Scrutinizing the antibacterial activity of poly (1-vinyl-3-alkyl imidazolium) ionic liquids: experimental and computational approach

Background: Antimicrobial resistance has become a serious concern and threat to global health. This has triggered the need for the design of new antimicrobials. In this study, poly-ionic liquid (PIL) homopolymers have been designed by varying the alkyl chain lengths to evaluate their pathogeneses against Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli). Results: The results demonstrated that the antimicrobial and antibiofilm activities depend on the alkyl chain length of PILs (C-10 > C-8 > C-6). To support the experimental findings, in silico analyses were performed to explore the structural and functional information of bacterial RNA polymerase (RNAP) enzymes. A switch region was identified between RNAP beta subunit (RpoB) and RNAP beta' subunit (RpoC) with 1119 amino acids (aa) and 1504 (2-1505) aa, respectively. The docking analysis reflected the docking energies -5.313 kcal mol(-1) for RNAP-poly-1-vinyl-3-hexyl imidazolium complex, -4.634 kcal mol(-1) for RNAP-poly-1-vinyl-3-octyl imidazolium complex, and -3.456 kcal mol(-1) for RNAP-poly-1-vinyl-3-decyl imidazolium complex. Conclusion: The synthesized PIL samples exhibited antibacterial and antibiofilm activities against E. coli and S. aureus. However, the effect on E. coli was more prominent in comparison to S. aureus. The results indicated that both electrostatic interaction and hydrophobic effect played a vital role in enhancing the antibacterial as well as antibiofilm activities. In addition, in silico analysis identified the 'switch region' between RNAP beta subunit (RpoB) and RNAP beta subunit (RpoC). The novel target appeared to be a binding region for PILs and restricted the synthesis of bacterial RNA. It can be concluded that imidazolium-based PILs can be used as safe antibacterial materials in the healthcare sector. (c) 2024 Society of Chemical Industry (SCI).