Novel antimicrobial chitosan–cellulose composite films bioconjugated with silver nanoparticles

• Silver nanoparticles were bioconjugated with the chitosan/cellulose films.
• Amide bonds formed between chitosan and silver nanoparticles.
• The composite films showed significantly improved antimicrobial activities.

Cellulose-based membranes have emerged as an attractive alternative to non-biodegradable petrochemical materials. An important drawback, however, is that cellulose-based membranes are prone to biofouling. Silver nanoparticles (AgNPs) encapped with polyacrylic acid were conjugated with the chitosan/cellulose composite films to enhance the antimicrobial activities. Using the 1-ethyl-3-(3-dimethylaminopropyl) carbodii-mide hydrochloride and N-hydroxysuccinimide as biocoupling agents, AgNPs with an average size of 9 nm were distributed evenly in the film without agglomeration. The presence of AgNPs in the chitosan/cellulose–AgNPs composite films was further confirmed by X-ray diffraction measurements. Fourier transform infrared spectroscopy analysis supported the presence of amide bonds between the primary amino groups of chitosan and the carboxylic residues of coordination to silver nanoparticles. The antimicrobial properties of the chitosan/cellulose and chitosan/cellulose–AgNPs composite films were determined using the disk diffusion tests with Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). As compared to the chitosan/cellulose composite films, the chitosan/cellulose–AgNPs composite films showed significantly improved antimicrobial activities.