Electrospinning of zein/propolis nanofibers; antimicrobial properties and morphology investigation

In this work, for the first time, zein nanofiber mats loaded with ethanol extracts propolis (EEP) were successfully produced. Raw propolis was extracted by ethanol 70% and total flavonoid content was estimated by aluminum chloride colorimetric method. The anti-microbial activity of the EEP was investigated and compared with amoxicillin via zone of inhibition test against various microorganisms included gram-positive: Staphylococcus aureus, Staphylococcus epidermidis, gram-negative: Escherichia coli, Salmonella enterica, Pseudomonas aeruginosa and fungus: Candida albicans. The EEP showed activity only against gram-positive types and fungus, whereas no activity was observed against gram-negative types. Electrospun zein nanofiber was obtained from 70% ethanolic solutions included different content of zein, 15–40 wt.%. The SEM images revealed a smooth ribbon-like morphology for zein nanofibers without any beads in zein content more than 25 wt.%. As well, the SEM images of electrospun zein nanofibers containing different content of propolis (0–40 wt.% based on the zein content) disclosed the increase in the average size of fibers with propolis content from 264 to 419 nm. This increasing was more probably due to the reduction in ionic conductivity of zein solutions with propolis content. The proteinic nature of zein along with the antimicrobial activity and the herbal nature of the propolis make the obtained mats promising candidate for more evaluation in wound healing study.