Ning W et al. (2018), Novel Amphiphilic, Biodegradable, Biocompatible...

ECB-ART-47123

Polymers (Basel) 2018 Feb 22;102:. doi: 10.3390/polym10020214.

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Novel Amphiphilic, Biodegradable, Biocompatible, Thermo-Responsive ABA Triblock Copolymers Based on PCL and PEG Analogues via a Combination of ROP and RAFT: Synthesis, Characterization, and Sustained Drug Release from Self-Assembled Micelles.

Ning W , Shang P , Wu J , Shi X , Liu S .

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Well-defined novel, linear, biodegradable, amphiphilic thermo-responsive ABA-type triblock copolymers, poly[2-(2-methoxyethoxy) ethyl methacrylate-co-oligo(ethylene glycol) methacrylate]-b-poly(ε-caprolactone)-b-poly[2-(2-methoxyethoxy) ethyl methacrylate-co-oligo(ethylene glycol) methacrylate] [P(MEO₂MA-co-OEGMA)-b-PCL-b-P(MEO₂MA-co-OEGMA)] (tBPs), were synthesized via a combination of ring-opening polymerization (ROP) of ε-caprolactone (εCL) and reversible addition-fragmentation chain transfer polymerization (RAFT) of MEO₂MA and OEGMA comonomers. The chemical structures and compositions of these copolymers were characterized using Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (¹H NMR). The molecular weights of the copolymers were obtained using gel permeation chromatography (GPC) measurements. Thermo-responsive micelles were obtained by self-assembly of copolymers in aqueous medium. The temperature sensitivity and micelllization behavior of amphiphilic triblock copolymers solutions were studied by transmittance, fluorescence probe, surface tension, dynamic light scattering (DLS) and transmission electron microscopy (TEM). A hydrophobic drug, anethole, was encapsulated in micelles by using the dialysis method. The average particle sizes of drug-loaded micelles were determined by dynamic light scattering measurement. In vitro, the sustained release of the anethole was performed in pH 7.4 phosphate-buffered saline (PBS) at different temperatures. Results showed that the triblock copolymer''s micelles were quite effective in the encapsulation and controlled release of anethole. The vial inversion test demonstrated that the triblock copolymers could trigger the sol-gel transition which also depended on the temperature, and its sol-gel transition temperature gradually decreased with increasing concentration. The hydrogel system could also be used as a carrier of hydrophobic drugs in medicine.

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References [+] :

Chen, Biodegradable amphiphilic copolymers based on poly(epsilon-caprolactone)-graft chondroitin sulfate as drug carriers. 2008, Pubmed

	Scheme 1. Synthesis of triblock copolymer P(MEO2MA-co-OEGMA)-b-PCL-b-P(MEO2MA-co-OEGMA).
	Figure 1. Photographs of the triblock copolymers aqueous solutions (2 mg·mL−1) at 25 °C (a), 35 °C (b), and 45 °C (c).
	Figure 2. Curves of the triblock copolymers aqueous solutions transmittance versus temperatures with (a) different degrees of polymerization, (b) the different content of OEGMA, (c) different concentrations of tBP3 aqueous solutions, and (d) LCST versus the tBP3 concentration.
	Figure 3. The CMC of the triblock copolymer tBP2 and tBP3 as determined by the emission spectra (a) or automatic surface tension meter (b).
	Figure 4. Size distributions of tBPs aqueous solutions (2 mg·mL−1) (a) and the evolution of the diameters of the nanoparticles of the tBP3 versus temperature (2 mg·mL−1) (b).
	Scheme 2. Schematic representation of the self-assembled thermo-sensitive core–shell micelles for temperature-stimulated drug release and gelation of tPBs.
	Figure 5. TEM images and size distribution profiles of tBP3 micelles in distilled water, determined by DLS measurement at 25 °C (a) and 35 °C (b) (2 mg·mL−1).
	Figure 6. Photographs of P(MEO2MA-co-OEGMA)-b-PCL-b-P(MEO2MA-co-OEGMA) aqueous solutions at different temperature: (left) tBP1, tBP2, and tBP3 aqueous solutions (25 wt %) at different temperatures; and (right) various concentrations of tBP3 aqueous solutions at different temperatures.
	Figure 7. Photographs of anethole solution: (A) 0.1% anethole in PBS; (B) A1-tBP3 (DL = 5.1%); and (C) A2-tBP3 (DL = 7.9%).
	Figure 8. Intensity size distribution: (A) tBP3 (DL = 0); (B) A1-tBP3 (DL = 5.1%) and (C) A2-tBP3 (DL = 7.9%).
	Figure 9. The drug release profiles (A) of anethole-loaded micelles: (a) pure anethole; (b) A1-tBP3 (DL = 5.1%) at 37 °C; (c) A1-tBP3 (DL = 5.1%) at 25 °C; (d) A2-tBP3 (DL = 7.9%) at 37 °C; (e) A2-tBP3 (DL = 7.9%) at 25 °C; and (B) of anethole-loaded micelles of A-tBP1 (DL = 5.7%), A-tBP2 (DL = 5.3%), and A-tBP3 (DL = 5.1%) at 37 °C.