Physicochemical degradation of calcium magnesium phosphate (stanfieldite) based bone replacement materials and the effect on their cytocompatibility.

Regenerative bone implants should be completely replaced by new bone within a period of time corresponding to the growth rate of native bone. To meet this requirement, suitable biomaterials must be biodegradable and promote osteogenesis. The combination of slowly degrading but osteoconductive calcium phosphates (CPs) with rapidly degrading and mechanically more resilient magnesium phosphates represents a promising material class for this purpose.

Corrigendum to "Degradation of 3D-printed magnesium phosphate ceramics in vitro and a prognosis on their bone regeneration potential" [Bioact. Mater. 19 (2023) 376-391/22].

[This corrects the article DOI: 10.1016/j.bioactmat.

Degradation of 3D-printed magnesium phosphate ceramics and a prognosis on their bone regeneration potential.

Regenerative bone implants promote new bone formation and ideally degrade simultaneously to osteogenesis. Although clinically established calcium phosphate bone grafts provide excellent osseointegration and osteoconductive efficacy, they are limited in terms of bioresorption. Magnesium phosphate (MP) based ceramics are a promising alternative, because they are biocompatible, mechanically extremely stable, and degrade much faster than calcium phosphates under physiological conditions.

Osteoclast and osteoblast response to strontium-doped struvite coatings on titanium for improved bone integration.

To develop implants with improved bone ingrowth, titanium substrates were coated with homogeneous and dense struvite (MgNH4PO4·6H2O) layers by means of electrochemically assisted deposition. Strontium nitrate was added to the coating electrolyte in various concentrations, in order to fabricate Sr-doped struvite coatings with Sr loading ranging from 10.6 to 115 μg/cm2.

Nanotopographical Coatings Induce an Early Phenotype-Specific Response of Primary Material-Resident M1 and M2 Macrophages.

Implants elicit an immunological response after implantation that results in the worst case in a complete implant rejection. This biomaterial-induced inflammation is modulated by macrophages and can be influenced by nanotopographical surface structures such as titania nanotubes or fractal titanium nitride (TiN) surfaces. However, their specific impact on a distinct macrophage phenotype has not been identified.

Effect of strontium substitution on the material properties and osteogenic potential of 3D powder printed magnesium phosphate scaffolds.

3D powder printing is a versatile method for the fabrication of individual bone implants and was used for the processing of in vivo degradable ceramic scaffolds based on ammonium magnesium phosphate hexahydrate (struvite). In this study, synergetic effects could be achieved by the substitution of magnesium phosphate cements with strontium carbonate. This substitution resulted in 8.

Cu, Co and Cr doping of a calcium phosphate cement influences materials properties and response of human mesenchymal stromal cells.

The application of biologically active metal ions to stimulate cellular reactions is a promising strategy to accelerate bone defect healing. Brushite-forming calcium phosphate cements were modified with low doses of Cu, Co and Cr. The modified cements released the metal ions in vitro in concentrations which were shown to be non-toxic for cells.

Reaction kinetics of dual setting α-tricalcium phosphate cements.

Addition of ductile polymers to calcium-deficient hydroxyapatite (CDHA)-forming bone cements based on α-tricalcium phosphate (α-TCP) is a promising approach to improve the mechanical performance of α-TCP cements and extend their application to load-bearing defects, which is else impeded by the brittleness of the hardened cement. One suitable polymer is poly-(2-hydroxyethylmethacrylate) (p-HEMA), which forms during cement setting by radical polymerisation of the monomer. In this study the hydration kinetics and the mechanical performance of α-TCP cements modified with addition of different HEMA concentrations (0-50 wt% in the cement liquid) was investigated by quantitative in situ XRD and four-point bending tests.

Additive manufacturing of scaffolds with sub-micron filaments via melt electrospinning writing.

The aim of this study was to explore the lower resolution limits of an electrohydrodynamic process combined with direct writing technology of polymer melts. Termed melt electrospinning writing, filaments are deposited layer-by-layer to produce discrete three-dimensional scaffolds for in vitro research. Through optimization of the parameters (flow rate, spinneret diameter, voltage, collector distance) for poly-ϵ-caprolactone, we could direct-write coherent scaffolds with ultrafine filaments, the smallest being 817 ± 165 nm.

Fabrication of individual alginate-TCP scaffolds for bone tissue engineering by means of powder printing.

The development of polymer-calcium phosphate composite scaffolds with tailored architectures and properties has great potential for bone regeneration. Herein, we aimed to improve the functional performance of brittle ceramic scaffolds by developing a promising biopolymer-ceramic network. For this purpose, two strategies, namely, direct printing of a powder composition consisting of a 60:40 mixture of α/β-tricalcium phosphate (TCP) powder and alginate powder or vacuum infiltration of printed TCP scaffolds with an alginate solution, were tracked.

Plasma-assisted hydrophilization of cochlear implant electrode array surfaces enables adhesion of neurotrophin-secreting cells.

Objective: To evaluate plasma treatment for enhancing the biocompatibility of cochlear implant (CI) silicone surfaces, thus allowing colonization with human adipose-derived stem cells (hASCs) that are known to provide neurotrophic support.

Methods: Silicone samples and CI electrode arrays were treated with 4 low-pressure plasmas of different characteristics. The hydrophilicity of plasma-treated and control surfaces as well as the adherence and morphology of hASCs were assessed.

Physical and chemical characterization of Ag-doped Ti coatings produced by magnetron sputtering of modular targets.

Silver-doped Ti films were produced using a single magnetron sputtering source equipped with a titanium target containing implemented silver modules under variation of bias voltage and substrate temperature. The Ti(Ag) films were characterized regarding their morphology, contact angle, phase composition, silver content and distribution as well as the elution of Ag(+) ions into cell media. SEM and AFM pictures showed that substrate heating during film deposition supported the formation of even and dense surface layers with small roughness values, an effect that could even be enforced, when a substrate bias voltage was applied instead.

Direct 3D powder printing of biphasic calcium phosphate scaffolds for substitution of complex bone defects.

The 3D printing technique based on cement powders is an excellent method for the fabrication of individual and complex bone substitutes even in the case of large defects. The outstanding bone remodeling capacity of biphasic calcium phosphates (BCPs) containing hydroxyapatite (HA) as well as tricalcium phosphate (TCP) in varying ratios makes the adaption of powder systems resulting in BCP materials to this fabrication technique a desirable aim. This study presents the synthesis and characterization of a novel powder system for the 3D printing process, intended for the production of complexly shaped BCP scaffolds by a hydraulic setting reaction of calcium carbonate and TCP with phosphoric acid.

Chemical characterization of hydroxyapatite obtained by wet chemistry in the presence of V, Co, and Cu ions.

A model system for the precipitation of hydroxyapatite (HA) from saturated solutions at basic pH was utilized to investigate the effects of V, Co, and Cu ions on crystallography and stoichiometry of the produced apatites. X-ray diffraction (XRD) was applied to analyze phase composition and crystallinity of powders obtained with different metal ion concentrations and annealed at different sintering temperatures. This procedure used the temperature-dependent phase transitions and decompositions of calcium phosphates to analyze the particular influences of the metal ions on apatite mineralization.

Low temperature fabrication of spherical brushite granules by cement paste emulsion.

Secondary protonated calcium phosphates such as brushite (CaHPO(4)·2H(2)O) or monetite (CaHPO(4)) have a higher resorption potential in bone defects than sintered ceramics, e.g. tricalcium phosphate or hydroxyapatite.

The effect of Cu(II)-loaded brushite scaffolds on growth and activity of osteoblastic cells.

Bone substitute materials such as calcium phosphate cements (CPC) are frequently used as growth factor carriers for the stimulation of osteoblast-formation around an implant. However, biological modification based on delicate protein factors like extracellular matrix proteins or growth factors is subject to a number of shortcomings like the need for storage below room temperature and cost of production. The aim of this study was to investigate ionic modification as an alternative bioinorganic route for implant modification.

Hard implant coatings with antimicrobial properties.

Infection of orthopaedic implants often leads to inflammation immediately after surgery and increases patient morbidity due to repetitive operations. Silver ions have been shown to combine good biocompatibility with a low risk of inducing bacterial resistance. In this study a physical vapour deposition system using both arc deposition and magnetron sputtering has been utilized to produce silver ion doped TiN coatings on Ti substrates.

Injectability and mechanical properties of magnesium phosphate cements.

Up to now magnesium phosphate cements are mainly being utilized in wastewater treatment due to their adsorptive properties. Recently they also have been shown to have a high potential as degradable biocements for application as replacement materials for bone defects. In comparison to degradable calcium phosphate cements they have the advantage of setting at neutral pH, which is favorable in biological environment.

Strontium modified biocements with zero order release kinetics.

Strontium-substituted beta-TCP with the general formula Ca((3-x))Sr(x)(PO(4))(2) (0 View Article and Find Full Text PDF