Controlled Micelle Formation and Stable Capture of Hydrophobic Drug by Alkylated POSS Methacrylate Block Copolymers AITranslate

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DOI：https://doi.org/10.1021/acsapm.9b00412

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Design of polymeric micelles, formed by self-assembly of amphiphilic block copolymers, is crucial for encapsulation of poorly soluble drugs, leading to the development of promising carrier systems. Herein, we synthesized amphiphilic diblock copolymers of 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) and methacrylate R-polyhedral oligomeric silsesquioxanes (POSS) (vertex R-groups of POSS cage modified with ethyl (C2H5), hexayl (C6H13), octayl (C8H17) alkyl chain) via RAFT polymerization technique. Polymeric micelle was formed in aqueous environment, and the absolute size was calculated to be around 26–43 nm. The increased alkyl chain length of the R-groups of POSS led to loosely packed association of the micelles. The polymeric micelles encapsulated the hydrophobic model drugs (paclitaxel and α-tocopherol), and the encapsulation efficiency was strongly dependent on the structure of drug molecules. The drug-loaded micelles were stable for 5 days at 25 °C. The release % of both the drugs from the micelles was at a negligible level or below 20%, suggesting the strong interaction between the R-POSS moieties and the drug molecules. Cellular uptake of the micelles by HeLa cells was quantitatively analyzed using a FITC-labeled paclitaxel (FITC-PTX). All the micelles were internalized by the cell after 2 h, and cellular uptake of PTX-loaded micelle composed of the C6H13–POSS copolymer reached the highest level, suggesting that the alkyl chain length is one of the tunable factors for the cellular uptake. These diblock copolymers have great potential as a hydrophobic drug carrier molecule and its delivery to specific sites.