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Large and critical bone defect reconstruction is still a hard challenge in tumor resections, non-unions, some traumatisms and articular prosthesis revisions. The application of electron beam melting technology (EBM) to implant manufacturing constitutes a promising alternative, which provides better biomechanics and customized solutions. Implant infections are one of the most serious complications associated with surgical treatments, which require immediate solutions for achieving better clinical results. Herein, to confer antimicrobial properties, a simple and cost-effective approach based on a bifunctionalization process to create a zwitterionic surface on Ti6Al4V EBM implants is proposed. The obtained results show a notable reduction of bacterial adhesion (more than 97%) and total inhibition of biofilm formation, combined with demonstrated biocompatibility and bioactivity, permitting cell adhesion on the entire surface of these 3D zwitterionic scaffolds. This surface zwitterionization provides new perspectives for custom-made Ti6Al4V EBM implants for bone tissue regeneration with antimicrobial properties.

The bioactivity behaviour of SBA-15, MCM-48, MCM-41 mesoporous materials, is revisited in this paper. The influence of their different textural and structural properties on apatite formation is outlined and strategies to modify their kinetics are proven and discussed. On the basis of the experimental data showing the feasibility of control of the bioactivity kinetics on mesoporous materials, together with their controlled drug release abilities, new possibilities for tissue engineering developments are proposed.

Mesoporous silica SBA-15 was prepared to evaluate its effectiveness as a matrix for the controlled delivery of macrolide-type antibiotics. Two types of material were used to evaluate the delivery: calcined samples and samples functionalized with octyltrimethoxysilane and octadecyltrimethoxysilane. The samples were charged with the macrolide antibiotic erythromycin and the release assays were carried out in vitro. It has been observed that the release rate decreases as the population of hydrophobic –CH2 moieties in the host increases.

The interaction of new nanocomposite mesoporous glass/hydroxyapatite (MGHA) scaffolds with immune cells involved in both innate and acquired immunity has been studied in vitro as an essential aspect of their biocompatibility assessment. Since the immune response can be affected by the degradation products of bioresorbable scaffolds and scaffold surface changes, both processes have been evaluated. No alterations in proliferation and viability of RAW-264.7 macrophage-like cells were detected after culture on MGHA scaffolds which did not induce cell apoptosis. However, a slight cell size decrease and an intracellular calcium content increase were observed after contact of this cell line with MGHA scaffolds or their extracts. Although no changes in the percentages of RAW cells with low and high contents of reactive oxygen species (ROS) are observed by the treatment with 7 day extracts, this study has revealed modifications of these percentages after direct contact with scaffolds and by the treatment with 24 h extracts, related to the high reactivity/bioactivity of this MGHA nanocomposite at initial times. Furthermore, when normal fresh murine spleen cells were used as an experimental model closer to physiological conditions, no significant alterations in the activation of different immune cell subpopulations were detected in the presence of 24 h MGHA extract. MGHA scaffolds did not affect either the spontaneous apoptosis or intracellular cytokine expression (IL-2, IL-10, IFN-gamma, and TNF-alpha.) after 24 h treatment. The results obtained in the present study with murine immune cell subpopulations (macrophages, lymphocytes B, lymphocytes T and natural killer cells) support the biocompatibility of the MGHA material and suggest an adequate host tissue response to their scaffolds upon their implantation.

This study reports the design and preparation of zwitterionic nanocrystalline hydroxyapatite (HA) capable of inhibiting bacterial adhesion while allowing osteoblast cell colonization. The surface functionalization of HA powders was carried out by post-synthesis grafting of 3-aminopropyltriethoxysilane (APTES) and carboxyethylsilanetriol sodium salt (CES) as amine and carboxylate precursors, respectively. The successful functionalization of HA surfaces was assessed by elemental chemical analysis, FTIR, 29Si, 31P and 13C solid state CP/MAS NMR and ζ-potential measurements, and the zwitterionic nature of the synthesized HA was proved through the presence of –NH3+/–COO− pairs on the material surfaces. With the aim of evaluating the feasibility of this functionalization strategy in HA shaped in different physical forms, HA 3D macroporous scaffolds were fabricated by rapid prototyping and then provided with zwitterionic character. The effect of the simultaneous presence of –NH3+/–COO−zwitterionic pairs on the surface of HA on its behaviour regarding bacterial adhesion was tested using E. coli as model bacteria. The in vitro biocompatibility of these materials was investigated with cultured human HOS cells. The results indicate that it is possible to provide HA shaped in different physical forms (particles, granules, coatings, dense blocks, 3D scaffolds, etc.) with bacterial anti-adhesive properties via the “zwitterionization” process without affecting its biocompatibility. These findings open up promising expectations in many clinical fields including dentistry, maxillofacial surgery and otolaryngology, where a decrease in the bacterial adherence onto the implant surface would reduce the infection rates after implantation surgery.

International audience; A novel, biocompatible, calcium-based coordination polymer was hydrothermally synthesized using as linker the bone antiresorptive bisphosphonate alendronate. Its structure was determined using single-crystal X-ray diffraction and characterized by chemical analysis, infrared spectroscopy (IR), X-ray powder diffraction (XRPD), solid state nuclear magnetic resonance (NMR) and thermogravimetric analysis (TGA). Its bioactivity was finally evaluated in vitro, revealing a very high stability towards simulated body fluid.

By employing solid-state nuclear magnetic resonance (NMR) spectroscopy, powder X-ray diffraction (PXRD), and scanning electron microscopy coupled with energy-dispersive X-ray (EDX) spectroscopy, we compare the biomimetic growth of calcium hydroxyapatite (HA) from an ordered mesoporous bioactive glass (MBG) in simulated body fluid (SBF) and buffered water solutions. For the latter medium, we also examine the effects of using two different MBG concentrations. We evaluate the predicting powers of PXRD and 31P NMR for directly quantifying the relative amounts of biomimetic amorphous calcium phosphate (ACP) and HA: we observe a very good agreement between the two analytical techniques. Thanks to their mesoporous channel system, fluids readily penetrate throughout sub-mm sized MBG grains, as evidenced by EDX. The latter revealed distinct element-mappings across the material after its exposure to SBF compared to water. Under our in vitro conditions involving relatively high MBG-loadings in the solutions, the HA formation reduces in SBF relative to buffered water, particularly for increasing MBG concentration. These features stem from a high [Ca2+]/[PO3−4] ratio resulting in the fluid medium, which retards the HA crystallization by inducing a rapid ACP precipitation and an accompanying depletion of phosphate ions in the solution. This has bearings on the design of bioactivity comparisons of bioglasses exhibiting significantly different cation compositions.

Novel 3D-macroporous biopolymer-coated hydroxyapatite foams are potential devices for the treatment of heavy-metal intoxication by ingestion. These foams are designed to exhibit a fast and efficient metal ion immobilization into the HA structure in acidic media. The capture process of metal ions is stable, not releasing any metal ion when the foams are soaked in clean basic media afterwards. These two steps mimic a digestion process.