and also for intelligent food packaging, due to the proton motion relevant for protonic-conduction humidity sensors that monitor food humidity levels.
细菌纳米纤维素（BNC）正成为一种重要的基质，用于制造具有独特且可调节性能的多功能纳米材料，以应用于多个领域。在此，由聚（甲基丙烯酸磺酸甜菜碱）（PSBMA）和BNC组成的抗菌导电纳米复合材料被制成独立的薄膜，用于食品包装。通过在BNC纳米纤维网络内部，在聚乙二醇二丙烯酸酯作为交联剂存在的情况下，对甲基丙烯酸磺酸甜菜碱（SBMA）进行一锅法聚合来制备纳米复合薄膜。所得薄膜在宏观上是均匀的，比原始BNC更透明，并且在氮气气氛中具有高达265℃的热稳定性。此外，这些薄膜具有良好的机械性能（杨氏模量≥3.1 GPa）、高吸水能力（450 - 559%）和紫外线阻隔性能。含有62 wt.%交联PSBMA的两性离子薄膜对（减少4.3个对数CFU/mL）和（减少1.1个对数CFU/mL）表现出杀菌活性，质子传导率在1.5×10 mS/cm（40℃，60%相对湿度（RH））和1.5 mS/cm（94℃，98%RH）之间。考虑到当前的一系列性能，PSBMA/BNC纳米复合材料因其紫外线阻隔性能、吸湿能力以及对导致食品变质和食源性疾病的致病微生物的抗菌活性，而展现出作为活性食品包装薄膜的潜力；同时也因其与监测食品湿度水平的质子传导湿度传感器相关的质子运动，而具有用于智能食品包装的潜力。
