Curcumin grafted poly(vinyl alcohol) for ascorbyyl palmitate encapsulation

In this work, encapsulation of ascorbyl palmitate (AP) into two polymeric nanoparticles, curcumin-grafted PV(OH) (Cur-PV(OH) and cinnamate-grafted PV(OH) (Cin-PV(OH), was carried out. The experiment covers polymer synthesis, particle fabrication, and encapsulation. Then, the stability of AP in the two polymeric nanoparticles and free AP in freeze-dried form and suspension form was investigated. The result showed that the encapsulated AP was more stable than the unencapsulated AP. AP in a freeze-dries form was more stable than AP in the suspension form. Moreover, AP kept under light-proof condition was more stable than that kept expected to light. AP inside the Cur-PV(OH) particles was more stable than AP co-encapsulated with curcumin inside the Cin-PV(OH) particles. Cur-PV(OH) nanospheres could be loaded with AP at the encapsulation efficiency of 80.85 ± 0.2%, at the loading of 29.00 ± 0.3% (wt of AP/total wt). An average diameter of AP-loaded Cur-PV(OH) particles was 269.80 ± 19.4 nm. The skin penetration study of AP-loaded Cur-PV(OH) particles on the ear skin of 6 month old pig using confocal laser fluorescence scanning microscope (CLFM) showed that hair follicle was the main skin penetrating routh of the AP-Cur-PV(OH) particles. Moreover, the accumulated Cur-PV(OH) at the hair follicles could release AP out into the surrounding tissue.

本研究将抗坏血酸棕榈酸酯（ascorbyl palmitate, AP）分别包封于两种聚合物纳米粒中，即姜黄素接枝聚乙烯醇（curcumin-grafted PV(OH), Cur-PV(OH)）与肉桂酸接枝聚乙烯醇（cinnamate-grafted PV(OH), Cin-PV(OH)）。实验内容涵盖聚合物合成、纳米粒制备与包封工艺。随后考察了两种聚合物纳米粒包封的AP，以及游离AP分别在冷冻干燥态与悬浮液态下的稳定性。结果表明，包封后的AP稳定性优于未包封的游离AP；冷冻干燥态AP的稳定性高于悬浮液态AP；避光储存条件下的AP稳定性优于光照条件下的AP。此外，Cur-PV(OH)纳米粒包封的AP稳定性优于与姜黄素共包封于Cin-PV(OH)纳米粒中的AP。Cur-PV(OH)纳米球对AP的包封率可达80.85 ± 0.2%，载药量为29.00 ± 0.3%（AP质量占总质量的百分比）。载AP Cur-PV(OH)纳米粒的平均粒径为269.80 ± 19.4 nm。采用共聚焦激光扫描荧光显微镜（confocal laser fluorescence scanning microscope, CLFM），以6月龄猪耳皮肤为模型，开展载AP Cur-PV(OH)纳米粒的皮肤渗透研究，结果显示毛囊是AP-Cur-PV(OH)纳米粒的主要皮肤渗透途径；且富集于毛囊处的Cur-PV(OH)可将AP释放至周围组织中。