Durable Anti-Superbug Polymers: Covalent Bonding of Ionic Liquid onto the Polymer Chains

Abstract

Here, we fabricated the ionic liquid (IL) grafted poly(vinylidene fluoride) (PVDF) (PVDF-g-IL) via electron-beam irradiation to fight common bacteria and multidrug-resistant "superbugs". Two types of ILs, 1-vinyl-3-butylimmidazolium chloride (IL (Cl)) and 1-vinyl-3-ethylimidazolium tetrafluoroborate (IL (BF)), were used. It was found that the PVDF-g-IL exhibited superior antibacterial performance, with almost the same mechanical and thermal performance as unmodified PVDF. Nonwovens and films made from PVDF-g-IL materials exhibited broad-spectrum antimicrobial activity against common bacteria and "superbugs" with the strong electrostatic interactions between ILs and microbial cell membranes. With extremely low IL loading (0.05 wt %), the cell reduction of PVDF-g-IL (Cl) nonwovens improved from 0.2 to 4.4 against S. aureus. Moreover, the antibacterial activity of PVDF-g-IL nonwovens was permanent for the covalent bonds between ILs and polymer chains. The work provides a simple strategy to immobilize ionic antibacterial agents onto polymer substrates, which may have great potential applications in healthcare and household applications.

Quaternary Ammonium Compounds (QACs) and Ionic Liquids (ILs) as Biocides: From Simple Antiseptics to Tunable Antimicrobials

“…Composite membranes composed of bacterial cellulose and cholinium poly-ILs with amino acid anions were active against Gram-negative and Gram-positive bacteria and fungi [187]. Poly(vinylidene fluoride) (PVDF) materials grafted with ILs (1-vinyl-3-butylimidazolium chloride, 1-vinyl-3-ethylimidazolium tetrafluoroborate) showed activity against both common bacteria and "superbugs" [188]. Calcium phosphate-IL (1-alkyl-3-methylimidazolium chloride) materials with bactericidal properties were proposed to be used for implants [189].…”

Recent Advances in Ionic Liquids in Biomedicine

“…[ 173 , 174 ] Recently they have been both used alone [ 175 , 176 , 177 , 178 , 179 , 180 , 181 , 182 ] and incorporated into hybrid materials. [ 183 , 184 , 185 , 186 , 187 , 188 , 189 , 190 ] In particular, poly(ionic liquids) have recently shown excellent antibacterial properties [ 191 , 192 , 193 , 194 , 195 , 196 , 197 , 198 , 199 ] and their polymeric character has been used to manufacture antibacterial membranes. [ 200 , 201 ] There are two main proposed mechanisms of action for ionic liquid bactericidal activity.…”

“…[ 183 ] The combination of other materials or techniques, like cyclic main chain polymers made from isosorbide, hexanediol and terephthaloyl chloride, fluorescent diketopyrrolopyrrole, or gamma irradiation during corneal surgery, with ILs have created synergistic antibacterial and antifungal treatments. [ 172 , 190 , 193 ] ILs have also been combined with standard gauze to create antimicrobial wound dressings. However, the mechanism of action of the ionic liquid used in this particular application is unique.…”

“…A majority of the papers reviewed in this section utilize either E. coli , [ 157 , 160 , 161 , 170 , 190 ] Staphylococcus aureus , [ 184 , 192 ] or both [ 153 , 154 , 155 , 156 , 158 , 162 , 165 , 166 , 168 , 169 , 171 , 173 , 174 , 176 , 183 , 184 ] to test IL/formulation bactericidal efficacy. The two bacterial strains are extremely clinically relevant, as these are both common bacterial infections in humans, and they E. coli and S. aureus represent two general categories of bacteria, Gram‐negative and Gram‐positive, respectively.…”

Role of Cationic Side Chains in the Antimicrobial Activity of C18G

“…The rise of antimicrobial resistance not only underscores the need for development of new antimicrobial compounds, but also highlights the necessity to develop new compounds with lower potentials for development of resistance. Many approaches have been taken in the development of new or improved antimicrobials, including combinatorial therapies [ 7 , 8 ], biomolecule mimetics [ 9 , 10 ], natural products [ 11 , 12 ], synthetic polymers [ 13 , 14 ], metals and metal complexes [ 15 ], quorum sensing inhibitors [ 16 , 17 ], and antimicrobial peptides (AMPs) [ 18 ]. AMPs have been an area of extensive study, as they are relatively straightforward to synthesize and characterize, biologically and evolutionarily diverse, and show little evidence of resistance development throughout evolution.…”