RESUMO
The present study describes the development of a chlorhexidine long-term drug delivery system using starch as a biodegradable polymer base. Three batches of thermoplastic starch films, containing starch particles/nanoparticles and chlorhexidine (CHX), were manufactured by casting. Morphological characterization showed an irregular surface with particles incorporated with chlorhexidine agglomerated in a starch matrix. Nanoindentation showed that the control film (without chlorhexidine) presented a more plastic and rigid behavior in relation to the films containing CHX. CHX was partially bounded to starch and prevented starch crystallization. Starch nanoparticles formed by precipitation were observed through transmission electron microscopy. By incorporating CHX into the solution, the nanoparticles presented different morphology, suggesting absorption of the drug. In vitro drug release was observed for 21 days by UV-vis spectrophotometry and released CHX amounted up to 19 mg/100 ml. Films presented microbiological potential for inhibiting Staphylococcus aureus growth as evaluated by the disk diffusion test in agar. It has been concluded that the developed film met the main requirements for a drug delivery system and that it is possible to be produced from a simple, cheap and reproduceable process.