pH-Sensitive poly(methacrylic acid)-block-hydroxyl-terminated polybutadiene-block-poly(methacrylic acid) (PMAA-b-HTPB-b-PMAA) was synthesized and then hydrogenated in this work. The chain structure, phase behavior and thermal properties were characterized by 1H NMR, FTIR, XRD, DSC, TGA, etc., and the physicochemical and biomedical properties were investigated via fluorescence spectroscopy, TEM, DLS, loading and release of drug and MTT, and so on. The experimental results indicated that the hydrogenation led to the change in the chain aggregate structure of hydrophobic HTPB blocks and the formation of more stable spherical core-shell micelle aggregates, and the critical micelle concentration decreased from 41.8 mg L−1 before hydrogenation to 4.4 mg L−1 after hydrogenation. The hydrogenated block copolymer micelle aggregates exhibited pH-triggered response, and could entrap twice as much hydrophobic drug as the unhydrided counterparts and the encapsulation efficiency was significantly improved, which makes them fine to meet the requirements for drug carriers. Therefore, the hydrogenated PMAA-b-HTPB-b-PMAA copolymer micelles as drug target release carriers can be well used in the field of prevention and treatment of cancers.
Luo Yan-Ling,Yang Xiao-Li,Xu Feng,Chen Ya-Shao,Zhao Xu
pH-sensitive poly(methacrylic acid)- block -hydroxyl-terminated polybutadiene- block -poly(methacrylic acid) block copolymers were synthesized by atom transfer radical polymerization of t -butyl methacrylate and follow-up acidolysis. The copolymers can spontaneously assemble into stable and nearly spherical micelle aggregates in aqueous solution, with hydrodynamic diameters ( D
h
) from 51 to 92 nm and critical micelle concentration of 3.90–7.76 mg L −1 . Z eta potentials were found to be increased with increasing (monomer)/(initiator) molar ratios. A pH-dependent phase behavior is produced at approximately 5.4–5.6, as determined by D
h
and I
335 / I
332 fluorescence intensity ratios. The in vitro camptothecin (CPT) release was compositional and pH dependent, and the cumulative CPT release below pH 7.2 was higher than that in pH 7.4. They could inhibit the premature burst CPT release. The copolymer micelles were low in cytotoxicity even at a micellar concentration of 800 mg L −1 , and therefore they may be used as potential drug-delivery carriers.
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