State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China.
State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China.
Int J Biol Macromol. 2021 May 1;178:527-535. doi: 10.1016/j.ijbiomac.2021.02.128. Epub 2021 Mar 1.
Recently, cellulose-based stimuli-responsive nanomaterials have received significant attention because of its natural source and biocompatibility. In this study, cellulose-graft-poly(nisopropylacrylamide)-co-2-methyl-acrylic acid 2-carbazol-9-yl-ethyl ester (cellulose-g-(PNIPAAm&PCz)) block polymers were successfully synthesized by homogeneous atom transfer radical polymerization (ATRP) in LiCl/N,N-dimethylacetamide (DMAc) dissolution system. The block polymers showed different properties due to the different PCz content. The block polymer with low PCz content (cellulose-g-(PNIPAAm&PCz)1) was dispersed in water at 25 °C and self-assembled into micelles at 37 °C. On the other hand, the block polymer with high PCz content (cellulose-g-(PNIPAAm&PCz)2) was dissolved in DMF, THF, DMSO firstly, and dialyzed at 25 °C, 37 °C and 60 °C respectively to obtain the micelles. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) indicated that the distribution range of micelles formed by cellulose-g-(PNIPAAm&PCz)1 was narrower than cellulose-g-(PNIPAAm&PCz)2. And the sizes of the micelles formed by cellulose-g-(PNIPAAm&PCz)2 had little difference under different solvents, but became bigger with the temperature increased. The micelles displayed thermo-enhanced fluorescence due to the thermal-driven chain dehydration of the grafted PNIPAAm brushes, which is contrary to the decrease of the fluorescence of the monomer when the temperature increased. The results provided a potential for the application of cellulose-based stimuli-responsive micelles in the field of drug delivery and fluorescent probes.
最近，基于纤维素的刺激响应纳米材料因其天然来源和生物相容性而受到广泛关注。在这项研究中，通过均相原子转移自由基聚合（ATRP）在 LiCl/N，N-二甲基乙酰胺（DMAc）溶解体系中成功合成了纤维素接枝聚（N-异丙基丙烯酰胺）-共-2-甲基-丙烯酸 2-咔唑-9-基-乙基酯（cellulose-g-（PNIPAAm&PCz））嵌段聚合物。由于 PCz 含量不同，嵌段聚合物表现出不同的性质。低 PCz 含量的嵌段聚合物（cellulose-g-（PNIPAAm&PCz）1）在 25°C 时分散在水中，并在 37°C 时自组装成胶束。另一方面，高 PCz 含量的嵌段聚合物（cellulose-g-（PNIPAAm&PCz）2）首先溶解在 DMF、THF、DMSO 中，然后分别在 25°C、37°C 和 60°C 下透析，以获得胶束。透射电子显微镜（TEM）和动态光散射（DLS）表明，cellulose-g-（PNIPAAm&PCz）1 形成的胶束的分布范围比 cellulose-g-（PNIPAAm&PCz）2 窄。并且，cellulose-g-（PNIPAAm&PCz）2 形成的胶束在不同溶剂下的尺寸差异不大，但随着温度的升高而变大。由于接枝的 PNIPAAm 刷的热驱动链脱水，胶束表现出热增强荧光，这与单体的荧光随温度升高而降低相反。这些结果为基于纤维素的刺激响应胶束在药物输送和荧光探针领域的应用提供了潜力。
