TEMPO氧化法制备纳米几丁质晶须粒子的优化及其产品特性表征

Optimization and Characterization of TEMPO-Mediated Oxidization of Nanochitin Whiskers

以虾壳几丁质为原料,利用TEMPO-NaBr-NaClO选择性氧化体系制备羧基化纳米几丁质晶须粒子。测定了反应体系中pH值与NaClO(13%有效氯)含量的变化对几丁质羧基化的影响,研究了生产高羧基含量和小颗粒粒度纳米几丁质晶须的最佳反应条件。利用傅里叶变换红外光谱、透射电子显微镜、动态光散射对制备的负电荷纳米几丁质晶须粒子进行结构表征,测定产品水悬浮液的有效粒径和有效电位;采用电导率法测定负电荷纳米几丁质的羧基含量。实验结果表明:在反应体系B1(pH=10.5,V(NaClO)=15mL)中,制备的负电荷纳米几丁质羧基含量最大,达(3.16±0.23)mmol/g,纳米晶须粒子流体动力学粒径(Z-average)为(113.97±2.29)nm,Zeta电位为(-38.73±4.49)mV;在反应体系B0(pH=10.5,V(NaClO)=18mL)中,制备的NC-晶须的羧基含量、粒子Z-average和Zeta电位分别为(3.00±0.41)mmol/g、(106.13±0.38)nm和(-41.41±6.83)mV。上述两种条件制备的纳米几丁质晶须粒子羧基含量和Zeta电位没有显著差异,但B0晶须粒子有效粒径最小。由于纳米材料的小尺寸效应是影响纳米材料生物活性的关键因素,因此制备高生物活性的纳米几丁质晶须的最佳条件是B0,即制备条件为pH=10.5,V(NaClO)=18mL(13%)。

Carboxylate nanochitin（NC-）whiskers were prepared from shrimp chitin by TEMPO-NaBr-NaClO selective oxidation system.The optimal condition for production of small particles size with high carboxyl content of NC-were investigated by adjusting the pH value and dosage of NaClO（13% available chlorine）in the TEMPO-mediated oxidization system.The resulted NC-whiskers were qualified by Fourier transform infrared spectrometry;the morphology,effective size and size distribution,zeta potential,and carboxyl content of NC-whiskers were examined by transmission electron microscopy,dynamic light scattering method,and conductometry,respectively.The results showed that NC-whiskers synthesized in reaction system B1（pH=10.5,V（NaClO）=15 mL in the system）had a highest carboxyl group of（3.16±0.23）mmol/g with hydrodynamic diameter（Z-average）of（113.97±2.29）nm and（-38.73±4.49）mV for zeta potential,while the carboxyl content,particle size and zeta potential of the resulted NC^-whiskers synthesized in reaction system B0（pH=10.5,V（NaClO）=18 mL）were（3.00±0.41）mmol/g,（106.13±0.38）nm and（-41.41±6.83）mV respectively.The particle size was significantly decreased with an increase of NaClO in the reaction system at pH 10.5 but there was no significant difference in carboxyl content and zeta potential.Therefore,the optimal condition to produce NC-whisker with a high biological activity is the treatment B0 due to small-size effect of nanomaterials,which was corresponding to the pH=10.5 and V（NaClO）=18 mL in the reaction system.