Rafael Soares Stenico

S. aureus plays a central role in chronic rhinosinusitis (CRS), contributing to acute exacerbations and persistent infections through biofilm formation. With rising antibiotic resistance, bioactive glasses such as F18 and 45S5 have emerged as potential alternative antimicrobial agents. To evaluate the antimicrobial effects of F18 and 45S5 on S. aureus isolates from CRS patients, focusing on planktonic growth, biofilm formation, and mechanisms of action. Clinical S. aureus isolates were exposed to F18 and 45S5 (0–512 μg/mL) using a modified Calgary Biofilm Device. Biofilm biomass was quantified by crystal violet staining and spectrophotometry. A pH‐controlled assay was performed to determine whether alkalinization mediated antibiofilm effects. Inductively coupled plasma analysis characterized F18 ion‐release kinetics. Expression of biofilm‐related genes (icaA, icaB, icaD, agrA, agrC) was quantified, and biofilm morphology was examined by scanning electron microscopy. Both bioglasses inhibited biofilm formation at concentrations ≥ 128 μg/mL but did not eradicate mature biofilms. At 512 μg/mL, F18 and 45S5 reduced the biofilm optical density by 78% and 67%, respectively. Although pH elevation occurred, biofilm inhibition was independent of pH variation. F18 exposure downregulated ica operon genes but not agr genes. Ion analysis demonstrated concentration‐dependent release of Ca and Si, with no evidence of apatite formation. SEM showed reduced extracellular matrix and altered bacterial organization. F18 and 45S5 inhibit S. aureus biofilm formation through pH‐independent mechanisms associated with ion release and suppression of matrix‐related genes, supporting their potential as adjunctive strategies in CRS management.

Bacterial contamination and low osteogenic activity are the major causes of dental implant failure. The development of titanium coatings has provided new research directions to improve both antibacterial and osteogenic activity. In this study, we constructed phospholipidic films containing carbonate hydroxyapatite added or not to silver nanoparticles. The purpose was to reduce the biofilm formation while maintaining the osteogenic potential of surfaces. Phospholipid monolayers were transferred to titanium by Langmuir–Blodgett (LB) technique and resulted in dense, ordered and uniform films. Modified surfaces were evaluated by X-ray photoelectron spectroscopy, energy-dispersive spectroscopy, Fourier-transform infrared spectroscopy, and atomic force microscopy to confirm that films were successfully coated onto the titanium substrate. In addition, surface free energy and roughness analyses indicated that surfaces were smooth and hydrophilic. ICP-OES analysis confirmed the absence of silver nanoparticle lixiviation from the coatings. Furthermore, the coatings had great biocompatibility and promoted the proliferation of osteoblast-like cells. Microbiological findings showed that biofilm formation and bacterial adhesion were significantly reduced for the experimental coatings; species closely related to peri-implant diseases and associated with increased biofilm volume were shown reduced. Addition of silver nanoparticles did not improve biofilm control. In conclusion, the phospholipidic films proposed to modify the titanium surfaces are beneficial for osseointegration and can act as a promising method to reduce the biofilm formation and bacterial colonization for dental implants.

The cloud point extraction method enables the selective separation of hematite nanoparticles from ionic iron in aqueous dispersions, providing a low-cost and environmentally friendly alternative for analytical applications.