Preparation of curcumin-loaded microparticles from star-shaped poly(lactic acid) stereo-complex

The development of new biocompatible and biodegradable microparticles offering longer sustained drug release and greater stability than existing systems remains critical for subcutaneous injections. In this study, new microparticles based on a polylactide (PLA) stereo-complex (scPLA) stabilized with stearyl poly(ethylene glycol) (stPEG) were prepared. Curcumin, as a carrier drug, was encapsulated inside the prepared scPLA microparticles using the solution mixing method. Optical PLA isomers were prepared to enhance the loading capacity using mannose as a polyfunctional initiator, and scPLA samples were prepared via solution precipitation using the corresponding isomers. Varying the molecular weights and combinations of the isomers yielded scPLA microparticles with sizes ranging from 1.0 to 2.2 μm. These particles exhibited a single melting point ( T m ) at approximately 215°C, confirming the absence of PLA crystals ( T m = 150°C). The desired curcumin-containing scPLA microparticles were successfully prepared by co-introducing curcumin and stPEG in the solution, with the maximum curcumin loading capacity reaching 14 wt%. scPLA microparticles loaded with curcumin showed significantly superior sustained release properties compared to nanoparticles composed of well-known mPEG-PLA copolymers also loaded with curcumin. This indicates that the highly stable crystalline structure of scPLA enabled the long-term drug release. • A star-shaped PLA stereo-complex microparticles with numerous voids were prepared. • Curcumin was loaded into microparticles with the help of stearyl-PEG (14.3 wt% and 98.3% loading efficiency). • Longer sustainable drug delivery capsule was successfully developed.