Boron-doped Biphasic Hydroxyapatite/β-Tricalcium Phosphate for Bone Tissue Engineering.

Prior research has shown that hydroxyapatite (HT) and β-tricalcium phosphate (β-TCP) are widely used in bone grafting due to their osteoconductive properties. However, the structural and functional limitations of these materials remain a challenge in tissue engineering. It was already known that elemental doping can influence the physicochemical properties of biomaterials, but the specific effects of boron on HT/β-TCP composites were not fully understood. This gap motivated researchers to explore how incremental boron addition affects the crystal structure, porosity, and bioactivity of HT/β-TCP. No prior work had resolved the optimal boron concentration for enhancing mechanical and biological performance in these composites. The need to improve scaffold properties for bone regeneration remains an open area of investigation. Studies have suggested that boron may influence crystal growth and surface reactivity, but the extent of these effects in biphasic systems was unclear. This uncertainty drove the current study to synthesize and analyze boron-doped HT/β-TCP composites. The findings aim to clarify how boron incorporation alters the material's structure and biological interactions.

The aim of this study was to synthesize boron-doped hydroxyapatite/tricalcium phosphate composites and evaluate how incremental boron addition affects their structural, mechanical, and biological properties. Researchers sought to determine the optimal boron concentration that enhances bioactivity and mechanical performance without causing cytotoxicity. The specific problem addressed was the lack of understanding about how boron influences the crystal structure, porosity, and cell response of HT/β-TCP composites. The motivation stemmed from the need to improve scaffold materials for bone tissue engineering. By systematically varying boron content, the study aimed to identify the concentration that maximizes beneficial properties. The researchers also aimed to compare their findings with existing literature to validate their synthesis approach. A key objective was to assess the material's potential for use in composite bone tissue constructs. The study's results could inform the design of next-generation bone graft materials.

Boron-doped hydroxyapatite/tricalcium phosphate composites were synthesized using a wet precipitation and microwave reflux method. The composites were sieved to obtain particles smaller than 70 micrometers and analyzed for structural properties. X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy were used to assess crystal structure and functional group changes. The total surface area and mesoporosity of the samples were measured using gas adsorption techniques. Scanning electron microscopy (SEM) was employed to evaluate grain morphology and size distribution. Mechanical hardness was quantified using a Vickers hardness test. Bioactivity was assessed by measuring calcium phosphate deposition and protein adsorption on the composite surfaces. Cell culture experiments were conducted to evaluate alkaline phosphatase activity, intracellular calcium and phosphate storage, and protein accumulation. Cytotoxicity was assessed by measuring cell viability relative to a control group.

The highest crystallinity (95.78 ± 2.08%) and crystallite size (103.39 ± 23.47 nm) were observed in the 5BHT sample. Boron addition increased the total surface area (4.05 ± 0.82 m²/g) and mesoporosity (23.90 ± 7.92 μL/g) in the 10BHT sample. The grain size decreased to 0.21 ± 0.06 μm in the 5BHT sample, indicating finer particle formation. Mechanical hardness reached 10.51 ± 0.86 GPa in the 10BHT sample. The highest calcium phosphate deposition and protein adsorption (135.29 ± 29.58 μg) were observed on the 10BHT sample. Alkaline phosphatase activity was highest at 4.80 ± 0.40 M_ALP/ng_DNA.min in the 5BHT sample. Intracellular calcium storage reached 23.61 ± 0.68 g/g_DNA in the 5BHT sample. Cell viability remained at 128 ± 18% in the 5BHT sample, indicating no cytotoxicity.

The authors propose that boron incorporation enhances the structural and biological properties of HT/β-TCP composites without causing cytotoxicity. The findings suggest that 5BHT samples demonstrate optimal performance in terms of crystallinity, porosity, and bioactivity. The study's results indicate that boron addition can improve mechanical hardness and surface reactivity of the composites. The researchers suggest that the 5 mol% boron concentration is most effective for enhancing material properties. The observed increase in protein adsorption and calcium phosphate deposition supports the material's potential for bone regeneration. The study's results align with prior work but demonstrate a higher boron incorporation than previously reported. The authors conclude that the 5BHT samples have high potential for use in composite bone tissue constructs. These findings may guide future scaffold development for regenerative medicine applications.