In vitro physiological and antibacterial characterization of ZnO nanoparticle composites in simulated porcine gastric and enteric fluids

BACKGROUND: Diarrhea in piglets is one of the main causes of animal death after weaning; zinc oxide (ZnO) has been used in high doses for the control of this sickness. The aim of this study was to determine the physicochemical properties of ZnO nanoparticles synthesized and immobilized on a chitosan/alginate (CH/SA) complex and investigate the antimicrobial activity and in vitro release profile of zinc (Zn(2+)) from these new compounds. The ZnO nanoparticles composites were prepared and combined with CH/SA or CH/SA and sodium tripolyphosphate (TPP). The structure and morphology of the composites were analyzed by characterization methods such as X-ray diffraction, FTIR spectroscopy, thermogravimetric analysis, atomic absorption spectrophotometry and scanning electron microscopy. RESULTS: The crystallite size of ZnO nano was 17 nm and the novel ZnO composites were effective in protecting ZnO in simulated gastric fluid, where Zn(2+) reached a concentration six-fold higher than the levels obtained with the unprotected commercial-zinc oxide. In addition, the novel composites suggest effective antimicrobial activity against Escherichia coli and Staphylococcus aureus. CONCLUSIONS: The results described herein suggest that the novel nano composites may work as an alternative product for pig feeding as verified by the in vitro assays, and may also contribute to lower the zinc released in the environment by fecal excretion in animals waste.