Fan Yimin, Saito Tsuguyuki, Isogai Akira
Department of Biomaterials Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
Biomacromolecules. 2008 Jan;9(1):192-8. doi: 10.1021/bm700966g. Epub 2007 Dec 27.
Chitin nanocrystals dispersed in water were successfully prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) mediated oxidation of alpha-chitin in water at pH 10 under specific conditions, followed by ultrasonic treatment. When the amount of NaClO added as co-oxidant in the oxidation was 5.0 mmol/g of chitin, the weight percentage of the water-insoluble fraction in the TEMPO-oxidized chitin was 90%, and its carboxylate content reached 0.48 mmol/g. Since the TEMPO-oxidized chitin thus prepared had a crystallinity as high as that of the original alpha-chitin, the C6 carboxylate groups formed by TEMPO-mediated oxidation can be regarded as being present only on the chitin crystallite surfaces. No N-deacetylation occurred on the TEMPO-oxidized chitins. When the TEMPO-oxidized chitin was subjected to ultrasonic treatment in water, mostly individualized chitin nanocrystals were obtained, and the average nanocrystal length and width were 340 and 8 nm, respectively.
在特定条件下，于pH 10的水中，通过2,2,6,6-四甲基哌啶-1-氧基自由基（TEMPO）介导的α-甲壳素氧化反应，随后进行超声处理，成功制备了分散于水中的甲壳素纳米晶体。当氧化反应中作为共氧化剂添加的NaClO量为5.0 mmol/g甲壳素时，TEMPO氧化甲壳素中不溶于水部分的重量百分比为90%，其羧酸盐含量达到0.48 mmol/g。由于如此制备的TEMPO氧化甲壳素具有与原始α-甲壳素一样高的结晶度，TEMPO介导氧化形成的C6羧酸盐基团可被视为仅存在于甲壳素微晶表面。TEMPO氧化甲壳素上未发生N-脱乙酰化反应。当TEMPO氧化甲壳素在水中进行超声处理时，大多获得了个体化的甲壳素纳米晶体，且纳米晶体的平均长度和宽度分别为340和8 nm。
