RESUMEN
HYPOTHESIS: The treatment of bone fractures still represents a challenging clinical issue when complications due to impaired bone remodelling (i.e. osteoporosis) or infections occur. These clinical needs still require a radical improvement of the existing therapeutic approach through the design of advanced biomaterials combining the ability to promote bone regeneration with anti-adhesive properties able to minimise unspecific biomolecules adsorption and bacterial adhesion. Strontium-containing mesoporous bioactive glasses (Sr-MBG), which are able to exert a pro-osteogenic effect by releasing Sr2+ ions, have been successfully functionalised to provide mixed-charge (NH3â/COOâ) surface groups with anti-adhesive abilities. EXPERIMENTS: Sr-MBG have been post-synthesis modified by co-grafting hydrolysable short chain silanes containing amino (aminopropylsilanetriol) and carboxylate (carboxyethylsilanetriol) moieties to achieve a zwitterionic zero-charge surface. The final system was then characterised in terms of textural-structural properties, bioactivity, cytotoxicity, pro-osteogenic and anti-adhesive capabilities. FINDINGS: After zwitterionization the in vitro bioactivity was maintained, as well as the ability to release Sr2+ ions which are capable of inducing a mineralization process. Irrespective of their size, Sr-MBG particles did not exhibit any cytotoxicity in pre-osteoblastic MC3T3-E1 up to the concentration of 75 µg/mL. Finally, the zwitterionic Sr-MBGs showed a significant reduction of serum protein adhesion with respect to the pristine ones. These results open promising future expectations in the design of nanosystems which combine pro-osteogenic and anti-adhesive properties.
Asunto(s)
Materiales Biocompatibles/metabolismo , Regeneración Ósea , Huesos/metabolismo , Estroncio/metabolismo , Animales , Materiales Biocompatibles/química , Huesos/química , Vidrio/química , Humanos , Tamaño de la Partícula , Porosidad , Estroncio/química , Propiedades de SuperficieRESUMEN
We present a novel protocol that uses single-cell force spectroscopy to characterize the bacteria-to-surface interactions involved in early steps of biofilm formation. Bacteria are immobilized as a monolayer by electrostatic interactions on a polyethylenimine-coated silica bead, and the Escherichia coli-bead complex is then glued on a tipless cantilever. We validated our new protocol by comparing to earlier published methods using single bacteria, but in contrast to these, which carry out bacterial attachment to the bead after fixation to the cantilever, our protocol results in more reliable production of usable cell probes. Measurements of interactions of E. coli with bio-inspired surfaces by single-cell force spectroscopy yielded comparable detachment forces to those found with the previous methods.