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Calcium phosphate and silicate-modified gold surfaces have potential applications in orthopedic and dental reconstruction, especially when combined with bone cement or dental resins. The aim of this study was to evaluate the formation of a Si–Na–Ca–P glass system nanoshell on functionalized gold nanoparticles. Stable gold nanoparticle suspensions were prepared by controlled reduction of HAuCl₄ using the sodium citrate method to obtain a nanogold-mercaptopropyltrimethyloxysilane (MPTS)–silicate–tetraethylothosilicate (TEOS)-capped particle solution. The nanoshells were formed when directly reacted with a 10^-4 M calcium phosphate ion solution. The median nanoparticle diameter was observed to be 15 nm. The MPTS–silicate–TEOS–functionalized nanoshell more effectively formed a glass shell as compared with a nonsilicate nanoshell. The changes in the surface morphology and composition were observed by a scanning transmission electron microscope equipped with energy-dispersive X-ray spectroscopy. As seen using EDS, the nanoshell was in a glass phase with CaO-poor layers.

Porous bioactive ceramic materials can be very useful on the filling of bone defects, as scaffolds for tissue engineering, or as carrier systems for the delivery of drugs. The present work describe an innovative methodology for producing porous bioactive ceramic structures, starting from hydroxylapatite or bioactive glass-ceramic powders, that present an adequate micro and macroporosity combined with compressive mechanical properties matching those of cancellous bone. The described processing route is based on a microwave baking process using a powder containing corn starch, sodium pyrophosphate and sodium bicarbonate as blowing agent, and can be used to produce either hydroxylapatite based or glass-ceramic porous structures. By using this new methodology it was possible to produce both porous bioactive glass-ceramic and HA/TCP bi-phasic structures with adequate micro and macroporosity combined with mechanical properties that will eventually allow for their successful use in a range of biomedical applications.

This study evaluated the possibility of obtaining bioactive coatings on polyethylene/bioactive glass composites exhibiting a very good mechanical performance. High molecular weight polyethylene (HMWPE) was reinforced with 10 to 40% (wt.) of a bioactive glass (BGE1) and a glass-ceramic (BGE1C), in the SiO₂-3CaOP₂O₅-MgO system. The composites were compounded by twin-screw extrusion (TSE) and then injection moulded into dumb-bell tensile samples. The composites presenting adequate mechanical properties were then coated with a bioactive layer by two methodologies: (i) an adapted biomimetic route using a similar glass as a precursor of calcium-phosphate (Ca-P) film deposition, and (ii) the production of a ‘sandwich’ with bioactive glass particles, previously mixed with UHMWPE powders, made to adhere to both faces of tensile samples by compression moulding. The obtained results indicated that it is possible to produce composites presenting a modulus of 11.2 GPa coupled with a tensile strength of around 117 MPa. The developed composites could be coated with a Ca-P layer by an adapted biomimetic route. Furthemore, the ‘sandwich’ route allowed for the production of load-bearing composites, presenting a highly bioactive surface, which strongly adheres to the HMWPE matrix composites.

Elastic moduli, (n=3) for eight composite systems were determined using an ultrasonic method. Mean values for glass composite ranged from 14.81 ± 0.14 GPa for silane treated filler to 10.84 ± 0.35 GPa for non-silane treated material. Mean value for Young’s modulus of low temperature fired inorganic silane treated filler was 11.96 ± 0.05 GPa. Using a Kokubo biomimetic method the eight composite substrates were also evaluated to determine their ability to deposit calcium, phosphorus and sodium on their surface when stored in a dynamic 1.0 concentration of SBF solution for 30 days @ 37°C. Single glass and low temperature fired inorganic constituent of same composition (SiO₂-CaO-Na₂O-P₂O₅) were used, combined in two different dimethacrylate resin matrix polymers. Fillers were introduced with and without silane treatment. Deposits of Ca and P were observed for composite systems. Strong correlation was found between deposition of Ca and P for each substrate (p<0.001). Data indicate that significant proportions of deposition came from SBF solution. Elastic moduli showed a significant effect for the use of silane treatment, as well as between glass and the same low-temperature fired inorganic formulation (p=0.05).

Experimental composites containing bioactive glass, glass-ceramic and bioactive low temperature fired inorganic fillers (SiO₂-CaO-P₂O₅-Na₂O) were synthesized by wet chemistry. Two chemically activated dimethacrylate matrix resins were used together with 0 or 30% low molecular weight hydrophilic monomer. Composites contained 70 or 65 (wt%) filler particles with and without silane treatment. Fracture toughness (K_Ic) (n=5) was performed on specimens following storage in either SBF or distilled water @ 37°C for 30 days. Fracture toughness discriminated between glass-ceramic, glass and low temperature inorganic filler (P< 0.001). Mean values for silane treated glass-ceramic ranged from 1.56 ± 0.41 MPa.m^0.5 to 0.4 ± 0.18 MPa.m^0.5 for the none silane treated composite. In contrast values for the glass filler were from 1.39 ± 0.27 MPa.m^0.5 for the silane treated to 0.42 ± 0.03 MPa.m^0.5 for the non-silane treated. Mean fracture toughness values for low temperature fired inorganic constituent ranged from 1.03 ± 0.19 MPa.m^0.5 for silane treated and 0.36 ± 0.28 MPa.m^0.5 for non-silane treated. No effect due to storage in SBF or distilled water was found.