Enhanced Antibacterial and Photocatalytic Performance of Synergistic Graphene/Cellulose/Chitosan–Ag Nanocomposites

Abstract

In the current research, graphene and cellulose nanocrystals (CNCs) loaded with silver nanoparticles were synthesized using the hydrothermal method with different mass ratios (G:CNC:CS). The composite GC2 (1:0.2:0.2) (MIC = 6.1 µg·mL−1) and GC3 (1:0.3:0.3) (MIC = 1.8 µg·mL−1) exhibited the maximum antibacterial activity against Staphylococcus aureus subsp. aureus ATCC BAA-977 and Pseudomonas aeruginosa, respectively. The antibacterial performance underscores the complex interplay between the compositional attributes of GC2 and GC3, and the unique susceptibility profiles of different bacterial strains. The antibacterial mechanism was proposed to understand the antibacterial activity process. Ag+ cations and reactive oxygen species (ROS) formed with the composite materials are responsible for disrupting interactions with the bacterial cell wall via transmembrane proteins. Eriochrome Black T exhibited the highest photocatalytic degradation efficiency (~90% under UV), followed by Congo Red, which also showed substantial removal across all irradiation conditions. In contrast, Bisphenol A and tetracycline displayed comparatively lower degradation efficiencies, particularly under UV light. Overall, the degradation trend for all pollutants followed the order: UV > solar > visible irradiation.