pH和氧化双响应性聚β硫酯化合物的制备及其聚集性质的研究

Synthesis and Self-assembly of pH and ROS Dual Responsive Poly(β-thioester)s

以二丙烯酸二乙二醇酯(DEDA),二硫苏糖醇(DTT),丙烯酰氯(AC),巯基聚乙二醇(PEG-SH,Mn=2000 Da)为原料,通过迈克尔加成反应合成了p H和活性氧(ROS)双响应型的两亲性聚β硫酯化合物(D-D-P),利用核磁共振(NMR)对聚合物结构进行了表征,利用凝胶渗透色谱(GPC)表征了聚合物D-D-P分子量(Mn=50400).利用透析法使D-D-P自组装成纳米粒子,用纳米粒度分析仪(DLS)表征了粒径约280 nm,用透射电子显微镜(TEM)表征了其形貌.通过粒径变化测试和尼罗红(NR)荧光测试对纳米粒子在酸性(p H≈5)和氧化条件下(H2O2)的解散行为进行了研究,验证了D-D-P的p H和ROS双响应性能.通过紫外吸收测试对包裹抗癌药物阿霉素(DOX)的纳米粒子在酸性和氧化条件下的释放进行了研究,并且在MCF-7细胞中对DOX的释放进行了进一步的验证.

The Michael addition reaction, which is a mild reaction between activated olefins and nucleophiles, has been widely used in synthesis of tailored macromolecular architectures. We designed a copolymer nanoparticle to obtain the ROS and p H dual responsive capability. We synthesized the amphiphilic poly（β-thioester）s copolymers（D-D-P） composed of di（ethylene glycol） diacrylate（DEDA）, DL-dithiothreitol（DTT）, acryloyl chloride（AC） and hydrophilic PEG-SH with average Mn=2000 g·mol-1 via Michael addition reaction. The reactions are facile and controllable, and the structures of acquired copolymers are well characterized. The structures of the polymers were confirmed by 1H NMR, and the number molecular weight and distribution of the copolymer D-D-P was measured by GPC（Mn=50400）. D-D-P could self-assemble into nanoparticles with core-shell structures by dialysis method due to the composition of hydrophilic side chains and hydrophobic polymer backbones. After the preparation of ROS and p H dual responsive D-D-P nanoparticles in phosphate buffer solution, the morphology and size of D-D-P nanoparticles were observed by transmission electron microscopy（TEM） and dynamic light scattering（DLS） showed that the number size distribution of nanoparticles was around 280 nm. Nile Red（NR） is a unique neutral hydrophobic molecule, which shows very weak fluorescence in aqueous solution and can emit strong fluorescence in the hydrophobic environment. NR absorption and emission spectra are strongly dependent on environment polarity, which make it as a probe molecule that is widely used in the evaluation of microenvironment polarity. The disassembly behaviors of D-D-P nanoparticles were investigated by the change of the nanoparticle size and NR fluorescence spectra. The diameter of nanoparticle decreased under p H 5 and ROS environment conditions, and the NR fluorescence also became weak under p H 5 and ROS environment conditions, which could be attributed to the gradual dissociation of nanoparticles, proving the ROS and p H dual responsive properties of the poly（β-thioester）s. The release behaviors of the DOX encapsulated D-D-P nanoparticles in acidic and oxidative condition were studied by the UV absorption and were further proved in MCF-7 cells.