BACKGROUND During the past few decades, drug delivery system (DDS) has attracted many interests because it could enhance the therapeutic effects of drugs and reduce their side effects. The advent of nanotechnology has promoted the development of nanosized DDSs, which could promote drug cellular uptake as well as prolong the half-life in blood circulation. Novel polymer micelles formed by self-assembly of amphiphilic polymers in aqueous solution have emerged as meaningful nanosystems for controlled drug release due to the reversible destabilization of hydrophobic domains under different conditions. RESULTS The amphiphilic polymers presented here were composed of cholesterol groups end capped and poly (poly (ethylene glycol) methyl ether methacrylate) (poly (OEGMA)) as tailed segments by the synthesis of cholesterol-based initiator, followed by atom transfer radical polymerization (ATRP) with OEGMA monomer. FT-IR and NMR confirmed the successfully synthesis of products including initiator and polymers as well as the Mw of the polymers were from 33,233 to 89,088 g/mol and their corresponding PDI were from 1.25 to 1.55 by GPC. The average diameter of assembled polymer micelles was in hundreds nanometers demonstrated by DLS, AFM and SEM. The behavior of the amphiphilic polymers as micelles was investigated using pyrene probing to explore their critical micelle concentration (CMC) ranging from 2.53 × 10-4 to 4.33 × 10-4 mg/ml, decided by the balance between cholesterol and poly (OEGMA). Besides, the CMC of amphiphilic polymers, the quercetin (QC) feeding ratio and polarity of solvents determined the QC loading ratio maximized reaching 29.2% certified by UV spectrum, together with the corresponding size and stability changes by DLS and Zeta potential, and thermodynamic changes by TGA and DSC. More significantly, cholesterol end-capped polymer micelles were used as nanosized systems for controlled drug release, not only alleviated the cytotoxicity of QC from 8.6 to 49.9% live cells and also achieved the QC release in control under different conditions, such as the presence of cyclodextrin (CD) and change of pH in aqueous solution. CONCLUSIONS The results observed in this study offered a strong foundation for the design of favorable polymer micelles as nanosized systems for controlled drug release, and the molecular weight adjustable amphiphilic polymer micelles held potential for use as controlled drug release system in practical application.

中文翻译：

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用于控制药物输送的胆固醇封端聚合物胶束的自组装。


背景技术在过去的几十年中，药物递送系统(DDS)因其能够增强药物的治疗效果并减少其副作用而引起了许多人的兴趣。纳米技术的出现促进了纳米DDS的发展，它可以促进药物细胞摄取并延长血液循环中的半衰期。由于疏水域在不同条件下的可逆不稳定，由两亲性聚合物在水溶液中自组装形成的新型聚合物胶束已成为有意义的药物控制释放纳米系统。结果本文提出的两亲性聚合物由胆固醇基团封端和聚（聚（乙二醇）甲醚甲基丙烯酸酯）（聚（OEGMA））作为尾部片段，通过合成胆固醇基引发剂，然后进行原子转移自由基聚合而组成。 ATRP) 与 OEGMA 单体。 FT-IR和NMR证实成功合成了包括引发剂和聚合物在内的产物，并且通过GPC测定聚合物的Mw为33,233至89,088 g/mol，相应的PDI为1.25至1.55。 DLS、AFM 和 SEM 证明组装的聚合物胶束的平均直径为数百纳米。使用芘探测来研究两亲性聚合物作为胶束的行为，以探索其临界胶束浓度 (CMC)，范围为 2.53 × 10-4 至 4.33 × 10-4 mg/ml，由胆固醇和聚 (OEGMA) 之间的平衡决定。此外，两亲聚合物的CMC、槲皮素(QC)进料比和溶剂的极性决定了QC负载比最大达到29。2% 通过 UV 光谱认证，以及 DLS 和 Zeta 电位的相应尺寸和稳定性变化，以及 TGA 和 DSC 的热力学变化。更重要的是，胆固醇封端的聚合物胶束用作纳米级药物控制释放系统，不仅将QC的细胞毒性从8.6％活细胞减轻至49.9％，而且还实现了不同条件下QC的控制释放，例如存在环糊精 (CD) 和水溶液 pH 值的变化。结论本研究观察到的结果为设计有利的聚合物胶束作为纳米级药物控释系统提供了坚实的基础，并且分子量可调的两亲性聚合物胶束在实际应用中具有作为控释药物系统的潜力。