Microwave Crosslinked Chitosan/Green Fluorescent Carbon Nanoparticles Film: Comprehensive Characterisation and Antimicrobial Performance

Conventional crosslinkers used to reduce the swelling of chitosan films are prone to toxicity. Fluorescent carbon nanoparticles, on the other hand, present a safer alternative. This study aims to crosslink microwave-synthesised green fluorescent carbon nanoparticles (GFCNPs) with high quantum yield (44%) and chitosan film via solvent casting (CHT/GFCNPs). The particle size distribution of GFCNPs predominantly ranged from 5 nm to 15 nm. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) analyses indicated the presence of graphite. Attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy detected various functional groups that enabled crosslinking. The CHT/GFCNPs exhibited significantly lower swelling (500%) compared to chitosan film (2300%). Preliminary findings of antibacterial activity demonstrated the effects of the compounds on bacteria with different cell wall structures, namely Gram-positive and Gram-negative bacteria. The CHT/ GFCNPs showed potential antibacterial activity against Staphylococcus aureus, a Grampositive bacteria, compared to Escherichia coli, a Gram-negative bacteria.