Engineering of Silicone-based Mixtures for the Digital Light Processing of Åkermanite Scaffolds

Abstract Silicones mixed with oxide fillers are interesting precursors for several bioactive glass-ceramics. A key point is represented by the coupling of synthesis and shaping, since highly porous bodies, in form of foams or scaffolds, are first manufactured with silicones in the polymeric state, at low temperature, and later subjected to ceramic transformation. After successful application of direct ink writing, the present study illustrates the tuning of silicone-based mixtures in order to form akermanite (Ca2MgSi2O7) reticulated scaffolds by digital light processing. This implied the selection of commercial silicones, producing stable and homogeneous blends with a photocurable resin and enabling the manufacturing of defect-free printed scaffolds, before and after firing, without fillers. The blends were further refined with the introduction of fillers, followed by firing at 1100 °C, in air. Optimized samples (from H44 resin) and reactive fillers (including up to 4.5 wt.% borax additive), led to crack-free and phase-pure scaffolds with microporous struts

Glass powders and reactive silicone binder: Application to digital light processing of bioactive glass-ceramic scaffolds

Powdered \u2018silica-defective glasses\u2019, mixed with silicones, have been already shown as a promising solution for the sintering, in air, of glass-ceramics with complex geometries. A fundamental advantage of the approach is the fact silicones act as binders up to the firing temperature, at which they transform into silica. A specified \u2018target\u2019 glass-ceramic formulation is achieved through the interaction between glass powders and the binder-derived silica. The present paper is dedicated to the extension of the approach to the digital light processing of reticulated glass-ceramic scaffolds, for tissue engineering applications, starting from glass powders suspended in an engineered photocurable silicone-based binder. The silicone component, besides providing an extended binding action up to the maximum firing temperature, stabilizes the 3D-printed shapes during sintering. The formation of a rigid silica skeleton, from the transformation of the silicone binder, prevents from excessive viscous flow of softened glass. The final phase assemblage does not depend simply on glass devitrification but also on the glass/silica skeleton interaction

Glass powders and reactive silicone binder: Interactions and application to additive manufacturing of bioactive glass-ceramic scaffolds

A novel concept for the additive manufacturing of three-dimensional glass-ceramic scaffolds, to be used for tissue engineering applications, was based on fine glass powders mixed with a reactive binder, in the form of a commercial silicone. The powders consisted of ‘silica-defective glass’ specifically designed to react, upon firing in air, with the amorphous silica yielded by the binder. By silica incorporation, the glass was intended to reach the composition of an already known CaO[sbnd]Na 2 O[sbnd]B 2 O 3 [sbnd]SiO 2 system. Silica from the binder provided up to 15 wt% of the total silica. With the same overall formulation, silicone-glass powder mixtures led to nearly the same phase assemblage formed by the reference system, crystallizing into wollastonite (CaSiO 3 ) and Ca-borate (CaB 2 O 4 ). Samples from silicone-glass powder mixtures exhibited an excellent shape retention after firing, which was later exploited in highly porous reticulated scaffolds, obtained by means of direct ink writing (DIW).Fil: Elsayed, Hamada. Università di Padova; Italia. National Research Centre; EgiptoFil: Picicco, Martiniano. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; ArgentinaFil: Dasan, Arish. Alexander Dubček University of Trenčín; EslovaquiaFil: Kraxner, Jozef. Alexander Dubček University of Trenčín; EslovaquiaFil: Galusek, Dušan. Alexander Dubček University of Trenčín; EslovaquiaFil: Bernardo, Enrico. Università di Padova; Itali

3D Printing of Hierarchically Porous Lattice Structures Based on Åkermanite Glass Microspheres and Reactive Silicone Binder

The present study illustrates the manufacturing method of hierarchically porous 3D scaffolds based on åkermanite as a promising bioceramic for stereolithography. The macroporosity was designed by implementing 3D models corresponding to different lattice structures (cubic, diamond, Kelvin, and Kagome). To obtain micro-scale porosity, flame synthesized glass microbeads with 10 wt% of silicone resins were utilized to fabricate green scaffolds, later converted into targeted bioceramic phase by firing at 1100 °C in air. No chemical reaction between the glass microspheres, crystallizing into åkermanite, and silica deriving from silicone oxidation was observed upon heat treatment. Silica acted as a binder between the adjacent microspheres, enhancing the creation of microporosity, as documented by XRD, and SEM coupled with EDX analysis. The formation of ‘spongy’ struts was confirmed by infiltration with Rhodamine B solution. The compressive strength of the sintered porous scaffolds was up to 0.7 MPa with the porosity of 68–84%

Hierarchically porous 3D-printed akermanite scaffolds from silicones and engineered fillers

The present investigation is dedicated to the manufacturing of reticulated three-dimensional akermanite scaffolds, developed by direct reaction between silica, from the oxidation of a commercial silicone resin and oxide fillers, forming pastes for direct ink writing. Crack-free scaffolds, with dense and regular struts, were due to the use of CaCO3 (micro) and MgO nano-particles as reactive fillers. An excellent phase purity was obtained, with the help of the liquid phase provided by anhydrous sodium borate (Na2B4O7), upon firing. The structure of the scaffolds, finally, was successfully modified by using Mg(OH)2 and hydrated sodium borate: besides macro-porosity from direct ink writing, the new scaffolds exhibited homogenous ‘spongy’ struts (owing to water vapor release in the heating step), with no crack. Both types of scaffolds (with dense or porous struts) exhibited remarkable strength-to-density ratios

Towards a surface functionalisation and grafting of a polycarbosilane onto zirconium carbide particles for the development of hybrid core-shell structures

International audienc

Glass powders and reactive silicone binder: Application to digital light processing of bioactive glass-ceramic scaffolds

Powdered ‘silica-defective glasses’, mixed with silicones, have been already shown as a promising solution for the sintering, in air, of glass-ceramics with complex geometries. A fundamental advantage of the approach is the fact silicones act as binders up to the firing temperature, at which they transform into silica. A specified ‘target’ glass-ceramic formulation is achieved through the interaction between glass powders and the binder-derived silica. The present paper is dedicated to the extension of the approach to the digital light processing of reticulated glass-ceramic scaffolds, for tissue engineering applications, starting from glass powders suspended in an engineered photocurable silicone-based binder. The silicone component, besides providing an extended binding action up to the maximum firing temperature, stabilizes the 3D-printed shapes during sintering. The formation of a rigid silica skeleton, from the transformation of the silicone binder, prevents from excessive viscous flow of softened glass. The final phase assemblage does not depend simply on glass devitrification but also on the glass/silica skeleton interaction

Engineering of silicone-based mixtures for the digital light processing of Åkermanite scaffolds

Silicones mixed with oxide fillers are interesting precursors for several bioactive glass-ceramics. A key point is represented by the coupling of synthesis and shaping, since highly porous bodies, in form of foams or scaffolds, are first manufactured with silicones in the polymeric state, at low temperature, and later subjected to ceramic transformation. After successful application of direct ink writing, the present study illustrates the tuning of silicone-based mixtures in order to form åkermanite (Ca2MgSi2O7) reticulated scaffolds by digital light processing. This implied the selection of commercial silicones, producing stable and homogeneous blends with a photocurable resin and enabling the manufacturing of defect-free printed scaffolds, before and after firing, without fillers. The blends were further refined with the introduction of fillers, followed by firing at 1100 °C, in air. Optimized samples (from H44 resin) and reactive fillers (including up to 4.5 wt.% borax additive), led to crack-free and phase-pure scaffolds with microporous struts

Recent Advancements in Materials and Coatings for Biomedical Implants

Metallic materials such as stainless steel (SS), titanium (Ti), magnesium (Mg) alloys, and cobalt-chromium (Co-Cr) alloys are widely used as biomaterials for implant applications. Metallic implants sometimes fail in surgeries due to inadequate biocompatibility, faster degradation rate (Mg-based alloys), inflammatory response, infections, inertness (SS, Ti, and Co-Cr alloys), lower corrosion resistance, elastic modulus mismatch, excessive wear, and shielding stress. Therefore, to address this problem, it is necessary to develop a method to improve the biofunctionalization of metallic implant surfaces by changing the materials’ surface and morphology without altering the mechanical properties of metallic implants. Among various methods, surface modification on metallic surfaces by applying coatings is an effective way to improve implant material performance. In this review, we discuss the recent developments in ceramics, polymers, and metallic materials used for implant applications. Their biocompatibility is also discussed. The recent trends in coatings for biomedical implants, applications, and their future directions were also discussed in detail

Investigation of Zn2TiO4 as fluorescence quenching probe for sensing of metal ions

In the present work, rutile-free Zn2TiO4 has been synthesized by the solid-state method using TiO2 as hydrated titania and ZnO of 1:2 molar ratio. The reaction mixture was calcined at different temperature ranges, 550 °C to 950 °C. The rutile-free, cubic spinel-type Zn2TiO4 powders were obtained at 950 °C and confirmed by Raman, FI-IR spectroscopy, and XRD results. SEM images showed that the particles are irregular micron-sized and highly aggregated. From the diffuse reflectance spectral studies, the optical bandgap of the calcined products was calculated and it was found to be in the range of 3.25 to 3.79 eV. An attempt was made to examine the metal ion sensing properties of the prepared Zn2TiO4, by monitoring their photoluminescence intensity via quenching effects upon adding various metal ions. The sensing abilities were also evaluated using the standard Stern–Volmer quenching model. The results showed that Zn2TiO4 possesses high sensitivity toward iron ions