In vitro and in vivo evaluation of poly-3-hydroxybutyric acid-sodium alginate as a core-shell nanofibrous matrix with arginine and bacitracin-nanoclay complex for dermal reconstruction of excision wound.

The protective layer of the body, the skin is often prone to damage due to several factors like trauma, accidents, stress and hazardous exposure. This requires the skin to regenerate itself which is a finely regulated process. To hasten the process and prevent further damage, the dressing material is of prime importance. Herein, we fabricated poly-3-hydroxybutyric acid (P)-sodium alginate (S)-(core-shell) nanofibrous matrix as protective scaffold for the skin tissue regeneration in excision wound model. The arginine (A) and layered double hydroxides-bacitracin (LB) were incorporated into the core and shell of the nanofibrous matrix using co-axial electrospinning. The core-shell nanofibers assist in the synergistic, controlled delivery of L-arginine, and bacitracin with major role in the protein synthesis, cell signaling and infection control at wound site respectively. In vitro biocompatibility was confirmed by testing on dermal fibroblasts. Furthermore, in vivo studies revealed the synergistic effect of both the components in active healing of wounds. The biochemical, histochemical and immunohistochemical studies reveal that the arginine loaded scaffold aided cellular migration and proliferation. These results suggest that the simultaneous existence of the drug bacitracin-nano clay complex and L-arginine in the shell and core respectively has conferred interesting dynamic properties to the scaffold towards wound healing.

Toxic behavior of silver and zinc oxide nanoparticles on environmental microorganisms.

Silver and zinc oxide nanoparticles (Ag and ZnO NPs) are widely used as antimicrobial agents. However, their potential toxicological impact on environmental microorganisms is largely unexplored. The aim of this work was to investigate the sensitivity and adaptability of five bacterial species isolated from sewage towards Ag and ZnO NPs. The bacterial species were exposed to increasing concentration of nanoparticles and the growth inhibitory effect, exopolysaccharides (EPSs) and extracellular proteins (ECPs) productions were determined. The involvement of surface charge in nanoparticles toxicity was also determined. The bacterial species were constantly exposed to nanoparticles to determine the adaptation behavior toward nanoparticles. The nanoparticles exhibited remarkable growth inhibitory effect on tested bacterial species. The toxicity of nanoparticles was found to be strongly dependent on surface charge effects. Though, these organisms are highly sensitive to Ag and ZnO NPs, the continuous exposure to these nanoparticles leads to moderate adaptation of bacterial species and the adapted bacterial species convert the highly toxic nano form to less toxic microform. Finally we predict that the continuing applications of nanoparticles in consumer products may lead to the development of nanoparticles resistant bacterial strains in future.