Enhanced, polylactide

In the preparation of microspheres by solvent evaporation from oil-in-water emulsions, the presence of base (NaOH) was found to enhance the release of thioridazine from polylactide micro-spheres. The amount of drug release as a function of time was dependent on the amount of base added to the aqueous phase of the emulsion. Scanning electron micrographs indicate that this increased drug release may be due to modification of the internal structure of the microspheres by sodium hydroxide during fabrication. 

FONG ET AL. Enhancing Drug Release from Polylactide Microspheres... 

These polylactides are known to degrade by hydrolysis (4.) Therefore, the most obvious explanation is that the molecular weight of the polymer is decreased by the NaOH. It has been reported (6) that drug release is increased when the polymer molecular weight is lowered. This would then account for the enhanced drug release observed. 

Kim, I. H., and Jeong, Y G. (2010], Polylactide/exfoliated graphite nanocomposites with enhanced thermal stability, mechanical modulus, and electrical conductivity. J. Polym. Sci. Polym. Phys., 8, pp. 850-858. 

Weiler, W. and Gogolewski, S. (1996) Enhancement of the mechanical properties of polylactides by solid-state extrusion. I. Poly(D-lactide). Biomaterials, 17 (5), 529-535. 

Montmorillonite (MMT), a smectite clay, is probably the most extensively studied nanomaterial in terms of mechanical, thermal, fire retardant or crystallization behavior of polylactide, especially when these nanoparticles are organically modified allowing the achievement of intercalated and exfoliated nanocomposites.These nanocomposites show enhanced properties as compared to microcomposites and pristine polymer. However, biodegradation and hydrolytic degradation of PLA in the presence of nanoclays has been investigated to a small extent. 

Multiwalled CNTs were also used to improve the mechanical properties of polylactide-caprolactone copolymer. The composite with only 2 wt% of MWCNTs showed 100% improvement in the elastic modulus and a 160% enhancement in tensile strength [64]. Others showed significant reinforcement in bofli compressive modulus (74%) and flexural modulus (69%) with only 0.05 wt% of single-walled CNTs [65]. These results demonstrate favorable cytocompatibility for potential use as scafrbld for bone tissue engineering applications. 

Y. Tabata and Y. Ikada, Protein precoating of polylactide microspheres containing a lipophilic immunopotentiator for enhancement of macrophage phagocytosis and activation. Pharm. Res., 6(4), 296-301 (1989). 

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