摘要
本研究以TEMPO氧化纳米纤维素(TOCNF)为唯一载体和分散剂,AgNO3溶液为银源,通过水热法合成纳米银颗粒(AgNPs),制备纳米银颗粒/纳米纤维素复合材料(Ag-CNF),并探究了TOCNF含量和A
近年来,人们对病毒、细菌的防护意识逐渐提高,而银(Ag)在抗菌方面的应用具有悠久的历史。研究人员发现纳米银材料具有比A
AgNPs最常见的制备方法是基于银盐的化学还原法,包括有机或无机化学还原
纳米纤维素表面丰富的基团使其具有良好的分散性,可广泛地用于碳纳米
TEMPO氧化是改性纳米纤维素最常见的方法之一,由于空间位阻效应,只有C6位上的羟基发生氧
本研究以漂白桉木浆为原料,利用TEMPO/NaClO/NaBr碱性氧化体系预处理和高压均质,制备TOCNF。以TOCNF为唯一还原剂和分散剂,AgNO3溶液为银源,水热合成AgNPs,并制备纳米银颗粒/纳米纤维素复合材料(Ag-CNF)。对Ag-CNF的理化性质进行表征和分析,并研究TOCNF含量和A
漂白桉木浆(浆板),购自华邦古楼新材料有限公司;2,2,6,6-四甲基哌啶氧化物(TEMPO,质量分数98%),购自Sigma-Aldrich化学试剂公司;溴化钠(NaBr,分析纯)、溴化钾(KBr,光谱纯),购自天津科密欧有限公司;次氯酸钠(NaClO,质量分数10%),购自广州化学试剂厂;氢氧化钠(NaOH,分析纯,固体),购自天津市福晨化学试剂厂;硝酸银(AgNO3,分析纯),购自广州市东征化玻仪器有限公司;大肠杆菌(E. coli,ATCC 43894)、金黄色葡萄球菌(S. aureus,ATCC 25923)、LB肉汤(粉末)、技术琼脂粉(粉末)、PBS缓冲液(粉末),购自广东环凯微生物科技公司。
称取20 g绝干桉木浆至3 L的三口烧瓶中,加入去离子水将浆料分散均匀,依次加入0.1 mmol/g TEMPO、1 mmol/g NaBr和10 mmol/g NaClO(用量均为相对于绝干桉木浆质量),补充去离子水确保反应体系的固含量为1%。不断滴加1 mmol/L NaOH溶液,控制反应体系pH值=10~10.5,在30 min内pH值变化<0.1时,加入5 mL无水乙醇终止反应,用去离子水多次洗涤浆料至洗液pH值呈中性。使用高压微射流纳米分散机(Nano DeBEE,美国BEE国际股份有限公司)将浆料重复均质8次,获得TOCNF。
本研究以TOCNF为载体和分散剂,在碱性条件下通过水热法还原纳米银颗粒(AgNPs),并制备纳米银颗粒/纳米纤维素复合材料(Ag-CNF),其制备过程如
图1 Ag-CNF的制备示意图
Fig. 1 Schematic diagram of Ag-CNF
通过TEMPO氧化引入的羧基使TOCNF具有良好的分散效果,加入的A
为了相对准确的衡量Ag-CNF中AgNPs的浓度,使用过量强还原剂NaBH4还原A
使用X射线光电子能谱仪(XPS,K-Alpha, Thermo Scientific)对TOCNF和Ag-CNF进行测试。将测试样品制备成薄膜,在激发源为Al Kα射线(hv=1486.6 eV)的条件下对样品进行全谱扫描和精细谱扫描。
使用场发射扫描电子显微镜(FESEM,Merline,德国蔡司公司)和联用X-MaxN20能谱仪(EDS, Oxford, UK)对CNF和Ag-CNF薄膜进行表面形貌观察和表面化学元素组成分析。
使用透射电子显微镜(TEM, FEI Talos F200x,Thermo Scientific)对分散的TOCNF和Ag-CNF的微观形貌进行观察。
由于量子尺寸效应,AgNPs在紫外-可见光范围内能够形成特征吸收峰。AgNO3和Ag-CNF吸收光谱如
图2 AgNO3和Ag-CNF的UV-Vis谱图
Fig. 2 UV-Vis spectra of AgNO3 solution and Ag-CNF
TOCNF在该体系中作为载体和分散剂,会影响单质Ag的聚集状态从而影响AgNPs的形成。根据AgNPs形态和尺寸的不同,其吸收峰的位置和形状也会出现差
图3 不同TOCNF含量、A
Fig. 3 Photos of Ag-CNF prepared under different content of TOCNF and concentrations of A
图4 不同TOCNF含量制备的Ag-CNF的UV-Vis分析结果
Fig. 4 UV-Visanalysis results of Ag-CNF prepared with different TOCNF contents
不同A
由于UV-Vis的吸光值最大为4.0,在测试A
图5 不同A
Fig. 5 UV-Vis analysis results of Ag-CNF prepared with different A
使用Avantage软件对XPS数据进行处理和分析,电荷校正以C 1s=284.8 eV结合能为标准。
图6 TOCNF和Ag-CNF的XPS谱图
Fig. 6 XPS spectra of TOCNF and Ag-CNF
在分析Ag元素的价态时,通常需要结合Ag元素的精细谱图和俄歇谱图进行分析。
图7 TOCNF、Ag-CNF和Ag-CNF薄膜的FESEM图
Fig. 7 FESEM images of TOCNF, Ag-CNF colloids, and Ag-CNF film
从
使用TEM观察Ag-CNF中AgNPs的高分辨率形貌,如
图8 Ag-CNF中AgNPs的TEM图和衍射图
Fig. 8 TEM images and diffraction image of AgNPs in Ag-CNF
注 (a)~(c)为AgNPs的TEM图;(d)为AgNPs的衍射图。
对AgNPs的粒径进行统计,结果如
图9 Ag-CNF中的AgNPs的粒径统计
Fig. 9 Particle size statistics of AgNPs in Ag-CNF
使用A
图10 TOCNF和不同稀释倍数的Ag-CNF对E. coli和S. aureus的抗菌表现
Fig. 10 Antibacterial performance of TOCNF and different dilutions of Ag-CNF colloids against E. coli and S. aureus
注: (a)~(e)为E. coli抗菌;(f)~(j)为S. aureus抗菌。
GB/T 38453——2020规定,抑菌圈直径>1 mm时,表明样品具有抗菌性能,因此,Ag-CNF对E. coli和S. aureus表现出良好的抗菌性能。由
本研究在聚丙烯酰胺(PAM)水凝胶的基础上引入Ag-CNF,制备抗菌水凝胶,称取0.1 g水凝胶样品,采用接触培养法表征其抗菌性能,如
图11 抗菌水凝胶的抗菌效果
Fig. 11 Antibacterial effect of antibacterial hydrogels
本研究以TEMPO氧化纳米纤维素(TOCNF)为载体和分散剂,在碱性条件下通过水热法制备纳米银颗粒/纳米纤维素复合材料(Ag-CNF),整个过程中无需加入额外的还原剂,是一种绿色合成方法。
3.1 结合X射线衍射光谱中Ag 3d的结合能和俄歇参数及TEM图像,综合验证了纳米银颗粒(AgNPs)的合成。在一定的A
3.2 随着A
3.3 Ag-CNF复合材料中的AgNPs平均粒径为22.3 nm,且分散均匀,无明显大颗粒聚集现象。
3.4 制备的Ag-CNF对大肠杆菌和金黄色葡萄球菌分别具有直径为2.70和3.50 mm的抑菌圈,添加Ag-CNF的水凝胶也保持着优秀的抗菌性能,在抗菌生物材料的开发中具有很大的潜力。
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