Alginate/gum acacia bipolymeric nanohydrogels--promising carrier for zinc oxide nanoparticles

Zinc oxide nanoparticles (ZnO nps) are known to be effective against a wide array of microorganisms. At nanoscale, they have higher toxicity and they need to be rendered less toxic and more biocompatible. To achieve this, ZnO nps were incorporated in nanohydrogel particles made out of sodium alginate/gum acacia and cross-linker glutaraldehyde in order to ensure their gradual and sustained release instead of burst release, and hence lowering their toxicity. The particles synthesized were in the nano-range, i.e., 70-100 nm size and their in vitro release studies indicated that release of upto 68% of ZnO nps was prolonged to over 2 weeks following the Higuchi model. Cytotoxicity studies on vero cell line (African green monkey kidney cell line) revealed that toxicity of ZnO nps-loaded nanohydrogels was substantially lower as compared to ZnO nps. At the same time, it demonstrated desired level of antibiotic activity against Pseudomonas aeruginosa, an antibiotic resistant microbial model. In conclusion, this work led to successful preparation of novel formulation of ZnO incorporated in nanohydrogels that are not only safer but also retain adequate antibacterial activity due to their ability for gradual and sustained release of the active constituent.