To control the release of nerve growth factor (NGF) in the injured peripheral nerve, NGF-loaded chitosan/PLGA composite microspheres ionically cross-linked by tripolyphosphate (TPP/Chitosan/PLGA-NGF) were prepared. The encapsulation efficiency of NGF ranged from 83.4 ± 1.5 % to 72.1 ± 1.6 % with TPP concentrations from 1 % to 10 %. Zeta potential and FT-IR analyses together with confocal microscopy demonstrated that multiple NGF-loaded PLGA microspheres were embedded in chitosan matrix, the mean size of TPP/Chitosan/PLGA-NGF microspheres ranged from 40.2 ± 3.4 to 49.3 ± 3.1 μm. The increase of TPP concentration improved the network stability and decreased the swelling ratio, resulting in the decreased NGF release from 67.7 ± 1.2 % to 45.7 ± 0.8 % in 49 days. The sustained release of NGF could promote PC12 cells differentiation and neurite growth in vitro. Moreover, in comparison with NGF solution without microencapsulation, TPP/Chitosan/PLGA-NGF microspheres enhanced sciatic nerve regeneration and prevented gastrocnemius muscle atrophy in rats. These results demonstrate the feasibility of using TPP/Chitosan/PLGA-NGF microspheres for neural tissue repair.

为了控制受伤的周围神经中神经生长因子（NGF）的释放，制备了由三聚磷酸酯（TPP /壳聚糖/ PLGA-NGF）离子交联的NGF负载壳聚糖/ PLGA复合微球。NGF的封装效率为83.4±1.5％至72.1±1.6％，TPP浓度为1％至10％。Zeta电位和FT-IR分析以及共聚焦显微镜表明，壳聚糖基质中嵌入了多个NGF负载的PLGA微球，TPP /壳聚糖/ PLGA-NGF微球的平均大小为40.2±3.4至49.3±3.1μm。TPP浓度的增加改善了网络稳定性并降低了溶胀率，导致NGF释放在49天内从67.7±1.2％降至45.7±0.8％。NGF的持续释放可以促进PC12细胞分化和神经突生长体外。此外，与没有微囊化的NGF溶液相比，TPP /壳聚糖/ PLGA-NGF微球增强了大鼠坐骨神经的再生并防止了腓肠肌萎缩。这些结果证明了使用TPP /壳聚糖/ PLGA-NGF微球进行神经组织修复的可行性。