Amphiphilic Diblock Terpolymer PMAgala-<i>b</i>-P(MAA-<i>co</i>-MAChol)s with Attached Galactose and Cholesterol Grafts and Their Intracellular pH-Responsive Doxorubicin Delivery
作者:Zhao Wang、Ting Luo、Ruilong Sheng、Hui Li、Jingjing Sun、Amin Cao
DOI:10.1021/acs.biomac.5b01227
日期:2016.1.11
In this work, a series of diblock terpolymer poly(6-O-methacryloyl-d-galactopyranose)-b-poly(methacrylic acid-co-6-cholesteryloxy hexyl methacrylate) amphiphiles bearing attached galactose and cholesterol grafts denoted as the PMAgala-b-P(MAA-co-MAChol)s were designed and prepared, and these terpolymer amphiphiles were further exploited as a platform for intracellular doxorubicin (DOX) delivery. First, employing a sequential RAFT strategy with preliminarily synthesized poly(6-O-methacryloyl-1,2:3,4-di-O-isopropylidene-d-galactopyranose) (PMAIpGP) macro-RAFT initiator and a successive trifluoroacetic acid (TFA)-mediated deprotection, a series of amphiphilic diblock terpolymer PMAgala-b-P(MAA-co-MAChol)s were prepared, and were further characterized by NMR, Fourier transform infrared spectrometer (FTIR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and a dynamic contact angle testing instrument (DCAT). In aqueous media, spontaneous micellization of the synthesized diblock terpolymer amphiphiles were continuously examined by critical micellization concentration assay, dynamic light scattering (DLS), and transmission electron microscopy (TEM), and the efficacies of DOX loading by these copolymer micelles were investigated along with the complexed nanoparticle stability. Furthermore, in vitro DOX release of the drug-loaded terpolymer micelles were studied at 37 °C in buffer under various pH conditions, and cell toxicities of as-synthesized diblock amphiphiles were examined by MTT assay. Finally, with H1299 cells, intracellular DOX delivery and localization by the block amphiphile vectors were investigated by invert fluorescence microscopy. As a result, it was revealed that the random copolymerization of MAA and MAChol comonomers in the second block limited the formation of cholesterol liquid-crystal phase and enhanced DOX loading efficiency and complex nanoparticle stability, that ionic interactions between the DOX and MAA comonomer could be exploited to trigger efficient DOX release under acidic condition, and that the diblock terpolymer micellular vector could alter the DOX trafficking in cells. Hence, these suggest the pH-sensitive PMAgala-b-P(MAA-co-MAChol)s might be further exploited as a smart nanoplatform toward efficient antitumor drug delivery.
在本研究中,设计并制备了一系列含有连接半乳糖和胆固醇接枝的二嵌段三元共聚物疏水亲水物,称为 PMAgala-b-P(MAA-co-MAChol)s,并进一步将其作为胞内阿霉素(DOX)递送的平台。首先,采用顺序 RAFT 策略,以预先合成的聚(6-O-甲基丙烯酰基-1,2:3,4-二-O-异丙叉基-d-吡喃半乳糖)(PMAIpGP)大分子 RAFT 引发剂和一系列连续的三氟乙酸(TFA)-介导的脱保护,制备了一系列非离子二嵌段三元共聚物 PMAgala-b-P(MAA-co-MAChol)s,并通过 NMR、傅里叶变换红外光谱仪(FTIR)、凝胶渗透色谱(GPC)、差示扫描量热法(DSC)和动态接触角测试仪(DCAT)进行了进一步表征。在水中,通过临界胶束浓度测定、动态光散射(DLS)和透射电镜(TEM)连续检测合成的二嵌段三元共聚物疏水亲水物的自发性微胶束化,并考察了这些共聚物胶束装载 DOX 的效能和复合纳米颗粒的稳定性。进一步研究了载药三元共聚物胶束在 37 °C 缓冲液中在不同 pH 条件下的体外 DOX 释放,并通过 MTT 试验检测了合成二嵌段疏水亲水物的细胞毒性。最后,通过倒置荧光显微镜对 H1299 细胞进行胞内 DOX 递送和定位研究。结果表明,第二嵌段中 MAA 和 MAChol 共聚单体的无规共聚限制了胆固醇液晶相的形成,提高了 DOX 装载效率和复合纳米颗粒的稳定性,DOX 与 MAA 共聚单体之间的离子相互作用可以利用,在酸性条件下可以触发高效的 DOX 释放,二嵌段三元共聚物胶束载体可以改变 DOX 在细胞中的转运。因此,这些结果表明,pH 敏感的 PMAgala-b-P(MAA-co-MAChol)s 可能进一步作为智能纳米平台用于高效抗癌药物递送。