关键词: 一锅法, 组氨酸, pH敏胶束

One-pot reaction strategy has been widely used in the synthesis of different polymer architectures which accelerates synthetic procedure and reduces the number of reactions as well as purification steps, therefore leading to more environmentfriendly products. Imidazole group of histidine (His) can exhibit proton sponge effect at different pH values. We design a polymer micelles with histidine to achieve the pH response capability. Synthesis of (PEG-b-poly-hydroxyethyl methacrylate) PEG-b-PHEMA block copolymer combined click chemistry and atom transfer radical polymerization by one-pot syntheses strategy, then through esterification reaction graft histidine on the polymer side chain to get (polyethylene glycol- b-poly-hydroxyethyl methacrylate-g-histidine) PEG-b-PHEMA(His). The reactions are controllable, and the structure of obtained copolymer is well characterized. PEG-b-PHEMA, PEG-b-PHEMA(His)'s structures were characterized by ¹H NMR and GPC tests. The resulting data shown by GPC to give the exact molecular weight and narrow distribution. M_n=8.2×10³～13.0×10³ g/mol, PDI=1.27～1.51. After the preparation of pH-sensitive drug copolymer micelles in borate buffer solution, the dynamic light scattering (DLS) test was done to test the particle size of the micelles. Then we used fluorescence spectroscopy to test its critical micelle concentration. The micelle diameter increases and the critical micelle concentration gradually reduces as the histidine graft ratio increase. Transmission electron microscopy (TEM) tests showed that the polymer micelle is spherical and narrow particle size distribution and the conclusion is consistent with the DLS test. Also, the acid-base titration and medicine released experiments curves proved that the product micelles have the ability of pH-sensitive response. The embedding of anticancer drug doxorubicin (DOX) was achieved by phase transfer method to get PEG-b-PHEMA(His)@DOX. The drug release rate was measured by counting the optical density (OD) value. The result shows that the release rate of DOX increased from 10% to 40%, thus demonstrating that the PEG-b-PHEMA(His) DOX system has a pH-sensitive response capability. Such micelles can be used as drug carriers for biomedical applications.

Key words: one-pot reaction, histidine, pH-sensitive micelle