Antibacterial, mechanical and curing properties of PMMA bone cement loaded with copper nanoparticles

Periprosthetic joint infection (PJI), a challenging complication of arthroplasty, is usually treated/managed using antibiotic-loaded PMMA bone cement. However, this cement has many shortcomings, such as a low cumulative amount of the antibiotic released by the time the release is exhausted and ineffectiveness against some bacteria that are present in many PJI cases, such as methicillin-resistant Staphylococcus aureus (S. aureus). As such, there are many ongoing research programs focus on developing alternative cement formulations without compromising their mechanical and curing properties. The present study evaluates the antimicrobial, mechanical, and curing performance of PMMA bone cement loaded with 0.5, 1.0, or 1.5 wt.% Cu nanoparticles (Cu NPs) against Escherichia coli (E. coli) and S. aureus (concentration: 2.0 × 10⁶, 3.0 × 10⁶, and 7.1 × 10⁶ CFU/mL). Analysis of the nanoparticles using scanning electron microscopy (SEM), X-ray diffraction (XRD), and dynamic light scattering (DLS) found they were nanocrystalline and had a mean hydrodynamic diameter of 114 nm. Evaluations of the antimicrobial performance of the cement, using the Kirby-Bauer disc diffusion method, showed that, for a given combination of bacterial species and concentration, the diameter of the inhibition zone on cement specimens increased with an increase in Cu NPs loading of the cement. The compressive testing revealed that the incorporation of Cu NPs did not significantly affect the compressive strength or elastic modulus of the cement. In addition, a decrease in the maximum curing temperature was observed with an increase in Cu NPs loading, while the setting time remained without significant differences. These findings suggest that a PMMA bone cement loaded with either 1.0 or 1.5 wt.% Cu NPs may be suitable for the treatment and management of PJI. Future studies of this cement are warranted.