含酚基羧甲基纤维素的合成及单分散微胶囊的制备

Synthesis of Carboxymethylcellulose with Phenol Moieties for Preparation of Monodisperse Microcapsules

为了实现可程序控制的活性物质的释放,制备了单分散的羧甲基纤维素(CMC)衍生物微胶囊。采用1-乙基-(3-二甲基氨基丙基)碳二亚胺(EDC)和N-羟基琥珀酰亚胺(NHS)作为偶合剂,在CMC的大分子链上引入酚基,合成了含酚基羧甲基纤维素(Ph-CMC)。产物的紫外吸收光谱证实,在275 nm处出现苯环的特征吸收峰,根据吸光度值计算,每100个CMC结构单元中酚基数量为30～50个。Ph-CMC溶液具备牛顿流体的特征,且随着Ph-CMC相对分子质量或溶液浓度的增加,流体切应力及黏度呈上升趋势。采用自行研制的同轴汇聚微流体装置,以含辣根过氧化物酶的Ph-CMC水溶液为内流体,含双氧水和卵磷脂的液体石蜡为外流体,制备了半径为150～200μm,且偏差系数≤3%的单分散Ph-CMC微胶囊。

Monodisperse microcapsules of carboxymethylcellulose （CMC） derivatives were prepared, with the final aim to achieve programmable release of active substances. Using 1-ethyl- （3-3-dimethylaminopropyl）carbodiimide hydrochloride （EDC） and N-hydroxysuccinmide （NHS） as coupling agents, CMC with weight-average molecular weight 200 000, 250 000 and 300 000 was grafted with 4-hydroxybenzylamine to synthesize CMC with phenol moieties （Ph-CMC）, abbreviated as Ph-CMC20, Ph-CMC25, and Ph-CMC30, respectively. UV absorbance spectra of Ph-CMC presented a benzene characteristic absorption peak at 275 nm, from which graft density of phenols in CMC was calculated. And the results showed that Ph-CMC with different molecular weight contained 30～50 phenols per 100 repeat units of CMC. The aqueous Ph-CMC solution showed Newtonian fluid characteristics, and the shear stresses and viscosities increased with the increase of Ph-CMC molecular weight or concentration. An axisymmetic flow-focusing device was self-designed, through which the Ph-CMC solution with horseradish peroxidase was extruded into a coflowing immiscible stream of liquid paraffin containing H202 and lecithin. Ph-CMC microcapsules with the average radius of 150～200 μm presented high monodispersity with low coefficients of variation （≤ 3 %）.