Immobilization of triclosan and erythrosine in layer-by-layer films applied to inactivation of microorganisms.

The use of layer-by-layer (LbL) deposition technique allows materials, such as drugs, to be self-assembled in multilayers with other electrolytes by combining their properties in a nanostructured system. Triclosan (TCS) is commonly used as a drug because of its bactericidal action, while erythrosine (ERY) has been used as a photosensitizer in photodynamic therapies because of its high light absorptivity in the visible region of the electromagnetic spectrum. The major advantage of investigating systems immobilized in LbL films is the benefit of characterizing the interaction through available substances in solid state techniques. It was possible to immobilize in LbL films, ERY, and ERY + TCS. The results show that the growth of the films was linear, indicating the deposition of the same amount of material from the first bilayer without substrate interference. The release analysis showed slow kinetics, which occurred more rapidly for ERY LbL films, probably due to apparent activation energy, which were higher for films with TCS. The combination of TCS, ERY, and laser light (532 nm) for photodynamic inactivation of the fungus Candida albicans was analyzed, and the results were promising for future studies in applications, such as coating surfaces of dental implants.

Incorporation of triclosan and acridine orange into liposomes for evaluating the susceptibility of Candida albicans.

Candida albicans is responsible for many of the infections affecting immunocompromised individuals. Although most C. albicans are susceptible to antifungal drugs, uncontrolled use of these drugs has promoted the development of resistance to current antifungals. The clinical implication of resistant strains has led to the search for safer and more effective drugs as well as alternative approaches, such as controlled drug release using liposomes and photodynamic inactivation (PDI), to eliminate pathogens by combining light and photosensitizers. In this study, we used layer-by-layer (LBL) assembly to immobilize triclosan and acridine orange encapsulated in liposomes and investigated the possibility of controlled release using light. Experiments were carried out to examine the susceptibility of C. albicans to PDI. The effects of laser irradiation were investigated by fluorescence microscopy, atomic force microscopy, and release kinetics. Liposomes were successfully prepared and immobilized using the self-assembly LBL technique. Triclosan was released more quickly when the LBL film was irradiated. The release rate was approximately 40% higher in irradiated films (fluence of 15J/cm2) than in non-irradiated films. The results of the susceptibility experiments and surface morphological analysis indicated that C. albicans cell death is caused by photodynamic inactivation. Liposomes containing triclosan and acridine orange may be useful for inactivating C. albicans using light. Our results lay the foundation for the development of new clinical strategies to control resistant strains.

Spray layer-by-layer films for photodynamic inactivation.

BACKGROUND: A novel approach for photodynamic inactivation of Candida albicans is proposed. This method consists of realizing inactivation using ultraviolet light (254nm) combined with spraying layer-by-layer films of acridine orange. METHODS: To evaluate the effectiveness of the approach, the C. albicans were immobilized on quartz slices and covered with the spray layer-by-layer films. The fungi were analyzed using experiments to determine cell viability, as well as by fluorescence and atomic force microscopy. RESULTS: Viability analysis of C. albicans after photodynamic inactivation assisted by the films indicates cell death. The extent of cell death increases as the number of film layers increases. Fluorescence and atomic force microscopy analyses corroborated the cell death of C. albicans, which is posited to be due to damages to the fungi cell wall. CONCLUSIONS: Our approach has the potential to be used as an alternative for photodynamic inactivation of C. albicans. In addition, this method could be used in clinical procedures, such as for the decontamination of medical devices.