Characterization of nanosilver antibacterial bacterial cellulose composite membranes coated with montmorillonite and their potential application in food packaging.

Bacterial cellulose (BC) is a natural, renewable polymer material with an ultrafine nanonetwork structure. However, BC has limited applications in food packaging and medical materials because of its lack of antibacterial properties. To expand the applications of BC, a new BC composite membrane was synthesized via an ex situ method. The BC membrane was first immersed in 100 mL of deionized water containing 3 mg of AgNO₃ for 24 h to incorporate silver nanoparticles (AgNPs). The BC-Ag composite was immersed in a 2 wt% montmorillonite (MMT) solution for 24 h to prepare the BC-Ag-MMT composite membrane. The structure and antibacterial properties of the composite were then examined. Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the successful synthesis of the BC-Ag-MMT composite membrane. The results revealed that the addition of AgNPs and MMT resulted in a significant decrease in porosity (13.23 ± 1.12 %), water vapor transmission rate (735.12 ± 12.55 g/(m·day)), and oxygen permeability (2.28 ± 0.29 g/(s·mPa)) while increasing the membrane thickness (0.89 ± 0.08 mm). The incorporation of MMT into BC notably improved the thermal stability of the membrane and further influenced its porosity. The antibacterial activity was evaluated via the inhibition zone method. The BC-Ag-MMT composite membrane exhibited antibacterial activity against Salmonella paratyphi A, Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella enterica. These findings demonstrated that the BC-Ag-MMT composite membrane possesses exceptional physical and chemical properties, mechanical strength, and antibacterial efficacy. The composite membrane holds significant potential for applications in food packaging.