Combatting fungal biofilm formation by diffusive release of fluconazole from heptylamine plasma polymer coating

A drug-eluting coating applied onto biomedical devices and implants is an appropriate way to ensure that an inhibitory concentration of antimicrobial drugs is present at the device surface, thus preventing surface colonization and subsequent biofilm formation. In this study, a thin polymer coating was applied to materials, and it acted as a drug-delivery reservoir capable of surface delivery of the antifungal drug fluconazole to amounts up to 21 μg/cm². The release kinetics into aqueous solution were quantified by UV spectroscopy and conformed to the Ritger-Peppas and Korsmeyer-Peppas model. Complementary microbiological assays were used to determine effectiveness against Candida albicans attachment and biofilm formation, and against the control heptylamine plasma polymer coating without drug loading, on which substantial fungal growth occurred. Fluconazole release led to marked antifungal activity in all assays, with log 1.6 reduction in CFUs/cm². Cell viability assays and microscopy revealed that fungal cells attached to the fluconazole-loaded coating remained rounded and did not form hyphae and biofilm. Thus, in vitro screening results for fluconazole-releasing surface coatings showed efficacy in the prevention of the formation of Candida albicans biofilm.