Phosphonium Cationic Borneol Stereochemical Membrane Breaking Arrow: High Antibacterial and Antibiofilm Activity

Bacterial biofilm contamination poses a substantial threat to public health and safety while also leading to considerable economic losses. In this study, a series of both offensive and defensive poly(quaternary phosphonium salt-borneol) copolymers (P(QPx-BOy)), utilizing stereochemically structured borneol as the membrane breaking arrow and quaternary phosphonium salt cations as the electrostatic driving force, were successfully synthesized. Notably, this work exemplifies a novel integration of natural borneol with quaternary phosphonium cations. Subsequently, the molecular structure, molecular weight distribution, microstructure, and corresponding physicochemical properties of the P(QPx-BOy) were characterized using NMR, FT-IR, GPC, SEM, EDS, CA, and DLS. Leveraging the electrostatic interaction between the phosphonium cation and the stereochemical antibacterial mechanism of borneol, P(QPx-BOy) exhibited remarkable antibacterial efficacy against both E. coli and S. aureus, achieving a 100% antibacterial rate with MIC value as low as 30 μg/mL. Furthermore, crystal violet staining assays revealed that borneol’s unique antibiofilm mechanism exerts a significant inhibitory effect on bacterial biofilm formation. Finally, the biocompatibility and antibacterial potential of P(QPx-BOy) were evaluated through cytotoxicity assays and fabric antibacterial tests. Specifically, the integration of borneol essential oil with hydrophilic quaternary phosphonium salt cations effectively addresses the hydrophobic nature of borneol essential oil while mitigating the cytotoxic effects associated with quaternary phosphonium salts. This synergistic combination leverages the strengths of both components, thereby enhancing their suitability for applications in healthcare and public health sectors.