Detection of 2-ethyl-1-hexanol and its modulating effect in biofilm of Fusarium oxysporum.

In immunocompetent individuals, Fusarium spp. stands out as the causative agent of onychomycosis, among the non-dermatophyte molds. Despite evidence indicating that Fusarium oxysporum organizes itself in the form of a biofilm causing onychomycosis, there is little literature on the etiopathogenesis of the biofilm on the nail, specifically the signaling molecules present, known as quorum sensing (QS). Thus, this study detected the presence of a molecule related to QS from the ex vivo biofilm of F. oxysporum on human nail and investigated its effect on preformed biofilm in vitro. The detection and physicochemical characterization of a QS molecule, from the extracellular matrix (ECM), was carried out by Fourier transform infrared (FTIR) spectroscopy with an attenuated total reflectance (ATR) accessory and by headspace gas chromatography coupled to mass spectrometry (GC-MS) analyses. Determination of viable cells, cell activity, total biomass, ECM components and scanning electron microscopy (SEM) were performed to evaluate the influence of the QS molecule on the in vitro biofilm of F. oxysporum. The beginning, in the ex vivo biofilm of F. oxysporum on human nails, the volatile organic compound 2-ethyl-1-hexanol (2EH) was detected as a component of QS. Thereafter in vitro analyses, synthetic 2EH was able to modulate the biofilm by stimulating its filament, increasing total biomass and ECM production in terms of total carbohydrates, but with a reduction in total proteins and nucleic acids. We thus evidence, for the first time, the presence of 2EH in the biofilm of F. oxysporum, developed on the human nail, and the in vitro action of this compound as a QS molecule.

PEG-coated vesicles from Pluronic/lipid mixtures for the carrying of photoactive erythrosine derivatives.

Liposomes are very attractive membrane models and excellent drug delivery systems. Concerning their drug delivery aspects, the mixing liposomes with biocompatible copolymers allows for stability and the incorporation of several drugs. We developed PEG coated vesicles from the mixture of DPPC and F127 Pluronic copolymer to obtain long-circulating nanoparticles (mixed vesicles). We employed an innovative process previously developed by us: a small amount of F127 mixed in DPPC, thin film preparation, followed by hydration (lipids plus F127) using a bath sonicator cleaner type, forming unilamellar spherical vesicles with diameter ∼100 nm. The formed PEG coated vesicles were incorporated with the xanthene dye Erythrosine B (ERY), and its ester derivatives as photosensitizers (PS) for photodynamic proposes. The F127/DPPC mixed vesicles promoted a higher PS incorporation, and with better thermal and kinetic stability, at least 60 days, when compared to conventional DPPC liposome. The binding constant and quenching analysis revealed that with a higher PS hydrophobicity, PS affinity increases toward the nanoparticle and results in a deeper PS location inside the lipid bilayer. An increment in the fluorescence quantum yield was observed, while the PS singlet oxygen generations remained high. Dialysis studies demonstrated that PS were released based on their hydrophobicity. Permeation analysis showed that all PS can reach the deeper regions of the skin. The Decyl Ester derivative/nanoparticle exhibited high photoactivity against Caco-2 cancer cells (in vitro studies). The PEG coated from F127/DPPC mixed vesicles are very promising nanocarriers for erythrosine and its derivatives.

Preparation and characterization of bioadhesive system containing hypericin for local photodynamic therapy.

Hypericin (Hyp) is a natural photoactive pigment utilized in the treatment of different types of cancer and antimicrobial inactivation using photodynamic therapy (PDT). Hyp is poorly soluble in water leading to problems of administration, getting close contact with the site, and bio-availability. Therefore, this study aimed to develop bioadhesive thermoresponsive system containing Hyp for local PDT. Carbomer 934P, poloxamer 407, and Hyp were used to prepare the thermoresponsive bioadhesive formulations. They were characterized for sol-gel transition temperature, mechanical, mucoadhesive, rheological (continuous flow and oscillatory) and dielectric properties, syringeability, in vitro Hyp release kinetics, ex vivo permeability, and photodynamic activity. The formulations displayed suitable gelation temperature and rheological characteristics. The compressional, mechanical and mucoadhesive properties, as well the syringeability showed the easiness of administration and the permanence of the system adhered to the mucosa or skin. The dielectric analysis helped to understand the Hyp availability, and its release presented an anomalous behavior. The system did not permeate the pig skin nor rat intestine and showed good biological photodynamic activity. Therefore, data obtained from the bioadhesive system indicate a potentially useful role as a platform for local hypericin delivery in PDT, suggesting it is worthy of in vivo evaluation.