Composições nanoestruturadas de cloreto de benzalcônio com β-ciclodextrina e hidroxipropil-βciclodextrina: síntese, caracterização físico-química e avaliação da interação com Staphylococcus aureus

Abstract

hermodynamic, colloidal, computational, and microbiological properties, as well as their potential antimicrobial applications. The inclusion complexes were prepared by complexation followed by lyophilization and characterized by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric and differential thermal analyses (TGA/DTA), proton nuclear magnetic resonance (1H NMR), two-dimensional NOESY experiments, isothermal titration calorimetry (ITC), dynamic light scattering (DLS), zeta potential, electrical impedance spectroscopy (EIS), and molecular modeling. In addition, microbiological assays were performed to determine the minimum inhibitory concentration (MIC), evaluate the eradication of preformed biofilms, and investigate the interaction of the systems with Staphylococcus aureus bacterial membranes. The results provided consistent evidence for the formation of inclusion complexes, as confirmed by the spectroscopic, thermal, structural, and thermodynamic changes observed using the different analytical techniques. Calorimetric analyses demonstrated that complex formation occurred spontaneously and was predominantly entropy-driven, while molecular modeling confirmed the stability of the complexes and elucidated the main molecular encapsulation mechanisms. Colloidal characterization revealed the formation of stable supramolecular nanoaggregates in aqueous solution. In the biological assays, the complexed systems exhibited antimicrobial activity against Staphylococcus aureus, as well as the potential to reduce bacterial biofilms and modify the interaction between benzalkonium chloride and the bacterial cell membrane. Overall, the findings demonstrate that the complexation of benzalkonium chloride with β-cyclodextrin and hydroxypropyl-βcyclodextrin represents a promising strategy for the development of nanostructured systems with potential applications in the control of bacterial infections and the improvement of antimicrobial formulations.