Effect of polymerizable quaternary ammonium monomer MEIM-x's alkyl chain length and content on bone cement's antibacterial activity and physicochemical properties.

Abstract

Quaternary ammonium monomers with N-alkyl chain length varied from 6 to 18, namely MEIM-x(x = 6-18), were incorporated into acrylic bone cements to prepare antibacterial bone cements. With the increasing of MEIM-x's alkyl chain length, the MEIM-x monomers' minimum inhibitory concentrations (MIC) decreased to 8 μg/mL and 2 μg/mL (MEIM-14, for E. coli and S. aureus, respectively) at first and then increased. The 50% hemolytic concentrations (HC50) decreased monotonously with the increasing of alkyl chain length. The bone cements contained 2% and 5% of long-chain MEIM-x (x ≥ 10) showed significant antibacterial activity against E. coli and S. aureus, while the bone cements contained short-chain MEIM-x(x < 10) showed a weaker activity. Overall, adding 2% of MEIM-x had acceptable influences on the bone cements' properties in terms of doughing time, setting time, peak temperature, solubility, fluid uptake, compressive strength, flexural strength, flexural modulus, hemolysis and cytotoxicity, but adding 5% of MEIM-x impaired the bone cements' mechanical properties and hemolysis significantly.