Bacterial Cellulose Nanofibers Modified with Quaternary Ammonium Salts for Antimicrobial Applications
Bacterial Cellulose Nanofibers Modified with Quaternary Ammonium Salts for Antimicrobial Applications
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DOI：
10.1021/acsanm.3c00616
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发表时间：
2023-03
影响因子：
5.9
通讯作者：
H. Kono;Yoichiro Sogame;Uugan-Erdene Purevdorj;M. Ogata;K. Tajima
中科院分区：
文献类型：
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作者：
H. Kono;Yoichiro Sogame;Uugan-Erdene Purevdorj;M. Ogata;K. Tajima
纳米纤维化细菌纤维素（NFBC）是一种可回收、可生物降解、无毒的生物聚合物，其纤维比其他由木浆制备的纤维素纳米纤维长得多。NFBC是一种很有前途的材料，可以用作食品和制药工业的添加剂，也可以用作纤维增强纳米复合树脂的纳米填充剂；然而，它很容易被微生物降解，因此不能长期使用。在本研究中，NFBC通过2,3-环氧丙基三甲基氯化铵（EPTMAC）的碱性水溶液改性而具有抗菌性能。利用固体核磁共振、红外光谱和x射线衍射对改性后的NFBC进行了详细的结构分析，结果表明，每根纤维仅在表层上共轭了季铵型EPTMAC基团，制备过程中EPTMAC的加入量决定了阳离子基的摩尔取代度（MS）。此外，由于纳米纤维之间的静电斥力，增加改性NFBC的质谱会导致表面带正电荷，从而增加纳米纤维分散的透明度。尽管存在这些差异，但改性纤维的纤维形态和晶体结构与原始NFBC几乎相同，这表明EPTMAC选择性地与NFBC的表面羟基发生反应。此外，细菌细胞培养实验显示，改性的纳米纤维对肺炎克雷伯菌（一种革兰氏阴性细菌）具有抗菌作用，这很可能是因为改性的NFBC表面带正电。因此，季铵盐改性的NFBC是一种既具有纳米纤维特性又具有抗菌性能的功能性纳米纤维，可用于纤维增强纳米填料、水性涂料和极性树脂的絮凝剂。
Nanofibrillated bacterial cellulose (NFBC) is a recyclable, biodegradable, and nontoxic biopolymer whose fibers are much longer than other cellulose nanofibers prepared from wood pulp. NFBC is a promising material for use as an additive in food and pharmaceutical industries and as a nanofiller in fiber-reinforced nanocomposite resins; however, it is easily microbially degraded and, consequently, cannot be used in long-term applications. In this study, NFBC was endowed with antimicrobial properties through modification by an aqueous alkaline solution of 2,3-epoxypropyltrimethylammonium chloride (EPTMAC). The structure of the modified NFBC was analyzed in detail using solid-state NMR and infrared spectroscopy, as well as X-ray diffractometry, which revealed that only the surface layer of each fiber had been conjugated with quaternary ammonium EPTMAC groups, with the amount of EPTMAC added during preparation determining the degree of molar substitution (MS) of the cationic groups. In addition, increasing the MS of the modified NFBC resulted in a positive surface charge that led to an increase in the transparency of the nanofiber dispersion owing to electrostatic repulsion between nanofibers. Despite these differences, the fiber morphologies and crystal structures of the modified fibers were almost identical to those of pristine NFBC, suggesting that EPTMAC selectively reacts with the surface hydroxyl groups of NFBC. In addition, bacterial cell culture experiments revealed that the modified nanofibers are antimicrobial againstKlebsiella pneumoniae, a Gram-negative bacterium, most likely because the surface of the modified NFBC is positively charged. Therefore, the quaternary-ammonium-salt-modified NFBC is a functional nanofiber endowed with both nanofiber features and antimicrobial properties and can possibly be used in fiber-reinforced nanofillers and as a flocculant for water-based paints and polar resins.