Sol-gel synthesis of spherical monodispersed bioactive glass nanoparticles co-doped with boron and copper

In this work, an optimized sol-gel process for the synthesis of spherical and monodispersed bioactive glass nanoparticles doped with boron and copper was developed, by investigating different synthesis parameters. The obtained glasses were characterized in terms of morphology, composition, dispersibility, structure and in vitro reactivity. The performed characterizations demonstrated that shape, dimension and dispersion can be tailored by acting on the timing of the addition of the catalyst and on the synthesis process, in particular the centrifugation step. The optimized glass particles showed a spherical shape, good ions incorporation and good dispersion. In vitro bioactivity test demonstrated that the boron and copper addition did not interfere with the glass ability to induce the precipitation of hydroxyapatite. The shape, dispersion, bioactive behavior and content of boron and copper of these novel bioactive glass particles make them very promising for both hard and soft tissue engineering applications

Poly(ε-caprolactone)/bioactive glass composite electrospun fibers for tissue engineering applications

In this work, composite electrospun fibers containing innovative bioactive glass nanoparticles were produced and characterized. Poly(ε-caprolactone), benign solvents, and sol–gel B- and Cu-doped bioactive glass powders were used to fabricate fibrous scaffolds. The retention of bioactive glass nanoparticles in the polymer matrix, the electrospinnability of this novel solution and the obtained electrospun composites were extensively characterized. As a result, composite electrospun fibers characterized by biocompatibility, bioactivity, and exhibiting overall properties adequate for both hard and soft tissue engineering applications, have been produced. The addition of these bioactive glass nanoparticles was, indeed, able to impart bioactive properties to the fibers. Cell culture studies show promising results, demonstrating proliferation and growth of cells on the composite fibers. Wettability, degradation rate, and mechanical performance were also tested and are in line with previous results

UV-Cured Bio-Based Acrylated Soybean Oil Scaffold Reinforced with Bioactive Glasses

In this study, a bio-based acrylate resin derived from soybean oil was used in combination with a reactive diluent, isobornyl acrylate, to synthetize a composite scaffold reinforced with bioactive glass particles. The formulation contained acrylated epoxidized soybean oil (AESO), isobornyl acrylate (IBOA), a photo-initiator (Irgacure 819) and a bioactive glass particle. The resin showed high reactivity towards radical photopolymerisation, and the presence of the bioactive glass did not significantly affect the photocuring process. The 3D-printed samples showed different properties from the mould-polymerised samples. The glass transition temperature Tg showed an increase of 3D samples with increasing bioactive glass content, attributed to the layer-by-layer curing process that resulted in improved interaction between the bioactive glass and the polymer matrix. Scanning electron microscope analysis revealed an optimal distribution on bioactive glass within the samples. Compression tests indicated that the 3D-printed sample exhibited higher modulus compared to mould-synthetized samples, proving the enhanced mechanical behaviour of 3D-printed scaffolds. The cytocompatibility and biocompatibility of the samples were evaluated using human bone marrow mesenchymal stem cells (bMSCs). The metabolic activity and attachment of cells on the samples' surfaces were analysed, and the results demonstrated higher metabolic activity and increased cell attachment on the surfaces containing higher bioactive glass content. The viability of the cells was further confirmed through live/dead staining and reseeding experiments. Overall, this study presents a novel approach for fabricating bioactive glass reinforced scaffolds using 3D printing technology, offering potential applications in tissue engineering

Human T-Cell Responses to Metallic Ion-Doped Bioactive Glasses

Biomaterials are extensively used as replacements for damaged tissue with bioactive glasses standing out as bone substitutes for their intrinsic osteogenic properties. However, biomaterial implantation has the following risks: the development of implant-associated infections and adverse immune responses. Thus, incorporating metallic ions with known antimicrobial properties can prevent infection, but should also modulate the immune response. Therefore, we selected silver, copper and tellurium as doping for bioactive glasses and evaluated the immunophenotype and cytokine profile of human T-cells cultured on top of these discs. Results showed that silver significantly decreased cell viability, copper increased the T helper (Th)-1 cell percentage while decreasing that of Th17, while tellurium did not affect either cell viability or immune response, as evaluated via multiparametric flow cytometry. Multiplex cytokines assay showed that IL-5 levels were decreased in the copper-doped discs, compared with its undoped control, while IL-10 tended to be lower in the doped glass, compared with the control (plastic) while undoped condition showed lower expression of IL-13 and increased MCP-1 and MIP-1β secretion. Overall, we hypothesized that the Th1/Th17 shift, and specific cytokine expression indicated that T-cells might cross-activate other cell types, potentially macrophages and eosinophils, in response to the scaffolds

Antibacterial inorganic coatings on metallic surfaces for temporary fixation devices

Bacterial contamination and bone tissue overgrowth are currently the main issues for temporary fixation devices. The aim of this research is the development of innovative inorganic coatings able to reduce bacterial adhesion and bone tissue overgrowth without hampering cytocompatibility. 316L stainless-steel, Titanium grade4 and Titanium grade5 were selected as substrates, as currently used in temporary fixation devices. Starting from previous results on silica, alumina and zirconia were selected as coating matrices, according to their higher chemical stability, reduced bacterial adhesion and possible reduction of tissue overgrowth. Coatings were produced by co-sputtering. Coating adhesion was evaluated by tape test. Samples were immersed in ultrapure water up to 28 days to investigate silver release and chemical stability in fluids. Surface roughness was measured by contact profilometry. Surface wettability was determined by contact angle measurements and antibacterial activity was studied against antibiotic resistant S aureus. The research demonstrates the possibility to obtain coatings with roughness lower than the critical threshold for the increase of bacterial adhesion (0.2 mu m) and optimal mechanical adhesion to metallic substrates. Coating chemical stability in water is strongly affected by the coating matrix composition. Silver release can be tailored to obtain antibacterial and biocompatible surfaces

Surface modification of silicate, borosilicate, and phosphate bioactive glasses to improve/control protein adsorption: PART II

Bioactive glasses (BGs) are characterized by high biocompatibility and bioactivity and are particularly promising for bone tissue regeneration. Once implanted, the BGs interact with the environment and adsorb chemical moieties and biomolecules. Proteins in body fluids are critical for the success of implants, because the adsorption of specific proteins can either promote or inhibit the adhesion of surrounding tissue or other factors such as bacteria. Controlling protein adsorption by tailoring the surface properties of implanted biomaterials is fundamental. This can determine the fate of the implant. In the current study, four BG compositions (two silicates, one borosilicate, and one phosphate glass) and three model proteins (fibronectin, chimeric avidin, and streptavidin) were considered. Each BG was surface pretreated, and the adsorption of fluorescently labeled fibronectin, chimeric avidin, or streptavidin was monitored. Untreated surfaces were used as controls. The amount and spatial distribution of each protein were estimated by confocal microscopy in fluorescence modality, followed by protein clustering analysis. Although streptavidin was not adsorbed efficiently on any of the considered substrates, BGs were successfully coated with fibronectin and chimeric avidin. Both proteins showed different affinities and surface distributions as functions of the implemented pretreatment on each substrate