Hydroxyapatite (HA) is widely used in biomedical applications due to its biocompatibility and chemical similarity to the mineral phase of bone; however, its low mechanical strength limits its structural use. In this work, HA ceramics with different Mg additions (0, 0.5, 1, 3, 5, and 10% by weight) were prepared using the powder processing technique. The mixtures were homogenized, conformed and sintered at 1100 °C. The incorporation of intermediate Mg concentrations produced an increase in fracture toughness compared to pure HA. The best mechanical performance was obtained with the formulation containing 5% Mg by weight, achieving a hardness of 319 HV, a porosity of 12.92% and a fracture toughness of 4.06 MPa·m0.5, comparable to those reported for human cortical bone, indicating its potential for applications in moderately loaded bone implants. The findings indicate that magnesium functions as a reinforcing component in the ceramic matrix, mitigating critical defects and thereby contributing to the improved toughness of Mg-containing hydroxyapatite ceramics. The polarization resistance results show that the incorporation of low fractions by weight of magnesium (1% Mg) adjusts the electrochemical behavior of the material, while higher increases in its concentration cause a deterioration of this property.
Hydroxyapatite (HAp), a calcium phosphate material that closely resembles the mineral phase of natural bone, is widely studied due to its biocompatibility, bioactivity, and osteoconductivity, making it an important biomaterial in biomedical applications. With increasing demand for HAp-based materials, considerable research has focused on developing synthesis methods to tailor its structural and functional properties. Variations in synthesis strategies can significantly influence crystallinity, particle size, porosity, and surface characteristics of HAp, which in turn affect biological performance. Among biogenic sources, bovine-derived HAp has received attention due to its compositional similarity to natural bone mineral. Several studies report that, depending on extraction and processing conditions, bovine HAp can exhibit favorable crystallinity, mechanical stability, and porous architecture; however, these properties remain highly dependent on preparation parameters and require careful control. This review summarizes the synthesis of bovine HAp using conventional methods (thermal decomposition and hydrothermal techniques), hybrid approaches (calcination combined with vibro-milling and alkaline heat treatment, as well as ultrasonic-assisted spray drying), and emerging techniques such as subcritical water processing, transferred arc plasma, and annealing, each offering varying degrees of control over physicochemical properties. Characterization techniques, including X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM, TEM), and energy-dispersive X-ray spectroscopy (EDX), are discussed for evaluating crystallinity, morphology, and elemental composition respectively. Furthermore, the biomedical applications of bovine-derived HAp are reviewed, including bone tissue engineering, bone grafting, dental repair, drug delivery, bioactive coatings, and antibacterial activity. While bovine-derived HAp shows promise as a sustainable and multifunctional biomaterial, further studies are required to address challenges related to processing consistency, long-term performance, and clinical translation.
Bioactive strength is crucial for load-bearing biomaterials. Although hydroxyapatite is highly biocompatible, it has brittleness and a lack of dual-ion substitution in polymeric scaffold studies. In this work, Ce/Fe doped HAP was synthesized by chemical precipitation and solvent cast onto PLA films. Phase-pure HAP with no secondary phases and a crystallite size decrease from 2.58-0.85 nm following doping was confirmed by XRD. Its structural integrity was confirmed by FTIR, which showed the distinctive phosphate and hydroxyl bands 550-627, 964.7, 1026, 3441 and 650 cm-1. While EDAX confirmed the distribution of Ca, P, Ce and Fe with Ca/P ratios between 1.64 and 1.67. SEM showed homogeneous morphology. Nanorod structures measuring roughly 50-100 nm in length and 15-20 nm in width were revealed by TEM investigation. Enhanced surface reactivity was indicated by a rise in BET surface area from 89.17-105.82 m2/g and pore-volume from 0.411-0.499 cm3/g. Rapid apatite-nucleation and thick Ca/P-rich layer development were encouraged by in vitro bioactivity in SBF. Because enhanced dispersion stability and decreased particle agglomeration promote cellular interaction and lessen harmful effects, DLS analysis revealed nanosized with stable zeta potential, which correlates with the reported MG-63 cell viability reaching 84%. Excellent hemocompatibility was demonstrated by the fabricated dual ion doped HAP/PLA composite. Microhardness improved by almost 85%, rising from 73 HV to 135 HV. Ce/Fe doped HAP sample possess superior anti-microbial efficiency against both gram (+)'ve and gram (-)'ve strains. These findings demonstrate the complementary effects of polymer reinforcement and dual-ion doping, suggesting great promise for Osteo-regenerative applications.
Sabitha R, Kumaraguru S, Issathul Riswan M et al.· Journal of Biomaterials Scie...· 0 citations
Biomedical devices for bone tissue repair require materials with a balanced combination of printability, structural integrity, and biological performance. Their fabrication is increasingly shifting toward additive manufacturing, in which thermoplastic biodegradable polymers, particularly poly(lactic acid) (PLA), serve as matrices. In this study, PLA composite filaments with varying hydroxyapatite (HAp) contents (0, 5, 10, 20, and 30 wt%) were fabricated via a solvent-assisted non-solvent-induced precipitation method and evaluated for extrusion-based bone tissue engineering applications. HAp content significantly influenced the physicochemical, rheological, mechanical, and biological performance of the composites: increasing HAp loading reduced filler dispersion homogeneity and, at 30 wt%, pronounced agglomeration and microvoid formation. Thermal analysis demonstrated that the incorporation of HAp did not significantly affect the glass transition temperature of PLA, which remained nearly constant regardless of HAp content. However, the presence of HAp shifted the cold crystallization temperature to higher values, suggesting delayed cold crystallization during heating. Intermediate HAp incorporation (5-10 wt%) provided the most favourable balance between homogeneous filler dispersion, mechanical reinforcement, and osteoblastic response, with PLA-HAp10 showing enhanced ALP activity and osteogenic gene expression together with reliable filament formation and scaffold printability. In contrast, 20 wt% HAp approached the upper composition-processing threshold of the system, while 30 wt% HAp compromised structural homogeneity and extrusion reliability. These findings highlight the importance of controlling HAp loading to achieve a balanced combination of processability, structural integrity, and osteogenic performance in PLA-based biomaterials.
Lukošiūnas Jokūbas, Šaparajavaitė Gabrielė, Dambrauskas Tadas et al.· International Journal of Bio...· 0 citations
In this study, a biphasic calcium phosphate cement (BCPC) was fabricated, combining the biocompatibility of hydroxyapatite (HA) and the biodegradability of β-tricalcium phosphate (β-TCP), and processed by robocasting, an extrusion-based technique, for bone tissue engineering applications. Despite its well-known biological performance, this material is brittle - mainly used as bone graft substitutes due to its limited mechanical strength. To overcome this limitation, graphene nanoplatelets (GNPs) were incorporated into the cement as a reinforcing filler. Their addition not only enhanced the mechanical strength but also improved the rheological behavior of BCPC pastes, resulting in better printability during the robocasting process. In particular, the incorporation of GNPs reduced the elastic modulus of the pastes, facilitating extrusion. Bars with and without microporosity were 3D-printed and subsequently evaluated by flexural testing. The flexural strength of microporous BCPC samples increased from 4.2 MPa (0% GNP) to 5.9 MPa (2% GNP), representing a 40% improvement. Although dense samples also exhibited higher strength with GNP addition, the difference was not statistically significant. Distinct stress-strain curve profiles obtained during bending tests revealed the influence of the printed architecture on the mechanical response of the printed parts. The flexural modulus followed the opposite trend to the flexural strength, showing a significant increase in dense parts containing GNP, while no substantial change was observed in the microporous counterparts. Overall, all measured mechanical properties fell within the range reported for trabecular bone substitution applications.
S. Roedel, S. Tadier, M. Fredel et al.· Journal of The Mechanical Be...· 0 citations
Hydroxyapatite is widely used as a bioceramic material in orthopedic and dental field because of its exceptional biocompatibility and bioactivity. Hydroxyapatite (HAp) doped with several mineral ions has been frequently reported to further enhance its bioactive nature. Several studies indicate that biological waste materials can serve as calcium sources for hydroxyapatite synthesis, with eggshells being one such promising source. In the present work, two types of hydroxyapatite were synthesized: pure hydroxyapatite and 5% magnesium-doped hydroxyapatite (based on weight percentage). Laboratory-grade calcium hydroxide was used for synthetic HAp, while eggshell powder was employed for eggshell-derived HAp. The activity of the developed materials in biological environment was assessed using in vitro methods. Porous ceramic blocks were fabricated by compacting the powders using a hydraulic press and sintering them at 950°C. Powder samples calcined at 800°C were analysed by X-ray diffraction (XRD) to assess the lattice parameters and functional groups identification was done by Fourier transform infrared spectroscopy (FTIR) to identify. Apparent porosity was determined using Archimedes’ principle, confirming the presence of pores in the pellets. Hemolysis studies demonstrated that the synthesized materials are hemocompatible. Simulated body fluid (SBF) studies confirmed the appearance of apatite layer on the sintered pellets, establishing the bioactive and interactive nature of the developed materials.
Subhasis Nath, S. K. Samanta, S. Debnath et al.· Journal of Polymer & Composi...· 0 citations
Beta-tricalcium phosphate (β-TCP) is widely utilized in biomedical applications due to its outstanding biocompatibility and strong osteoconductive properties. Its high bioresorbability in the physiological environment allows the implanted material to undergo slow, controlled degradation over time, facilitating a gradual replacement with the body's native tissue, making it particularly suitable for bone reconstruction. A large number of studies have investigated the synthesis of β-TCP using a variety of chemical approaches, including both dry and wet approaches. Each method has distinct advantages and limitations, and these significantly influence crystallite size, crystallinity, densification behavior, shrinkage, morphology, and the overall properties of the final product. For surgical implants that require high mechanical strength, achieving high ceramic density is essential. The use of nano-sized β-TCP powders as starting materials has proven effective in producing dense ceramics. Furthermore, to preserve the resorbability of β-TCP, it is critical to obtain a pure phase. For these reasons, investigations into β-TCP synthesis have steadily increased, with a particular focus on tailoring its crystallographic properties. This review focuses on six methods for synthesizing β-TCP for bone grafting materials, dental implant applications, and bone tissue engineering. Traditional β-TCP synthesis is often criticized for generating large, non-uniform particles and secondary phases at high temperatures. In contrast, methods such as sol–gel, hydrothermal, solution combustion, and chemical precipitation are preferred for their superior control over the final product properties. We summarize the available information on each synthesis process, including benefits and drawbacks.
T. Akter, M. Habibur Rahman, Md. Shadat Hossain et al.· RSC Advances· 0 citations