Biying, A. O., Mothe, S. R., Jackson, A. W., Kanaujia, P., & Thoniyot, P. (2024). Effects of polymer microstructure introduced by radical ring-opening polymerization on nanoencapsulation and controlled release. Polymer, 307, 127284. https://doi.org/10.1016/j.polymer.2024.127284
Abstract:
In this study, the effect of the polymer structural difference introduced by radical ring-opening polymerization (rROP) of a cyclic ketene acetal (CKA) monomer, analogous to ε-caprolactone (CL), on the nanoencapsulation and controlled release of hydrophobic actives curcumin and fenofibrate was explored. The two chosen polymers are amphiphilic diblock copolymers namely methoxy poly(ethylene glycol)-b-poly(ε-caprolactone) (mPEG-b-PCL) and methoxy poly(ethylene glycol)-b-poly(2-methylene-1,3-dioxepane) (mPEG-b-PMDO). Both polymers serve as a good comparison as they have a similar average molecular weight (Mn) and the same hydrophilic PEG chains with the main difference in microstructure of hydrophobic PCL and PMDO chains. Nuclear magnetic resonance spectroscopy (NMR) (1H and 13C), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction (X-RD) confirmed the structures of the polymers. mPEG-b-PMDO possesses less crystallinity or is more amorphous as compared to the linear mPEG-b-PCL due to branching or polymer disorder in the hydrophobic segment as a result of radical mechanism operating in rROP. The subsequent nanoencapsulation of hydrophobic active curcumin with mPEG-b-PMDO yielded higher loading content (LC) and encapsulation efficiency (EE) in the hydrophobic core of the nanoparticle (NP) due to more hydrophobic interactions between hydrophobic core and hydrophobic active. In contrast, lower LC and EE were observed for the nanoencapsulation of fenofibrate with mPEG-b-PMDO. The further release experiments were carried out in the aqueous and hydro-alcoholic systems over a period of 24 h at 37 °C. These experiments further supported our hypothesis regarding the influence of polymer structure, revealing slower, controlled, and more consistent release profiles for both curcumin and fenofibrate with mPEG-b-PMDO compared to mPEG-b-PCL. Our approach could open new opportunities for utilizing this polymer in personal care and biomedical applications.
License type:
Attribution 4.0 International (CC BY 4.0)
Funding Info:
This research / project is supported by the A*STAR - AME IAF-PP
Grant Reference no. : A1786a0025