Zinc-Doped Bioactive Glass/Polycaprolactone Hybrid Scaffolds Manufactured by Direct and Indirect 3D Printing Methods for Bone Regeneration.

A novel organic-inorganic hybrid, based on SiO-CaO-ZnO bioactive glass (BG) and polycaprolactone (PCL), associating the highly bioactive and versatile bioactive glass with clinically established PCL was examined. The BG-PCL hybrid is obtained by acid-catalyzed silica sol-gel process inside PCL solution either by direct or indirect printing. Apatite-formation tests in simulated body fluid (SBF) confirm the ion release along with the hybrid's bone-like apatite forming.

Bioactive glass-based organic/inorganic hybrids: an analysis of the current trends in polymer design and selection.

Bioactive glass-based organic/inorganic hybrids are a family of materials holding great promise in the biomedical field. Developed from bioactive glasses following recent advances in sol-gel and polymer chemistry, they can overcome many limitations of traditional composites typically used in bone repair and orthopedics. Thanks to their unique molecular structure, hybrids are often characterized by synergistic properties that go beyond a mere combination of their two components; it is possible to synthesize materials with a wide variety of mechanical and biological properties.

Osteogenic Effect of Fisetin Doping in Bioactive Glass/Poly(caprolactone) Hybrid Scaffolds.

Treating large bone defects or fragile patients may require enhancing the bone regeneration rate to overcome a weak contribution from the body. This work investigates the osteogenic potential of nutrient fisetin, a flavonoid found in fruits and vegetables, as a doping agent inside the structure of a SiO-CaO bioactive glass-poly(caprolactone) (BG-PCL) hybrid scaffold. Embedded in the full mass of the BG-PCL hybrid during one-pot synthesis, we demonstrate fisetin to be delivered sustainably; the release follows a first-order kinetics with active fisetin concentration being delivered for more than 1 month (36 days).

Tailored therapeutic release from polycaprolactone-silica hybrids for the treatment of osteomyelitis: antibiotic rifampicin and osteogenic silicates.

The treatment of osteomyelitis, a destructive inflammatory process caused by bacterial infections to bone tissue, is one of the most critical challenges of orthopedics and bone regenerative medicine. The standard treatment consists of intense antibiotic therapies combined with tissue surgical debridement and the application of a bone defect filler material. Unfortunately, commercially available candidates, such as gentamicin-impregnated polymethylmethacrylate cements, possess very poor pharmacokinetics (, 24 hours burst release) and little to no regenerative potential.

Mechanism of Calcium Incorporation Inside Sol-Gel Silicate Bioactive Glass and the Advantage of Using Ca(OH) over Other Calcium Sources.

Calcium is an essential component of osteogenesis and is often required for imparting significant bioactivity to synthetic bone substitutes and, in particular, silicate-based materials. However, the mechanism of calcium incorporation inside sol-gel silicates is poorly understood. In this work, we shed light on the determinant parameters for incorporation of calcium into acid-base-catalyzed sol-gel silicates at ambient temperature: increasing the pH above the isoelectric point of silicic acid and the nature of the calcium counterion in the calcium precursor are found to be the key.

Bioactive Glass/Polycaprolactone Hybrid with a Dual Cortical/Trabecular Structure for Bone Regeneration.

Organic-inorganic hybrid biomaterials stand as a promise for combining bone bonding and bone mineral-forming ability, stimulation of osteogenic cells, and adequate mechanical properties. Bioactive glass (BG)-polycaprolactone (PCL) hybrids are of special interest as they gather the ability of BG to enhance osteoblast-mediated bone formation with the slow degradation rate and the toughness of PCL. In this study, BG-PCL hybrids were synthesized in the form of scaffold, owing to a dual cortical/trabecular structure mimicking the bone architecture.

Optimized Bioactive Glass: the Quest for the Bony Graft.

Technological advances have provided surgeons with a wide range of biomaterials. Yet improvements are still to be made, especially for large bone defect treatment. Biomaterial scaffolds represent a promising alternative to autologous bone grafts but in spite of the numerous studies carried out on this subject, no biomaterial scaffold is yet completely satisfying.

Strontium-Substituted Bioceramics Particles: A New Way to Modulate MCP-1 and Gro-α Production by Human Primary Osteoblastic Cells.

Background: To avoid morbidity and limited availability associated with autografts, synthetic calcium phosphate (CaP) ceramics were extensively developed and used as bone filling materials. Controlling their induced-inflammatory response nevertheless remained a major concern. Strontium-containing CaP ceramics were recently demonstrated for impacting cytokines' secretion pattern of human primary monocytes.

Physicochemical regulation of TGF and VEGF delivery from mesoporous calcium phosphate bone substitutes.

Aim: Determination of the physicochemical parameters governing growth factors (GFs) adsorption and release from mesoporous calcium phosphate ceramics.

Materials & Methods: Six mesoporous calcium phosphate ceramics prepared by soft and hard templating were loaded with two different physiological concentrations of TGF-β1 or VEGF and their in vitro kinetics of adsorption/release were studied.

Results: This low GF loading promotes adsorption on the highest binding sites.

Bioactive glass-gelatin hybrids: building scaffolds with enhanced calcium incorporation and controlled porosity for bone regeneration.

Thanks to their active promotion of bone formation, bioactive glasses (BG) offer unique properties for bone regeneration, but their brittleness prevents them from being used in a wide range of applications. Combining BG with polymers into a true hybrid system is therefore an ideal solution to associate toughness from the polymer and stimulation of bone mineralization from the glass. In this work, we report the synthesis and characterization of hybrid scaffolds based on SiO-CaO bioactive glass and gelatin, a hydrolyzed form of bone type-I collagen.

In vitro and in vivo evaluation of the inflammatory potential of various nanoporous hydroxyapatite biomaterials.

Aim: To discriminate the most important physicochemical parameters for bone reconstruction, the inflammatory potential of seven nanoporous hydroxyapatite powders synthesized by hard or soft templating was evaluated both in vitro and in vivo.

Materials & Methods: After physical and chemical characterization of the powders, we studied the production of inflammatory mediators by human primary monocytes after 4 and 24 h in contact with powders, and the host response after 2 weeks implantation in a mouse critical size defect model.

Results: In vitro results highlighted increases in the secretion of TNF-α, IL-1, -8, -10 and proMMP-2 and -9 and decreases in the secretion of IL-6 only for powders prepared by hard templating.

Bioactive glass hybrids: a simple route towards the gelatin-SiO₂-CaO system.

Bioactive glass hybrids are among the most promising materials for bone regeneration, but the incorporation of calcium, a key element for mineralization properties of the implant, into the inorganic part of the hybrid network is challenging. We present here a synthesis route towards both class I and II gelatin-bioactive glass hybrids allowing the efficient incorporation of calcium ions at low temperature.

Cobalt-releasing 1393 bioactive glass-derived scaffolds for bone tissue engineering applications.

Loading biomaterials with angiogenic therapeutics has emerged as a promising approach for developing superior biomaterials for engineering bone constructs. In this context, cobalt-releasing materials are of interest as Co is a known angiogenic agent. In this study, we report on cobalt-releasing three-dimensional (3D) scaffolds based on a silicate bioactive glass.

In vitro reactivity of Cu doped 45S5 Bioglass® derived scaffolds for bone tissue engineering.

Cu-doped 45S5 bioactive glasses with varying Cu contents were fabricated and used to process 3D porous scaffolds via the foam replica technique. Cu-doping results in the weakening of the glass network and a decrease in its glass transition temperature. Acellular in vitro studies revealed very high bioactivity independent of Cu doping as indicated by the fast formation of a carbonated hydroxyapatite layer (CHA) on scaffold surfaces after immersion in simulated body fluid (SBF).

Green and safe in situ templating of bioactive glass scaffolds for bone tissue engineering.

This communication reports a new process for the synthesis of bioactive glass foams. This process is based on the use of gelatin as a template during the foaming of a sol, and the gelled gelatin template formed in situ maintains the foam structure during further condensation of the glass network.

Influence of glass scaffolds macroporosity on the bioactive process.

Little is known about the ideal morphology for three-dimensional (3D) porous scaffolds to be used in bone tissue engineering. The present study will supply useful data about the dependence of the mineralization process upon macroporous features of bioactive glass scaffolds. It also points out the difficulty in distinguishing between the bioactive properties of scaffolds if using common characterization techniques often considered as standard techniques to assess in vitro bioactivity.

87Sr solid-state NMR as a structurally sensitive tool for the investigation of materials: antiosteoporotic pharmaceuticals and bioactive glasses.

Strontium is an element of fundamental importance in biomedical science. Indeed, it has been demonstrated that Sr(2+) ions can promote bone growth and inhibit bone resorption. Thus, the oral administration of Sr-containing medications has been used clinically to prevent osteoporosis, and Sr-containing biomaterials have been developed for implant and tissue engineering applications.

A new insight into the dissociating effect of strontium on bone resorption and formation.

Calcium phosphates are widely used as biomaterials and strontium (Sr) is known to have the ability to modify the bone balance towards osteosynthesis. In the present study we investigated the capacity of Sr-substituted sol-gel calcium phosphate to modify the expression of genes and proteins involved in extracellular matrix synthesis by primary bone cells. We first determined the most effective concentration of strontium using human primary bone cells.

The effect of zinc on hydroxyapatite-mediated activation of human polymorphonuclear neutrophils and bone implant-associated acute inflammation.

Hydroxyapatite (HA) is widely used as coating biomaterial for prosthesis metal parts and as bone substitute. The release of HA particles induces an inflammatory response and, if uncontrolled, could result in implant loss. At the inflamed site, the polymorphonuclear cells (PMNs) represent the earliest phagocytic cells that predominate the cellular infiltrate.

Polymorphonuclear neutrophil response to hydroxyapatite particles, implication in acute inflammatory reaction.

Hydroxyapatite (HA) is widely used as a bone substitute or coating biomaterial in bone diseases or prosthesis metal parts. The release of HA particles induces an inflammatory response and, if uncontrolled, could result in implant loss. Among the hallmarks of such inflammatory response is early recruitment of the polymorphonuclear cells (PMNs).

Influence of the zinc concentration of sol-gel derived zinc substituted hydroxyapatite on cytokine production by human monocytes in vitro.

A possible complication associated with the implantation of hydroxyapatite (HA)-based prosthesis is the release of particles. These particles can be phagocyted by monocytes that are among the first cells to colonize the inflammatory site. The activated monocytes produce inflammatory mediators such as cytokines that cause osteoclasts activation.

MMP-2, MMP-9 and their inhibitors TIMP-2 and TIMP-1 production by human monocytes in vitro in the presence of different forms of hydroxyapatite particles.

After calcium-phosphates biomaterials based implantation like hydroxyapatite (HA) coating, particles are released in the periprosthetic tissues. Wear-debris induced fibrous membranes contain macrophage subsets that can produce metalloproteinases (MMPs), which are considered to be key enzymes in extra-cellular matrix turnover. Tissue inhibitors of metalloproteinases (TIMPs) are important regulator of MMPs activity.

Effects of bioactive glass particles and their ionic products on intracellular concentrations.

Numerous studies have described the bioactive properties of glass particles in the SiO(2)-CaO-Na(2)O-P(2)O(5) system. This kind of material is capable of developing a direct contact with bone through dissolution and physicochemical reactions. We have investigated the influence of bioactive particles, and ionic products from the same particles, on the intracellular concentrations in monocyte cells, which are among the first cells to colonize implantation sites.

Importance of hydroxyapatite particles characteristics on cytokines production by human monocytes in vitro.

Calcium phosphate bioceramics have been applied as bone substitutes for several decades. Aseptic loosening after total joint arthroplasty is a major problem in orthopaedic surgery. Hydroxyapatite particles from materials wear have been reported as the main cause of implant failure.