(615f) Magnetic Cellulose Nanocomposites Coated By Benzalkonium Chloride for Adsorption Study and Antibacterial Activity Against L. Monocytogenes

Magnetic nanocomposites have gained much interest in promising applications, including their utilization in food safety and in antibacterial treatments against hazardous pathogens. In this work, we synthesized superparamagnetic iron oxide nanoparticles on the surface of cellulose nanocrystals (CNC-Fe₃O₄) using a co-precipitation technique. Further functionalization of the prepared nanocomposites was carried out with benzalkonium chloride (BC)-one of the most popular quaternary ammonium compounds widely recognized for its broad-spectrum antimicrobial properties. This research investigated the capability of BC in interacting with the magnetic nanoparticles through adsorption and desorption studies. Further, it examined the antibacterial activity of the as-prepared CNC-Fe₃O₄ against Listeria monocytogenes, one of the most important foodborne pathogens causing severe health risks.

XRD studies confirmed magnetite (Fe₃O₄) as the main crystalline phase, which presents a cubic spinel structure. TEM and SEM revealed spherical-shaped nanoparticles up to 20 nm in size and rod-shaped CNC, which agreed with the general size and shape obtained through co-precipitation methods. Magnetic behavior was superparamagnetic at room temperature, as observed by VSM analysis, which indicated high values for saturation magnetization. Adsorption experiments confirmed that good adsorption occurred on CNC@Fe₃O₄, and within 36 hours, equilibrium was reached. Further, the antibacterial activity of functionalized benzalkonium chloride nanocomposites, BC@CNC-Fe₃O₄, was investigated by the standard disk diffusion method. The results demonstrated notable inhibition against Listeria monocytogenes, leading to enhanced antibacterial activities compared with the control samples. Such an improvement in activities is because of the synergistic interaction between magnetic nanoparticles and benzalkonium chloride that further enhances antimicrobial action while offering the possibility of magnetically recovering and reutilizing the nanocomposite. These findings give insight into the development of advanced antimicrobial materials for food safety and biomedical applications in which antibiotic resistance and pathogen control in food systems are pressing concerns.