Slow zinc release from carboxymethylcellulose gels filled with humic zinc oxide nanocomposites

The study is focused on characterization of humic zinc oxide nanocomposites and their potential application in wound healing as antibacterial agent. Zinc oxide nanoparticles were synthesized with varying concentrations of humic substances (HS) and analyzed using PXRD, TEM, SEM and UV-Vis techniques. The nanoparticle sizes based on the PXRD data decreased ranged from 50 to 15 nm along with an increase in humic ligand concentration. TEM images revealed that the star-shaped aggregates of 200–500 nm ZnO particles were formed in the absence of HS, whereas the presence of humic ligands led to shapeless smaller particles ranging from 20 to 200 nm. UV-Vis spectra showed increasing of zinc oxide band gap caused with an rise of HS concentration. The band gap of ZnO nanoparticles increased from 3.19 eV to 3.40 eV as the concentration of HS increased up to 15 g/L. The synthesized ZnO–HS nanocomposites were used for filling in the hydrogels of carboxymethylcellulose (CMC). The release studies of zinc ions from the gel into different buffers were conducted to imitate wound conditions. The measurements of Zn concentrations over time in buffer showed a gradual release over time making these gels potentially suitable for long-term wound treatment.