Ion release and antibacterial assessment of copper-containing hydroxyapatite and biphasic calcium phosphates

Abstract

Copper-containing hydroxyapatite (CuHA) is hypothesized to be an effective approach to hinder orthopedic infection. Copper (Cu) is well regarded for its antibacterial potential yet remains understudied in bioceramics. Herein, a series of CuHA were evaluated by probing the Cu²⁺ ion using electron paramagnetic resonance (EPR). Additionally, particle size, surface area, and crystallinity measurements were performed. CuHA was heat-treated to form Cu-containing biphasic calcium phosphate (CuBCP), which enabled Cu release in aqueous solution to reach a maximum of 0.108 + 0.004 mg/L per 1m² powder compared to its CuHA counterpart, which showed no Cu release per 1m² powder. Agar diffusion and time-based bacterial broth analyses were conducted against gram-positive and gram-negative strains of bacteria for CuHA and CuBCP with results indicating potential bacteriostatic effects. The material that released the highest amount of Cu into aqueous solution also exhibited the largest inhibitory effect against S. Aureus (broth analyses) indicating a potential correlation.