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

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 μ M 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. coli for a complex matrix of treatment conditions, including chemical structure and concentration of CCOE/CCPE in treatment systems as well as time and modes of treatments of bacterial cells. The killing efficiency (UV/Vis absorbance and flow cytometry); % growth inhibition (UV/Vis absorbance and colony-forming unit (CFU) assays); surface charge reversal (zeta potential analyzer); and, morphological changes (scanning electron microscopy (SEM), and fluorescence microscopy) of treated bacteria were explored. Such rigorous can greatly clarify our understanding of cell-conjugated molecule binding and growth inhibition mechanism from the viewpoint of fundamental changes bacterial provide informative for and fight against bacteria-organic interactions packaging for food