RESUMO
In this work, we synthesized a new composite material comprised of previously formulated resveratrol nanobelt-like particles (ResNPs) and selenium nanoparticles (SeNPs), namely ResSeNPs. Characterization was provided by FESEM and optical microscopy, as well as by UV-Vis and FTIR spectroscopy, the last showing hydrogen bonds between ResNPs and SeNPs. DPPH, TBA, and FRAP assays showed excellent antioxidative abilities with ResNPs and SeNPs contributing mainly to lipid peroxidation inhibition and reducing/scavenging activity, respectively. The antibacterial effect against common medicinal implant colonizers pointed to notably higher activity against Staphylococcus isolates (minimal inhibitory concentrations 0.75-1.5%) compared to tested gram-negative species (Escherichia coli and Pseudomonas aeruginosa). Antibiofilm activity against S. aureus, S. epidermidis, and P. aeruginosa determined in a crystal violet assay was promising (up to 69%), but monitoring of selected biofilm-related gene expression (pelA and algD) indicated the necessity of the involvement of a larger number of genes in the analysis in order to further establish the underlying mechanism. Although biocompatibility screening showed some cytotoxicity and genotoxicity in MTT and alkaline comet assays, respectively, it is important to note that active antioxidative and antibacterial/antibiofilm concentrations were non-cytotoxic and non-genotoxic in normal MRC-5 cells. These results encourage further composite improvements and investigation in order to adapt it for specific biomedical purposes.
RESUMO
OBJECTIVE: The objective was to determine the antibiofilm efficacy of Cymbopogon martinii and Thymus zygis essential oils and to estimate the disruption potential of oil-based endodontic irrigants on the multispecies biofilm formed in the root canals of extracted teeth. DESIGN: The essential oils were characterized (GC-MS), while their antibacterial and cytotoxic properties were detected by microdilution and MTT assays. Particles sizes and polydispersity indices were determined for the irrigants. The isolates from root canals of pediatric patients were identified (MALDI-TOF). The multispecies biofilms were formed from Streptococcus mitis, Streptococcus sanguinis and Enterococcus faecalis. Antibiofilm properties of the essential oils and irrigants were determined by crystal violet and plate counting assay. Statistical analysis was performed by one-way ANOVA. RESULTS: The screening of biofilm biomass revealed a disruption potential of C. martinii essential oil. The plate counting assay showed the efficacy of both oils in diminishing cell viability: high in biofilms (reduction of log10CFU was 2.75-2.87) and moderate in the planktons formed above. The essential oil-based irrigants showed the same antibiofilm activity as in the control (1.5 % sodium hypochlorite) for C. martini and almost 2-fold higher for T. zygis. Successive irrigations with 1.5 % sodium hypochlorite, saline and an oil-based irrigant was more efficient for C. martini than for the control (reductions of log10CFU was 1.69 and 1.14, respectively). CONCLUSIONS: Notable activities achieved by essential oils and oil-based irrigants, particularly regarding C. martini, against the biofilm consisting of S. mitis, S. sanguinis, and E. faecalis, are expected to encourage further research in endodontics.