ABSTRACT
Overexposure of microorganisms to conventional drugs has led to resistant species that require new treatment strategies. This study prepared and characterized a nanocarrier of miconazole (MCZ) based on iron oxide nanoparticles (IONPs) functionalized with chitosan (CS), and tested its antifungal activity against biofilms of Candida albicans and Candida glabrata. IONPs-CS-MCZ nanocarrier was prepared by loading MCZ on CS-covered IONPs and characterized by physicochemical methods. Minimum inhibitory concentration (MIC) of the nanocarrier was determined by the microdilution method. Biofilms were developed (48 h) in microtiter plates and treated with MCZ-carrying nanocarrier at 31.2 and 78 µg/mL, in both the presence and absence of an external magnetic field (EMF). Biofilms were evaluated by total biomass, metabolic activity, cultivable cells (CFU), extracellular matrix components, scanning electron microscopy and confocal microscopy. Data were analyzed by two-way ANOVA and Holm-Sidak test (p < 0.05). A nanocarrier with diameter lower than 50 nm was obtained, presenting MIC values lower than those found for MCZ, and showing synergism for C. albicans and indifference for C. glabrata (fractional inhibitory concentration indexes of <0.12 and <0.53, respectively). IONPs-CS-MCZ did not affect total biomass and extracellular matrix. IONPs-CS-MCZ containing 78 µg/mL MCZ showed a superior antibiofilm effect to MCZ in reducing CFU and metabolism for single biofilms of C. albicans and dual-species biofilms. The EMF did not improve the nanocarrier effects. Microscopy confirmed the antibiofilm effect of the nanocarrier. In conclusion, IONPs-CS-MCZ was more effective than MCZ mainly against C. albicans planktonic cells and number of CFU and metabolism of the biofilms.
ABSTRACT
The Fe3O4@Poly(1,4-butanediol)/polyurethane nanocomposite is a highly interphase-dependable material with unique characteristics. Firstly, the nanoparticle's organic shell allows simple fabrication of very well dispersed nanocomposites and the incorporation of extremely high amounts of nanoparticles (NP) into the polymer matrix. Secondly, both chemical and physical aspects of the nanoparticles determine the material's mechanical behavior. The chemical functionality of the organic layer - free hydroxyl groups at the end of the tethered chains - ensures the material's stiffening through covalent bonds with the matrix, while being at molten state provides high flexibility and deformability yet maintaining mechanical resistance. As a result, nanocomposites at the low concentration region show increased elastic modulus and tensile strength and slight increase in total strain, while highly concentrated nanocomposites show reduction of elastic modulus and tensile strength and roughly double the total strain. The combination of the chemical and physical functionalities ensures high compatibility between nanoparticles and matrix and allows the production of highly concentrated - above 90% in weight - nanocomposites as a cohesive and flexible material, instead of a brittle wafer. This bifunctionality effect is unprecedented and the results open a wide range of new possibilities in the tailoring of functional nanomaterials for all sorts of applications in materials science.
ABSTRACT
This study synthesized and characterized a chlorhexidine (CHX)-carrier nanosystem based on iron oxide magnetic nanoparticles (IONPs) and chitosan (CS), and evaluated its antimicrobial effect on mono- and dual-species biofilms of Candida albicans and Streptococcus mutans. CHX was directly solubilized in CS-coated IONPs and maintained under magnetic stirring for obtaining the IONPs-CS-CHX nanosystem. Antimicrobial susceptibility testing for planktonic cells was performed by determining the minimum inhibitory concentration (MIC) of the nanosystem and controls. The effects of the IONPs-CS-CHX nanosystem on the formation of mono- and dual-species biofilms, as well as on pre-formed biofilms were assessed by quantification of total biomass, metabolic activity and colony-forming units. Data were analyzed by the Kruskal-Wallis' test or one-way analysis of variance, followed by the Student-Newman-Keuls' or Holm-Sidak's tests (α = 0.05), respectively. Physico-chemical results confirmed the formation of a nanosystem with a size smaller than 40 nm. The IONPs-CS-CHX nanosystem and free CHX showed similar MIC values for both species analyzed. In general, biofilm quantification assays revealed that the CHX nanosystem at 78 µg/mL promoted similar or superior antibiofilm effects compared to its counterpart at 39 µg/mL and free CHX at 78 µg/mL. These findings highlight the potential of CS-coated IONPs as preventive or therapeutic agents carrying CHX to fight biofilm-associated oral diseases.
