Development of Phosphatized Calcium Carbonate Biominerals as Bioactive Bone Graft Substitute Materials, Part II: Functionalization with Antibacterial Silver Ions

Abstract

Porous calcium phosphate (CaP) materials as bone graft substitutes can be prepared from Ca carbonate biomineral structures by hydrothermal conversion into pseudomorphic CaP scaffolds. The present study aims at furnishing such phosphatized Ca carbonate biomineral (PCCB) materials with antibacterial Ag ions in order to avoid perisurgical wound infections. Prior to this study, PCCB materials with Mg and/or Sr ions incorporated for stimulating bone formation were prepared from coral skeletons and sea urchin spines as starting materials. The porous PCCB materials were treated with aqueous solutions of Ag nitrate with concentrations of 10 or 100 mmol/L, resulting in the formation of Ag phosphate nanoparticles on the sample surfaces through a replacement reaction. The materials were characterized using scanning electron microscopy (SEM) energy-dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). In contact with Ringer`s solution, the Ag phosphate nanoparticles dissolved and released Ag ions with concentrations up to 0.51 mg/L, as shown by atomic absorption spectroscopy (AAS) analyses. In tests against Pseudomonas aeruginosa and Staphylococcus aureus on agar plates, antibacterial properties were similar for both types of Ag-modified PCCB materials. Concerning the antibacterial performance, the treatment with AgNO3 solutions with 10 mmol/L was almost as effective as with 100 mmol/L.

Phase-specific bioactivity and altered Ostwald ripening pathways of calcium carbonate polymorphs in simulated body fluid

“…15,16 This triggered a smaller series of detailed investigation on the formation mechanisms and on the exploitation of coralline calcium carbonate for biomedical applications. [17][18][19][20][21][22][23] These contributions evidenced that coralline calcium carbonate is a potential bone lling material with good osteoconductivity. 20,[24][25][26][27] However, the use of biogenic and thus pre-formed porous ceramic matrices comes at a price which made this general approach less attractive: they typically pose problems due to their meager mechanical integrity and loadbearing capabilities which arise due to their ungovernable porosity.…”

Development of Phosphatized Calcium Carbonate Biominerals as Bioactive Bone Graft Substitute Materials, Part I: Incorporation of Magnesium and Strontium Ions

“…For further development, additional modifications of these materials could take them even further toward multifunctional implants. For example, in a second part of the study presented here, the materials discussed will be additionally functionalized with Ag ions for an antibacterial effect that may reduce the risk of perisurgical wound infections [85].…”

Antibacterial Honeycomb Scaffolds for Achieving Infection Prevention and Bone Regeneration

“…Owing to these characteristics, CAp HC materials are osteoconductive and osteoinductive . Consequently, the CAp HC materials substantially surpass various calcium phosphate materials in osteogenesis. , Furthermore, in most previously reported porous materials, large portions of the macropores are closed, making modification of the pore surface with antibacterial substances difficult. − In contrast, modification of the pore surface with antibacterial substances is considered easy in HC materials with numerous uniaxial channels completely penetrating the material. In addition, the channels of the HC materials allow blood and tissue fluid to freely pass through the material, which inhibits bacterial colonization.…”