CuNPs-magadiite/chitosan nanocomposite beads as advanced antibacterial agent: Synthetic path and characterization

In this work, an inorganic-organic nanocomposite was prepared by combining copper exchanged-magadiite (Cu-magadiite) with chitosan. The synthesis was carried out by direct dispersion of the Cu-magadiite in the chitosan matrix. The mixture obtained is shaped into beads with an average diameter of about 1-1.2 mm. These beads were then contacted with a solution of NaBH4 in order to reduce loaded copper ions into copper nanoparticles species. The resulting nanocomposite (Cu-NPs-magadiite/chitosan) was characterized by XRD, FTIR, SEM, TG, UV-visible DR and EDX analysis. The results show that the magadiite was completely exfoliated confirming the formation of the organic-inorganic composite. Indeed, the encapsulation of magadiite was confirmed by the SEM images, which is presented as micron free aggregates included in the cavities of a continuous polysaccharide matrix. Otherwise, they confirm also the formation of CuNPs which are probably immobilized inside the magadiite-chitosan solid matrix. The antibacterial activity against E. coli and S. aureus was highlighted by the disc inhibition method and the minimum inhibitory concentration (MIC) was determined. The CuNPs-magadiite/chitosan nanocomposite showed a very efficient bactericidal effect against both pathogen bacteria. Additionally, the MIC values obtained for nanocomposite are of 0.25 μg/L against S. aureus and of 0.50 μg/L against E. coli.