Antimicrobial activity enhancement of chitosan nanoparticles/natural rubber composite foam

This study aims to develop biodegradable antibacterial natural rubber (NR) composite foams by incorporating chitosan (CS) and chitosan nanoparticles (CSNPs), with electron beam (EB) irradiation used as a clean crosslinking method. While NR foams offer excellent elasticity and comfort, their vulnerability to microbial contamination and reliance on chemical crosslinkers limit their application in biomedical and hygiene-related products. To address this, CSNPs were synthesized via ionotropic gelation, yielding particles with a size of 200-300 nm, as confirmed by transmission electron microscopy (TEM). Three types of NR foams were fabricated from natural rubber latex (NRL), which were pure NR foam (NRF), CS-filled foam (CS/NRF), and CSNP-filled foam (CSNPs/NRF). All samples were vulcanized using electron beam (EB) irradiation at 200 kGy. Scanning electron microscopy revealed a porous structure in all foams, with improved dispersion and pore integrity in CSNPs/NRF compared to CS/NRF. The 25 % indentation hardness test showed acceptable mechanical performance for practical use. Antibacterial tests against Staphylococcus aureus and Escherichia coli demonstrated significantly enhanced activity in CSNPs/NRF, attributed to the increased surface area and better distribution of CSNPs. Additionally, all foam types exhibited biodegradability in soil, with visible microbial colonization and gradual weight loss over time. These findings highlight the potential of CSNP-reinforced NR foams, crosslinked by electron beam (EB) irradiation, as eco-friendly antibacterial materials for biomedical and hygienic applications.