Mesoporous silica SBA-16/hydroxyapatite-based composite for ciprofloxacin delivery to bacterial bone infection

The development of systems that can prevent infections and also ensure bone integration as well as regeneration have been of great interest for pharmaceutical technology. In this study, we show the synthesis of surface-functionalized mesoporous silica (SBA-16) and silica composed of calcium phosphate (SBA-16/HA) particles in order to be applied as efficient drug delivery carriers. The particles were synthesized, functionalized with 3-aminopropyltriethoxysilane (APTES) by post-synthesis grafting and loaded with the osteomyelitis antibiotic agent ciprofloxacin. Moreover, the diethylenetriaminepentacetic acid (DTPA) was anchored in silica-APTES to allow measurements of biological process at molecular and cellular levels. Particles were physicochemically characterized by small angle X-ray scattering (SAXS), elemental analysis (CHN), thermogravimetric analysis (TGA), N₂ adsorption and zeta potential analysis. Functionalized silica particles were radiolabeled with technetium-99m showing high radiochemical yields and high radiolabeled stability. In vivo experiments results showed higher bone uptake of the SBA-16/HAAPTES than SBA-16APTES. In addition, bactericidal efficacy of these particles was tested against microorganisms present in bone infection, and our composites had bactericidal efficiency comparable to free-ciprofloxacin. In summary, taking into account the great potential of these silica mesoporous and nanocomposite structures to carry molecules, besides their bactericidal efficacy, these materials are promising candidates for bone infection treatment.