Hydrothermal Transformation of Eggshell Calcium Carbonate into Apatite Micro-Nanoparticles: Cytocompatibility and Osteoinductive Properties

• Published in: Nanomaterials (Basel, Switzerland) Switzerland), 2023-08, Vol.13 (16), p.2299
• Main Authors: Torres-Mansilla, Adriana, Álvarez-Lloret, Pedro, Fernández-Penas, Raquel, D’Urso, Annarita, Baldión, Paula Alejandra, Oltolina, Francesca, Follenzi, Antonia, Gómez-Morales, Jaime
• Format: Article
• Language: English
• Subjects: Aluminum; Apatite; Biocompatibility; Biomedical materials; Bones; Calcification; Calcite; Calcium carbonate; Calcium phosphates; Cell differentiation; Circular economy; Crystal structure; cytocompatibility; Dentistry; Differentiation (biology); Drinking water; Egg shells; Eggshells; hydrothermal conversion; Mechanical properties; Mesenchymal stem cells; Nanoparticles; organic matrix; Organic matter; Osteogenesis; osteogenic differentiation; Osteosarcoma; Osteosarcoma cells; Potassium phosphate; Potassium phosphates; Proteins; Reagents; Scanning electron microscopy; Stem cells; Thermal properties; Tissue engineering
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano13162299

The eggshell is a biomineral consisting of CaCO3 in the form of calcite phase and a pervading organic matrix (1–3.5 wt.%). Transforming eggshell calcite particles into calcium phosphate (apatite) micro-nanoparticles opens the door to repurposing the eggshell waste as materials with potential biomedical applications, fulfilling the principles of the circular economy. Previous methods to obtain these particles consisted mainly of two steps, the first one involving the calcination of the eggshell. In this research, direct transformation by a one-pot hydrothermal method ranging from 100–200 °C was studied, using suspensions with a stoichiometric P/CaCO3 ratio, K2HPO4 as P reagent, and eggshells particles (Ø < 50 μm) both untreated and treated with NaClO to remove surface organic matter. In the untreated group, the complete conversion was achieved at 160 °C, and most particles displayed a hexagonal plate morphology, eventually with a central hole. In the treated group, this replacement occurred at 180 °C, yielding granular (spherulitic) apatite nanoparticles. The eggshell particles and apatite micro-nanoparticles were cytocompatible when incubated with MG-63 human osteosarcoma cells and m17.ASC murine mesenchymal stem cells and promoted the osteogenic differentiation of m17.ASC cells. The study results are useful for designing and fabricating biocompatible microstructured materials with osteoinductive properties for applications in bone tissue engineering and dentistry.