Synthesis of Modified Guanidine-Based Polymers and their Antimicrobial Activities Revealed by AFM and CLSM

Abstract

Modified guanidine-based polymers with chain extension were synthesized by condensation and cross-linking polymerizations in an attempt to increase molecular weight and charge density of the antimicrobial polymers. The antimicrobial activity and the corresponding mechanisms were investigated by several approaches. The results indicated that the antimicrobial activities of the modified guanidine-based polymer, based on the minimum inhibition concentration (MIC) against E.coli, varied with alkyl monomer ratios. UV absorption at 260 nm further quantified the amount of intracellular components leaked into bacteria suspension. The UV absorption measurements were also used to monitor inhibition processes dynamically. It was found that the modified guanidine-based polymer inhibited the growth of bacteria by causing membrane compromised and intracellular leaked. Dual fluorescent dyes were used to stain all bacteria including the dead ones, which enabled us to utilize CLSM to visualize the viability of bacteria in the presence of various modified guanidine-based polymers without causing any damage. The morphologies of bacteria untreated and treated with modified guanidine-based polymer were observed using an atomic force microscope (AFM), which further demonstrated the damage of E.coli membrane and the leakage of intracellular component induced by the modified guanidine-based polymers.

Controlling macromolecular structures towards effective antimicrobial polymers

“…Several biophysical methods are utilized to investigate the membrane disrupting mechanism including the measurement of dye-leakage from dye-filled synthetic liposomes [79,83,182,183], quantification of leaked cellular constituents (e.g. phosphorylated compounds) [14,184], fluorescence-based methods [84], and observation of morphologic changes by scanning electron microscopy [159] [66], transmission electron microscopy [144] and atomic force microscopy [185]. However, all of these methods assist to identify the membrane damaging effects of polymers.…”

Azetidinium Functionalized Polytetrahydrofurans: Antimicrobial Properties in Solution and Application to Prepare Non Leaching Antimicrobial Surfaces

“…To prepare polymer coated antimicrobial surfaces in the current work, we focused on the application of azetidinium functionalized polymers. The advantages of azetidinium groups in this application are: (a) inhibition of bacterial growth via interaction with cell components due to the cationic nature of this group [15,16] and (b) improving the adhesion via both (i) ionic interaction and (ii) covalent linkage. The four membered rings attached to the polymers react with the functional groups on the surface forming covalent bonds [17].…”

Versatile SiO2 Nanoparticles@Polymer Composites with Pragmatic Properties

“…Besides hydrophobicity, RGP, and crystalline features of SNP@PMMA films initiated bacterial cell phospholipids bilayer penetration [28]. Their antimicrobial performance could be attributed to surface hydrophobic interactions and membrane perforation caused by structural interactions amid PMMA and SNP [29].…”