Preparation and characterization of shellac/PVP iodine blend as antimicrobial film patch

Shellac is a purified resinous secretion of lac insects which are mostly cultivated in host trees in Thailand. As of nature origin and some attractive advantages such as low water permeability and good film forming property, shellac could be used for various pharmaceutical and agricultural applications. In the present study, shellac was applied as a matrix forming agent for antimicrobial film patch. It was blended with polyvinyl pyrrolidone iodine (PVPI) and casted into the films. The blend films were then characterized for physicochemical properties and antimicrobial property against Staphylococcus aureus. The result demonstrated that all films were easily prepared. However, the mechanical properties, melting and solubility were depended on the composition of blended films. The percent elongation was increased as increasing the fraction of shellac in blend films, suggesting the more flexibility of shellac. The solubility of blend films was decreased after addition of PVPI. The result was agreed well with the increment of melting temperature. For antimicrobial property, the films containing 30% w/w or more of PVPI clearly demonstrated inhibition zone of S. aureus. The inhibition zone was increased from 7.4 to 13.0 mm after increasing the percentage of PVP iodine from 30% to 50 % w/w. In conclusion, shellac could be a promising polymer for fabrication of antimicrobial film patch.