Cu ions and cetyltrimethylammonium bromide loaded into montmorillonite: a synergistic antibacterial system for bone scaffolds

Abstract

Developing a novel antibacterial material with highly effective and long-lasting antibacterial activity to prevent bacterial infection during or post bone scaffold transplantation is an urgent need for bone regeneration. In this study, a synergistic antibacterial system for a polyglycolic acid (PGA) scaffold was constructed by cation exchange of montmorillonite (MMT) with Cu²⁺ and then intercalation of cetyltrimethylammonium bromide (CTAB) into the interlayer of MMT. On one hand, the introduced Cu²⁺ enlarged the interlayer spacing of MMT, facilitating the intercalation of CTAB into the MMT interlayer to impart the antibacterial effect. On the other hand, the intercalation of CTAB into MMT shifted the surface potential of MMT from negative to positive, improving the bacterial adsorption capacity by electrostatic forces so that Cu²⁺ could act directly on the negatively charged bacteria. As a result, the bacterial adsorption rate of Cu²⁺ and CTAB modified MMT (Cu-CMMT) improved by 76.5% compared with that of MMT, which could be explained by the increased zeta potential from −26.1 to 19.7 mV. Besides, the scaffold with Cu-CMMT exhibited robust antibacterial activities against E. coli with an antibacterial rate of 98.1%, which was significantly higher than that of the scaffold with Cu²⁺ or CTAB modified MMT individually. The scaffold with Cu-CMMT exhibited the highest level of reactive oxygen species (ROS), which was attributed to the dilapidation of bacterial cells.