Influence of nanoscale-modified apatite-type calcium phosphates on the biofilm formation by pathogenic microorganisms

Abstract

Nanoparticles (25–50 nm) of chemically modified calcium phosphates Ca10−x−y Mii xNay(PO4)6−z (CO3)z(OH)2 (Mii – Cu2+, Zn2+) were synthesized via a wet precipitation method at room temperature. The Fourier-transform infrared spectroscopy data confirmed the partial substitution of PO43−{\text{PO}}_{4}^{3-} → CO32−{\text{CO}}_{3}^{2-} (B-type) in apatite-type structure. The influence of prepared phosphates on biofilm formation by pathogenic microorganisms was investigated. It was found that the samples Na+, CO32−{\text{CO}}_{3}^{2-}-hydroxyapatite (HAP) and Na+, Zn2+, CO32−{\text{CO}}_{3}^{2-}-HAP (5–20 mM) had the highest inhibitory effect on biofilm formation by Staphylococcus aureus strains. The sample Na+, CO32−{\text{CO}}_{3}^{2-}-HAP had the slight influence on the formation of the biofilm by Pseudomonas aeruginosa, while for the samples Na+, Cu2+, CO32−{\text{CO}}_{3}^{2-}-HAP and Na+, Zn2+, CO32−{\text{CO}}_{3}^{2-}-HAP such an effect was not detected. According to transmission electron microscopy data, a correlation between the activity of synthesized apatite-related modified calcium phosphates in the processes of biofilm formation and their ability to adhere to the surface of bacterial cells was established. The prepared samples can be used for the design of effective materials with antibacterial activity for medicine.

Keywords

• apatite
• nanoparticles
• biofilm formation
• staphylococcus aureus
• pseudomonas aeruginosa