Synthesis, characterization, and evaluation of paclitaxel loaded in six-arm star-shaped poly(lactic-co-glycolic acid)

Yongxia Chen,1,3,* Ziying Yang,1,* Chao Liu,1 Cuiwei Wang,1 Shunxin Zhao,2 Jing Yang,1 Hongfan Sun,1 Zhengpu Zhang,2 Deling Kong,1 Cunxian Song1 1Tianjin Key Laboratory of Biomaterial Research, Institute of Biomedical Engineering, Chinese Academy of Medical Science and Peking Union Medical College, 2Institute of Polymer Chemistry, Nankai University, 3Center for Medical Device Evaluation of Tianjin, Tianjin, People's Republic of China  *These authors contributed equally to this work Background: Star-shaped polymers provide more terminal groups, and are promising for application in drug-delivery systems. Methods: A new series of six-arm star-shaped poly(lactic-co-glycolic acid) (6-s-PLGA) was synthesized by ring-opening polymerization. The structure and properties of the 6-s-PLGA were characterized by carbon-13 nuclear magnetic resonance spectroscopy, infrared spectroscopy, gel permeation chromatography, and differential scanning calorimetry. Then, paclitaxel-loaded six-arm star-shaped poly(lactic-co-glycolic acid) nanoparticles (6-s-PLGA-PTX-NPs) were prepared under the conditions optimized by the orthogonal testing. High-performance liquid chromatography was used to analyze the nanoparticles' encapsulation efficiency and drug-loading capacity, dynamic light scattering was used to determine their size and size distribution, and transmission electron microscopy was used to evaluate their morphology. The release performance of the 6-s-PLGA-PTX-NPs in vitro and the cytostatic effect of 6-s-PLGA-PTX-NPs were investigated in comparison with paclitaxel-loaded linear poly(lactic-co-glycolic acid) nanoparticles (L-PLGA-PTX-NPs). Results: The results of carbon-13 nuclear magnetic resonance spectroscopy and infrared spectroscopy suggest that the polymerization was successfully initiated by inositol and confirm the structure of 6-s-PLGA. The molecular weights of a series of 6-s-PLGAs had a ratio corresponding to the molar ratio of raw materials to initiator. Differential scanning calorimetry revealed that the 6-s-PLGA had a low glass transition temperature of 40°C–50°C. The 6-s-PLGA-PTX-NPs were monodispersed with an average diameter of 240.4±6.9 nm in water, which was further confirmed by transmission electron microscopy. The encapsulation efficiency of the 6-s-PLGA-PTX-NPs was higher than that of the L-PLGA-PTX-NPs. In terms of the in vitro release of nanoparticles, paclitaxel (PTX) was released more slowly and more steadily from 6-s-PLGA than from linear poly(lactic-co-glycolic acid). In the cytostatic study, the 6-s-PLGA-PTX-NPs and L-PLGA-PTX-NPs were found to have a similar antiproliferative effect, which indicates durable efficacy due to the slower release of the PTX when loaded in 6-s-PLGA. Conclusion: The results suggest that 6-s-PLGA may be promising for application in PTX delivery to enhance sustained antiproliferative therapy. Keywords: PTX, polymer, drug delivery, nanoparticles, PLGA, antiproliferative therap