Enzymatic regulation of CoFe LDH through samarium doping for rapid ROS-induced membrane disruption and inactivation of pathogenic bacteria

The prevalence of bacterial contamination in living environments causes a serious health threat, requiring effective strategies to control associated infections. Accordingly, engineered nanomaterials are regarded as promising alternatives for combating pathogenic microorganisms and antibiotic-resistant bacteria. In this work, samarium (III) cations (Sm³⁺)-doped CoFe ternary layered double hydroxide (Sm-CoFe LDH) was synthesized via the co-precipitation method with Sm³⁺ substitution (0.0–30%). The synthesized nanomaterials were characterized utilizing various techniques, suggesting the successful incorporation of Sm³⁺ into the CoFe LDH structure up to a maximum content of 20%. The kinetic investigations represented the enhanced-oxidase activity of 20% Sm³⁺ doped LDH (Sm20-CoFe LDH), thereby enabling more efficient generation of reactive oxygen species (ROS). Based on its superior oxidase-like catalytic activity, Sm20-CoFe LDH was evaluated for potential antimicrobial activity, demonstrating strong antibacterial performance with minimum bactericidal concentrations (MBCs) of 50.6 μg mL⁻¹ and 41.4 μg mL⁻¹ against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), respectively. Radical scavenging tests revealed that singlet oxygen (¹O₂) and superoxide anion radicals (^•O₂⁻) were the dominant factors responsible for the ROS-induced bacterial inactivation. Bacterial imaging and double-staining methods revealed a membrane-mediated mechanism of Sm20-CoFe LDH.