Bio-derived and biocompatible poly(lactic acid)/silk sericin nanogels and their incorporation within poly(lactide-co-glycolide) electrospun nanofibers

Bio-derived and biocompatible nanogels based on poly(lactic acid) (PLA) and silk sericin (SS) have been synthesized for the first time. Low molecular weight PLA and SS were first modified using allyl glycidyl ether to create a PLA macromonomer and an SS multifunctional crosslinker (PLAM and SSC, respectively), as confirmed by NMR and FTIR spectroscopies. Nanogels were synthesized from PLAM/SSC and N′,N-methylene bisacrylamide (N′,N-mBAAm) as an additional bifunctional crosslinker via classical free-radical polymerization at systematically varied levels of additional crosslinking (0, 0.5, 1.0, 1.5 and 2.0 w/w% N′,N-mBAAm). Higher crosslink densities led to smaller nanogel particles with reduced accumulative drug release. Crosslinked PLAM/SSC nanogels at 0.5% N′,N-mBAAm with 400–500 nm diameter particles were shown to be non-toxic to the normal human skin fibroblast cell line (NHSF) and selected for incorporation within poly(lactide-co-glycolide) (PLGA) electrospun nanofibers. These embedded nanogel-PLGA nanofibers were non-toxic to the NHSF cell line and exhibited higher cell proliferation than pure PLGA nanofibers, due to their higher hydrophilicity induced by the PLAM/SSC nanogels. This work shows that our new crosslinked-PLAM/SSC nanogels have potential for use not only in the field of drug delivery but also for tissue regeneration by embedding them within nanofibers to create hybrid scaffolds

In Situ Compatibilized Blends of PLA/PCL/CAB Melt-Blown Films with High Elongation: Investigation of Miscibility, Morphology, Crystallinity and Modelling

Ternary-blended, melt-blown films of polylactide (PLA), polycaprolactone (PCL) and cellulose acetate butyrate (CAB) were prepared from preliminary miscibility data using a rapid screening method and optical ternary phase diagram (presented as clear, translucent, and opaque regions) as a guide for the composition selection. The compositions that provided optically clear regions were selected for melt blending. The ternary (PLA/PCL/CAB) blends were first melt-extruded and then melt-blown to form films and characterized for their tensile properties, tensile fractured-surface morphology, miscibility, crystallinity, molecular weight and chemical structure. The results showed that the tensile elongation at the break (%elongation) of the ternary-blended, melt-blown films (85/5/10, 75/10/15, 60/15/25 of PLA/PCL/CAB) was substantially higher (>350%) than pure PLA (ca. 20%). The range of compositions in which a significant increase in %elongation was observed at 55–85% w/w PLA, 5–20% w/w PCL and 10–25% w/w CAB. Films with high %elongation all showed good interfacial interactions between the dispersed phase (PCL and CAB) and matrix (PLA) in FE-SEM and showed improvements in miscibility (higher intermolecular interaction and mixing) and a decrease in the glass transition temperature, when compared to the low %elongation films. The decrease in Mw and Mn and the formation of the new NMR peaks (1H NMR at 3.68–3.73 ppm and 13C NMR at 58.54 ppm) were observed in only the high %elongation films. These are expected to be in situ compatibilizers that are generated during the melt processing, mostly by chain scission. In addition, mathematical modelling was used to study the optimal ratio and cost-effectiveness of blends with optimised mechanical properties. These ternary-blended, melt-blown films have the potential for use in both packaging and medical devices with excellent mechanical performance as well as inherent economic and environmental capabilities