July 14, 2025 | Ceramics International |
Conducted by the University of Coimbra, Portugal, the study focused on synthesizing hydroxyapatite (HAp)—a calcium phosphate-based bioceramic—through an environmentally friendly sol-gel method. The researchers incorporated extracts from Hylocereus undatus cladodes as a natural template, aiming to develop an environmentally friendly synthesis route.
Thermal analysis (TGA/DSC) revealed a clear sequence of water evaporation, lattice water loss, HAp formation, and dehydroxylation. X-ray diffraction and Raman spectroscopy confirmed the phase composition and showed that residual NaNO3, initially present, was significantly reduced by a post-synthesis washing step. Scanning electron microscopy demonstrated that particle morphology was influenced by extract concentration and heat treatment, with higher extract levels promoting equiaxed particles and lower levels leading to rod-like structures, both relevant for biomedical use.
Impedance spectroscopy showed that dielectric properties were strongly frequency-dependent, with all samples displaying typical dielectric behavior. One formulation (12wHT400) met the desired performance criteria across multiple frequencies, combining a dielectric constant of 18.5–22.0, low dielectric losses, and minimal conductivity, indicating strong potential for long-term polarization retention.
These findings suggest that plant-extract-assisted sol-gel synthesis offers a sustainable method for producing hydroxyapatite with promising structural and functional characteristics for biomedical applications.
