海藻酸辛酯衍生物的制备及其载药微纳米胶囊的释药性

以1-溴辛烷为疏水改性剂，采用双分子亲核取代反应(SN2)制备海藻酸辛酯衍生物(OAD)，通过红外光谱(FT-IR)、核磁谱图(1H NMR)对其结构进行鉴定，并采用热重分析(TGA)、X射线衍射(XRD)、荧光光谱(FM)、表面张力(SFT)、透射电镜(TEM)、激光粒度和zeta电位分析仪对其性能进行了表征。 结果表明，辛基侧链的接枝使OAD的分子内氢键断裂，其热稳定性下降，失重率增大，同时伴随其微晶结构的改变。荧光测试中，随聚合物浓度的增大，芘在其溶液中的第一电子振动峰与第三电子振动峰的荧光强度之比(I1/I3)呈现逐步下降的趋势。并且辛基侧链的接枝使海藻酸钠(SA)的临界聚集浓度(CAC)由1.09 g/L降为0.34 g/L，而其SFT也随其浓度的增大而逐步降低，两者同时体现其具有良好的两亲性。 另外，OAD能自聚集形成类胶束的球形结构，相比SA，OAD胶束的水动力学粒径(dH)变小，由255 nm变为193.2 nm，zeta电位也降低，由-36.4 mV降为-39.3 mV，说明OAD具有一定的胶体界面活性. 采用 OAD 胶束负载布洛芬制备载药微纳米胶囊，其对药物的释放具有一定的缓释作用，药物的释放过程属于 Non-Fickian 扩散机制。

Synthesis of Octyl Alginate Derivative and its Drug-loaded Micro-/Nano-capsules for the Drug Delivery

Octyl Alginate Derivative (OAD), prepared by bimolecular nucleophilic substitution reaction (SN2) with 1-Bromooctane as a hydrophobic modifier, was characterized by means of Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (1H NMR) to confirm its structure. Meanwhile, the performance of OAD was characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), fluorescence spectrum (FM), surface tension (SFT), transmission electron microscope (TEM), laser particle size and zeta potential analyzers. The results of FTIR and 1H NMR showed that, the octyl group was suc-cessfully grafted onto the alginate backbone. It can be seen from the TGA and XRD that, due to the grafting octyl side chains, the intramolecular hydrogen bond of OAD was broken, thus resulting in the de-crease of its thermal stability, the increase of its weight loss rate in TGA study and the change of its micro-crystalline structure. From the fluorescence measurement, with the increase of OAD concentration, the ra-tio of the first electron vibration peak to the third electron vibration peak fluorescence intensity (I1/I3) that was related to the micro-environmental polarity surrounding pyrene molecules gradually decreased, indi-cating the reduction of the micro-environmental polarity. It can be deduced from I1/I3 value that, as a re-sult of the grafting of octyl side chains, the critical aggregation concentration (CAC) of sodium alginate (SA) decreased from 1.09 g/L to 0.34 g/L. Meanwhile, the SFT gradually decreased as the concentration increased. Both of the FM and SFT results revealed that OAD had good amphipathicity, though they ob-tained the different CAC. From the TEM, it intuitively displayed that OAD formed micelle-like self-aggregates, which appeared spherical structure. Furthermore, compared with SA, the hydrodynamic particle size (dH) of OAD decreased from 255 nm to 193.2 nm. Besides, its zeta potential also decreases from -36.4 mV to -39.3 mV. These results showed that OAD possessed certain colloidal interface activity. The drug-loaded micro-/nano-capsules were prepared by the use of OAD micelles to load ibuprofen, which have certain sustained-release property, Moreover, the release profile was fitted well with the Non-Fickian diffusion model.