Mechanistic Understanding of the Interactions of Cationic Conjugated Oligo- and Polyelectrolytes with Wild-type and Ampicillin-resistant Escherichia coli

Abstract

An in-depth understanding of cell-drug binding modes and action mechanisms can potentially guide the future design of novel drugs and antimicrobial materials and help to combat antibiotic resistance. Light-harvesting π-conjugated molecules have been demonstrated for their antimicrobial effects, but their impact on bacterial outer cell envelope needs to be studied in detail. Here, we synthesized poly(phenylene) based model cationic conjugated oligo- (2QA-CCOE, 4QA-CCOE) and polyelectrolytes (CCPE), and systematically explored their interactions with the outer cell membrane of wild-type and ampicillin (amp)-resistant Gram-negative bacteria, Escherichia coli (E. coli). Incubation of the E. coli cells in CCOE/CCPE solution inhibited the subsequent bacterial growth in LB media. About 99% growth inhibition was achieved if amp-resistant E. coli was treated for ~3–5 min, 1 h and 6 h with 100 μM of CCPE, 4QA-CCOE, and 2QA-CCOE solutions, respectively. Interestingly, these CCPE and CCOEs inhibited the growth of both wild-type and amp-resistant E. coli to a similar extent. A large surface charge reversal of bacteria upon treatment with CCPE suggested the formation of a coating of CCPE on the outer surface of bacteria; while a low reversal of bacterial surface charge suggested intercalation of CCOEs within the lipid bilayer of bacteria.

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“…To further improve the added value of cotton fabrics, many research groups have devoted themselves to creating antibacterial finishing for cotton fabrics [22][23][24]. Among the antibacterial finishing agents, quaternary ammonium salt cationic polymer is a common antibacterial agent [25][26][27]. Mao et al, synthesized ester-containing cationic silicone softeners and coated it on cotton fabric, and found that the cotton fabric obtained good antibacterial activity against both gram-negative and gram-positive bacteria [28].…”

Green synthesis of peptide functionalized reduced graphene oxide (rGO) nano bioconjugate with enhanced antibacterial activity

“…As a matter of fact, surface neutralisation of the bacterial membrane is an important physicochemical parameter governing the antibacterial activity of potential antibacterial conjugates which come directly in contact with the bacterial surface. Previous studies have reported that untreated E. coli exhibits a negative zeta potential usually in the range of −23.0 to −44.0 to mV 42,43 . Whereas, both antimicrobial peptides and rGO, possess a positive zeta potential value, thereby having the capability to neutralize negative charge on E. coli surface and exhibit bactericidal activity 44,45 .…”

Generation of mRNA Vaccine: An Analysis of Two Types of Vectors

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