Impregnation of silver nanoparticles into bacterial cellulose for antimicrobial wound dressing

Bacterial cellulose was produced by Acetobacter xylinum (strain TISTR 975). Bacterial cellulose is an interesting material for using as a wound dressing since it provides moist environment to a wound resulting in a better wound healing. However, bacterial cellulose itself has no antimicrobial activity to prevent wound infection. To achieve antimicrobial activity, silver nanoparticles were impregnated into bacterial cellulose by immersing bacterial cellulose in silver nitrate solution. Sodium borohydride was then used to reduce the absorbed silver ion (Ag+) inside of bacterial cellulose to the metallic silver nanoparticles (Ag0). Silver nanoparticles displayed the optical absorption band around 420 nm. The red-shift and broadening of the optical absorption band was observed when the mole ratio of NaBH4 to AgNO3 (NaBH4:AgNO3) was decreased, indicating the increase in particle size and particles size distribution of silver nanoparticles that was investigated by transmission electron microscope. The formation of silver nanoparticles was also evidenced by the X-ray diffraction. The freeze-dried silver nanoparticle-impregnated bacterial cellulose exhibited strong the antimicrobial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive).