Investigation of optical, structural, morphological and antimicrobial properties of carboxymethyl cellulose capped Ag-ZnO nanocomposites prepared by chemical and mechanical methods

• Novel Ag-ZnO nanocomposites were synthesized by chemical and mechanical methods.
• Spherical Ag NPs were deposited on ZnO NPs surface in the presence of CMC biopolymer.
• Ag-ZnO nanocomposites contained up to 0.64 wt.% Ag NPs with diameter of 3–21 nm.
• A mechanism for obtaining CMC capped Ag-ZnO NPs by chemical synthesis was proposed.
• Ag-ZnO and ZnO nanomaterials exhibited good antimicrobial and antibiofilm activity.

This study reports on preparation and investigation of novel Ag-ZnO nanocomposites with antimicrobial activity. Carboxymethyl cellulose (CMC) capped Ag-ZnO nanoparticles (NPs) were synthesized by chemical (CD) and mechanical deposition (MD) of Ag NPs on ZnO NPs. The samples were investigated by UV–Vis spectroscopy, FTIR, XRD, DLS, SEM, EDX, WDXRF and TEM analyses. The antimicrobial activity was assessed against a wide range of pathogenic microorganisms in planktonic and adherent state. Ag-ZnO nanocomposites exhibited maximum 0.64 wt.% spherical Ag NPs deposited on hexagonal prism ZnO NPs with single surface plasmon absorption band ranging 398–424 nm. The mechanism for obtaining CMC capped Ag-ZnO NPs by chemical synthesis was proposed. Ag-ZnO nanocomposites yielded average crystallite size of 56.1–64 nm, mean effective diameter of 388–427 nm, polydispersity of 0.193–0.286, and a bimodal volume-weighted particle size distribution. All nanomaterials exhibited good antimicrobial activity against planktonic and biofilm growing bacteria.

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