Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Jiangsu Key Lab of Biomass-based Green Fuel & Chemicals, College of Chemical Engineering , Nanjing Forestry University , Nanjing 210037 , China.
Department of Biomaterials Science, Graduate School of Agricultural and Life Sciences , The University of Tokyo , Tokyo 113-8657 , Japan.
J Agric Food Chem. 2018 Oct 31;66(43):11372-11379. doi: 10.1021/acs.jafc.8b02899. Epub 2018 Oct 22.
Different from single charged or uncharged nanocrystals, amphoteric chitin nanocrystals (A-ChNCs) with both amine and carboxylate groups prepared with 2,2,6,6-tetramethylpiperidine-1-oxy-radical (TEMPO)-mediated oxidation and partial deacetylation were individually nanodispersed by sonicating in water at pH 3 and pH 11. The effects of the amount of NaClO added in TEMPO-oxidation, deacetylation time, and sequence of the two treatments on the weight recovery ratios of the A-ChNCs were investigated. The A-ChNCs prepared under optimum conditions had an average length of ∼544 nm and an average width of ∼10 nm. The A-ChNCs nanodispersed in water at pH 3 and pH 11 had absolute ζ-potentials of >30 mV; however, in neutral water, they formed aggregations, which were nanodispersed again when pH was adjusted to 3 or 11, showing pH sensitivity. Hydrogels of A-ChNC were prepared by adding saturated NaCl solution and adsorbed both anionic and cationic dyes. Freeze-dried A-ChNC aerogels had three-dimensional network structures containing abundant pores.
与单电荷或不带电荷的纳米晶体不同，两性壳聚糖纳米晶体（A-ChNCs）同时具有胺基和羧酸盐基团，由 2,2,6,6-四甲基哌啶-1-氧基自由基（TEMPO）介导的氧化和部分脱乙酰化制备而成，在 pH 值为 3 和 pH 值为 11 的水中通过超声分散实现个体纳米分散。研究了添加的 NaClO 量、脱乙酰化时间以及这两种处理的顺序对 A-ChNCs 重量回收率的影响。在最佳条件下制备的 A-ChNCs 的平均长度约为 544nm，平均宽度约为 10nm。在 pH 值为 3 和 pH 值为 11 的水中分散的 A-ChNCs 的绝对 ζ-电位大于 30mV；然而，在中性水中，它们会形成聚集体，当 pH 值调节为 3 或 11 时，又会再次分散，表现出 pH 敏感性。通过添加饱和 NaCl 溶液制备了 A-ChNC 的水凝胶，可吸附阴离子和阳离子染料。冷冻干燥的 A-ChNC 气凝胶具有包含丰富孔的三维网络结构。
