Rifampin-loaded Mesoporous Silica Nanoparticles Improved Physical and Mechanical Properties and Biological Response of Acrylic Bone Cement.

Background: Acrylic bone cement, which is used to fix implants in the knee and hip, is prone to contamination with various types of infections. Adding small amounts of different antibiotics to the cement can help prevent and treat infections. Rifampin antibiotic has been added to bone cement to create an appropriate antimicrobial response in the treatment of resistant coagulase-negative staphylococci (CoNS) biofilms, but there are some challenges such as reducing mechanical properties and prolonging the setting time of the cement. Loading the antibiotic in the nanoparticle could eliminate these challenges.

Methods: In this study, rifampin-loaded mesoporous silica nanoparticles (MSNs) were added to bone cement, and the polymerization components, mechanical properties, drug release, antibacterial activity, and cellular response were investigated and compared with commercial pure cement and the cement containing free rifampin.

Results: Loading rifampin into MSN improved compressive strength by 57.52%. Cement containing rifampin loaded into MSN showed remarkable success in antibacterial activity. The growth inhibition zone created by it in the culture medium of Staphylococcus aureus and CoNS was 15.44% and 11.8% greater, respectively, than in the cement containing free rifampin. In other words, according to the results of spectrophotometric analysis of cement samples over 5 weeks, MSNs caused a 33.2 ± 0.21-fold increase in rifampin washout from the cement. Cellular examination of the cement containing rifampin loaded into MSN compared to commercial pure cement showed an acceptable level of cell viability.

Conclusion: Rifampin loading in MSN limited the reduction of cement strength. It also improved the drug release pattern and prevented antibiotic resistance.