The effect of varying Al 2 O 3 percentage in hydroxyapatite/Al 2 O 3 composite materials: Morphological, chemical and cytotoxic evaluation

Calcium Orthophosphate (CaPO4) Containing Composites for Biomedical Applications: Formulations, Properties, and Applications

The goal of this review is to present a wide range of hybrid formulations and composites containing calcium orthophosphates (abbreviated as CaPO4) that are suitable for use in biomedical applications and currently on the market. The bioactive, biocompatible, and osteoconductive properties of various CaPO4-based formulations make them valuable in the rapidly developing field of biomedical research, both in vitro and in vivo. Due to the brittleness of CaPO4, it is essential to combine the desired osteologic properties of ceramic CaPO4 with those of other compounds to create novel, multifunctional bone graft biomaterials. Consequently, this analysis offers a thorough overview of the hybrid formulations and CaPO4-based composites that are currently known. To do this, a comprehensive search of the literature on the subject was carried out in all significant databases to extract pertinent papers. There have been many formulations found with different material compositions, production methods, structural and bioactive features, and in vitro and in vivo properties. When these formulations contain additional biofunctional ingredients, such as drugs, proteins, enzymes, or antibacterial agents, they offer improved biomedical applications. Moreover, a lot of these formulations allow cell loading and promote the development of smart formulations based on CaPO4. This evaluation also discusses basic problems and scientific difficulties that call for more investigation and advancements. It also indicates perspectives for the future.

Effect of Ta2O5 content on the osseointegration and cytotoxicity behaviors in hydroxyapatite-Ta2O5 coatings applied by EPD on superelastic NiTi alloys

In the present study, the different contents of tantalum pentoxide (Ta₂O₅: 10, 15, 20 and 30 wt%) nanoparticles were introduced into the natural hydroxyapatite (nHA) coating structure on NiTi substrate through electrophoretic deposition (EPD) method. The phase compositions of coatings were perused before and after the sintering at 800 °C for 1 h by XRD. The incorporation of 30wt%Ta₂O₅ into nHA matrix induced the formation of undesirable soluble Ca₃(PO₄)₂ phase in composite coating. The FESEM images showed that the density of continuous nHA coating increased by compositing with Ta₂O₅. The maximum adhesion strength of 28.3 ± 0.7 MPa accomplished from the nHA-20 wt%Ta₂O₅ composite coating. The Ni ions concentration measurement results from the passivated-NiTi with nHA and nHA-(10, 15 and 20)wt%Ta₂O₅ coatings during 30 days of immersion in PBS clarified the positive role of Ta₂O₅ in decreasing the Ni leaching due to the lowering the open porosities of nHA structure. The biological response of the coating surfaces was assessed in vitro by cell culturing and MTS assay. By considering the morphology and density of adsorbed cells on each coating, the improved biocompatibility of nHA coating in the presence of Ta₂O₅ was justified by scrutinizing the surface roughness, wettability and charge. The highest cell attachment and proliferation on nHA-20 wt%Ta₂O₅ coating was related to owning the lowest roughness, wetting angle of 34^o ± 0.5 and the highest negative surface charge density. Also, the concentration of the highest negative charge density on nHA-20 wt%Ta₂O₅ coating surface in the SBF solution caused to the enhancement of the amount of the apatite nuclei through providing more sites to calcium absorption.

A renewable resource based carbon dot decorated hydroxyapatite nanohybrid and its fabrication with waterborne hyperbranched polyurethane for bone tissue engineering

Carbon dot decorated hydroxyapatite/water borne hyperbranched polyurethane nanocomposite.

Calcium Orthophosphate-Containing Biocomposites and Hybrid Biomaterials for Biomedical Applications

The state-of-the-art on calcium orthophosphate (CaPO4)-containing biocomposites and hybrid biomaterials suitable for biomedical applications is presented. Since these types of biomaterials offer many significant and exciting possibilities for hard tissue regeneration, this subject belongs to a rapidly expanding area of biomedical research. Through the successful combinations of the desired properties of matrix materials with those of fillers (in such systems, CaPO4 might play either role), innovative bone graft biomaterials can be designed. Various types of CaPO4-based biocomposites and hybrid biomaterials those are either already in use or being investigated for biomedical applications are extensively discussed. Many different formulations in terms of the material constituents, fabrication technologies, structural and bioactive properties, as well as both in vitro and in vivo characteristics have been already proposed. Among the others, the nano-structurally controlled biocomposites, those containing nanodimensional compounds, biomimetically fabricated formulations with collagen, chitin and/or gelatin, as well as various functionally graded structures seem to be the most promising candidates for clinical applications. The specific advantages of using CaPO4-based biocomposites and hybrid biomaterials in the selected applications are highlighted. As the way from a laboratory to a hospital is a long one and the prospective biomedical candidates have to meet many different necessities, the critical issues and scientific challenges that require further research and development are also examined.

Composites of Eu(3+)-doped calcium apatite nanoparticles and silica particles: comparative study of two preparation methods

We synthesized composites of Eu(3+)-doped calcium apatite (CaAp:Eu(3+)) nanoparticles and silica particles via two methods: (i) in situ synthesis of CaAp:Eu(3+) in the presence of silica particles and (ii) electrostatic adsorption of CaAp:Eu(3+) nanoparticles on silica particle surfaces. In both methods, submicrometer spherical silica particles were covered with CaAp:Eu(3+) nanoparticles without forming any impurity phases, as confirmed by X-ray diffractometry, Fourier-transform infrared spectroscopy, and scanning electron microscopy. In method i, part of the silica surface acted as a nucleation site for apatite crystals and silica particles were inhomogeneously covered with CaAp:Eu(3+) nanoparticles. In method ii, positively charged CaAp:Eu(3+) nanoparticles were homogeneously adsorbed on the negatively charged silica surface through electrostatic interactions. The bonds between the silica surface and CaAp:Eu(3+) nanoparticles are strong enough not to break under ultrasonic irradiation, irrespective of the synthetic method used. The composite particles showed red photoluminescence corresponding to 4f → 4f transitions of Eu(3+) under near-UV irradiation. Although the absorption coefficient of the forbidden 4f → 4f transitions of Eu(3+) was small, the red emission was detectable with a commercial fluorescence microscope because the CaAp:Eu(3+) nanoparticles accumulated on the silica particle surfaces.

Gelatin functionalized graphene oxide for mineralization of hydroxyapatite: biomimetic and in vitro evaluation

We report a facile modification of graphene oxide (GO) by gelatin to mimic charged proteins present in the extracellular matrix during bone formation. The bioinspired surface of GO-gelatin (GO-Gel) composite was used for biomimetic mineralization of hydroxyapatite (HA). A detailed structural and morphological characterization of the mineralized composite was performed. Additionally, MC3T3-E1 cells were cultured on the GO-Gel surfaces to observe various cellular activities and HA mineralization. Higher cellular activities such as cell adhesion, cell proliferation, and alkaline phosphatase activity (ALP) were observed on the GO-Gel surface compared with the GO or glass surface. The increase of ALP confirms that the proposed GO-Gel promotes the osteogenic differentiation of MC3T3-E1 cells. Moreover, the evidence of mineralization evaluated by scanning electron microscopy (SEM) and alizarin red staining (ARS) corroborate the idea that a native osteoid matrix is ultimately deposited. All these data suggest that the GO-Gel hybrids will have great potential as osteogenesis promoting scaffolds for successful application in bone surgery.

Biocomposites and hybrid biomaterials based on calcium orthophosphates

The state-of-the-art of biocomposites and hybrid biomaterials based on calcium orthophosphates that are suitable for biomedical applications is presented in this review. Since these types of biomaterials offer many significant and exciting possibilities for hard tissue regeneration, this subject belongs to a rapidly expanding area of biomedical research. Through successful combinations of the desired properties of matrix materials with those of fillers (in such systems, calcium orthophosphates might play either role), innovative bone graft biomaterials can be designed. Various types of biocomposites and hybrid biomaterials based on calcium orthophosphates, either those already in use or being investigated for biomedical applications, are extensively discussed. Many different formulations, in terms of the material constituents, fabrication technologies, structural and bioactive properties as well as both in vitro and in vivo characteristics, have already been proposed. Among the others, the nanostructurally controlled biocomposites, those containing nanodimensional compounds, biomimetically fabricated formulations with collagen, chitin and/or gelatin as well as various functionally graded structures seem to be the most promising candidates for clinical applications. The specific advantages of using biocomposites and hybrid biomaterials based on calcium orthophosphates in the selected applications are highlighted. As the way from the laboratory to the hospital is a long one, and the prospective biomedical candidates have to meet many different necessities, this review also examines the critical issues and scientific challenges that require further research and development.