Nanocellulose-based aerogels decorated with Ag, CuO and ZnO nanoparticles: Synthesis, characterization and the antibacterial activity

Abstract

In this work, porous bacterial cellulose aerogels (BCA) were prepared by 1-step (BCA-1) and 3-step (BCA-3) exchange of solvent inside the bacterial cellulose hydrogel (0.65 %) with tertiary butyl alcohol followed by freeze-drying. BCA-3 was used as a template for Ag, CuO, and ZnO nanoparticles by reducing the corresponding salt using sodium borohydride (NaBH4) as a reducer agent. The silver nanoparticles (Ag NPs) were grown onto the BCA-3 scaffold (Ag/BCA-3) by adjusting the amount of AgNO3 with two different processes. Similarly, CuO and ZnO cellulosic nanocomposites (CuO/BCA-3 and ZnO/BCA-3) were fabricated by the optimized amount (0.1 M) and method (method-2). Aerogel and metal nanoparticle composites were characterized by Brunauer-Emmett-Teller (BET); UV–visible spectrophotometry (UV–Vis); X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR); Scanning electron microscopy (SEM); Energy dispersive spectroscopy (EDS); and Transmission electron microscopy (TEM) analysis. Results showed that the web-like entangled structures of aerogels have specific surface areas as high as 87–97 m2g−1. Ag/BCA-3 and CuO/BCA-3 exhibited a spherical morphology of NPs with an average particle size of about 50 nm and 10 nm, respectively. ZnO/BCA-3 resulted in hexagonal morphology with around 50 nm. The metal nanocomposites showed antibacterial activity against Klebsiella pneumonia (gram-negative) and Staphylococcus aureus (gram-positive) bacteria.