Xiao Min-Cong, Chou Ya-Hsuan, Hung Yu-Ning, Hu Shang-Hsiu, Chiang Wen-Hsuan
Department of Chemical Engineering, National Chung Hsing University, Taichung 402, Taiwan.
Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 300, Taiwan.
Mater Sci Eng C Mater Biol Appl. 2020 Nov;116:111277. doi: 10.1016/j.msec.2020.111277. Epub 2020 Jul 7.
Zoledronic acid (ZA), a third-generation nitrogen-heterocycle-containing bisphosphonate, has been frequently used as an anti-resorptive agent to treat cancer-involved hypercalcemia and painful bone metastases. In order to expand the clinical applications of ZA toward the extraskeletal tumor treatment, it is essential to develop the functionalized nanocarriers capable of carrying high ZA payload and achieving intracellular triggered ZA release. In this end, the ZA-encapsulated hybrid polymeric nanoparticles were fabricated in this work by co-association of the amphiphilic diblock copolymer poly(lactic-co-glycolic acid)-b-poly(ethylene glycol) (PLGA-b-PEG), tocopheryl polyethylene glycol succinate (TPGS) segments and ionic complexes composed of ZA molecules and branched poly(ethylenimine) (PEI) segments. Notably, the ionic pairings of PEI segments with ZA molecules not only assisted encapsulation of ZA into the PLGA-rich core of hybrid nanoparticles but also reduced adhesion of ZA on the surfaces of hydrophobic cores, thus largely increasing ZA loading capacity. The dynamic light scattering (DLS) and transmission electron microscopy (TEM) characterization revealed that the ZA/PEI-loaded nanoparticles had a well-dispersed spherical shape. Moreover, compared to short PEI (1.8 kDa) segments, the longer PEI (10 kDa) segments formed more robust complexes with ZA molecules, thus prominently promoting ZA loading content of hybrid nanoparticles and their colloidal stability. Interestingly, with the suspension pH being reduced from 7.4 to 5.0, the considerable disruption of ZA/PEI ionic complexes owing to the acid-activated protonation of ZA molecules and the developed proton sponge-like effect inside the nanoparticle matrix upon the protonated PEI segments facilitated the rapid release of ZA molecules from drug-loaded hybrid nanoparticles. The results of in vitro cellular uptake and cytotoxicity studies showed that the ZA/PEI-loaded hybrid nanoparticles were internalized by MCF-7 cells upon energy-dependent endocytosis and displayed a superior cytotoxic effect to free ZA. This work demonstrates that the unique ZA/PEI-loaded hybrid polymeric nanoparticles display great promise for anticancer applications.
唑来膦酸（ZA）是第三代含氮杂环双膦酸盐，常被用作抗吸收剂来治疗癌症相关的高钙血症和疼痛性骨转移。为了扩大ZA在骨骼外肿瘤治疗方面的临床应用，开发能够携带高剂量ZA并实现细胞内触发ZA释放的功能化纳米载体至关重要。为此，在本研究中，通过两亲性二嵌段共聚物聚（乳酸 - 乙醇酸）-b-聚（乙二醇）（PLGA-b-PEG）、生育酚聚乙二醇琥珀酸酯（TPGS）片段与由ZA分子和支化聚（乙烯亚胺）（PEI）片段组成的离子复合物的共缔合，制备了包封ZA的杂化聚合物纳米颗粒。值得注意的是，PEI片段与ZA分子的离子配对不仅有助于将ZA包封到杂化纳米颗粒富含PLGA的核心中，还减少了ZA在疏水核心表面的粘附，从而大大提高了ZA的负载能力。动态光散射（DLS）和透射电子显微镜（TEM）表征表明，负载ZA/PEI的纳米颗粒具有分散良好的球形形状。此外，与短PEI（1.8 kDa）片段相比，较长的PEI（10 kDa）片段与ZA分子形成了更强健的复合物，从而显著提高了杂化纳米颗粒的ZA负载量及其胶体稳定性。有趣的是，随着悬浮液pH从7.4降至5.0，由于ZA分子的酸活化质子化以及质子化PEI片段在纳米颗粒基质内产生的类似质子海绵的效应，ZA/PEI离子复合物发生了相当大的破坏，这促进了ZA分子从载药杂化纳米颗粒中的快速释放。体外细胞摄取和细胞毒性研究结果表明，负载ZA/PEI的杂化纳米颗粒通过能量依赖性内吞作用被MCF-7细胞内化，并对游离ZA表现出优异的细胞毒性作用。这项工作表明，独特的负载ZA/PEI的杂化聚合物纳米颗粒在抗癌应用中显示出巨大的潜力。
