Antibacterial polypeptide-bioparticle for oral administration: Powder formulation, palatability and in vivo toxicity approach.

The upsurge of bacterial resistance to conventional antibiotics turned a well-recognized public health threat. The need of developing new biomaterials of effective practical use in order to tackle bacterial resistance became urgent. In this study, a submicrometric bioparticle of known antibacterial activity was produced in powder form with suitable texture and appealing characteristics for effective oral administration. Through complex coacervating a natural-source antimicrobial polypeptide with chitosan-N-arginine and alginate, the bioactive polypeptide was physically incorporated to the bioparticle whose structure positively responds to the pH variations found in gastrointestinal tract. The powder formulation presented high palatability that was evaluated using fish as in vivo animal model. A thorough survey of the fish intestinal tissues, following a systematic oral administration, revealed high penetration potential of the biomaterial through epithelial cells and deeper intestine layers. Despite, no cytotoxic effect was observed in analyzing the tissues through different histology methods. The absence of intestinal damage was corroborated by immune histochemistry, being the integrity of epithelial motor myosin Vb and related traffic proteins preserved. Hematology further endorsed absence of toxicity in blood cells whose morphology was evaluated in detail. The study evidenced the applicability potential of a new biomaterial of appealing and safe oral administration of antibacterial polypeptide.

Physicochemical properties of methylcellulose and dodecyltrimethylammonium bromide in aqueous medium.

Interactions between uncharged polymers and cationic surfactants are considered weaker than interactions with the anionic analogues. This work describes the binding occurring between methylcellulose (MC) and the cationic surfactant DTAB in aqueous medium. In the absence of salt, MC-DTAB exhibits a maximum in hydrodynamic radius, R(h,slow), with the increase in the surfactant concentration. Otherwise, in presence of salt the MC-DTAB system shows only a linear increase of R(h,slow). CAC is lower than the CMC, which is taken as an evidence of binding between the cationic surfactant and neutral polymer that induces the aggregation process. Static light scattering, rheology and micro-DSC results highlight the hydrophobic MC-DTAB association. Salt-out and the salt-in effects were observed in presence of DTAB, with a clear transition at concentration values close to the CMC, as judged from rheological and micro DSC measurements. Indeed, DTAB affects both the pattern of the sol-gel transition and the gel strength.