Prohibiting the Growth of Candida albicans Using Nitric Oxide

Candida albicans is a part of the normal flora of the mucosal membrane and female genital tract but the overgrowth of this opportunistic pathogen is a concern especially amongst immunocompromised patients.  Cells employed in the innate immune response utilize nitric oxide (NO) along with other cytotoxins to prevent the overgrowth of C. albicans.  In cases of severe colonization, exogenous sources of NO could supplement the body’s natural defense against this pathogen.  In this work, an NO donating biocompatible material was employed and showed toxicity against C. albicans. The polyurethane based material rapidly releases cytotoxic quantities of NO upon exposure to mW levels of visible light via the photolysis of metal coordinated NO from [Mn(PaPy3)(NO)](ClO4) molecules entrapped in silica xerogel particles. The particle size serve to immobilize the NO donor within the polyurethane film and provide an adequate degree of solvation for NO release from [Mn(PaPy3)(NO)](ClO4).The antimicrobial property of NO-releasing films is demonstrated by illuminating films placed on top of a 1.1 mm thick layer of soft agar inoculated with 4x10^8 CFU of C. albicans spread on a petri dish containing nutrient rich agar. After incubating, the plates are assessed for the extent of growth inhibition.  Varying the amount of incorporated [Mn(PaPy3)(NO)](ClO4) and the duration of illumination illustrates dose-dependent killing of microbes. The plate with the highest dose displays a complete eradication of colonies under the site of application. The results of this work suggest that the NO-releasing material could be an effective treatment option for wounds infected by C. albicans.