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.