Interactions between cationic liposomes and bacteria: the physical-chemistry of the bactericidal action

Abstract

The bactericidal effect of dioctadecyldimethylammonium bromide (DODAB), a liposome forming synthetic amphiphile, is further evaluated for Escherichia coli , Salmonella typhimurium , Pseudomonas aeruginosa , and Staphylococcus aureus in order to establish susceptibilities of different bacteria species towards DODAB at a fixed viable bacteria concentration (2.5 ؋ 10 7 viable bacteria/mL). For the four species, susceptibility towards DODAB increases from E. coli to S. aureus in the order above. Typically, cell viability decreases to 5% over 1 h of interaction time at DODAB concentrations equal to 50 and 5 M for E. coli and S. aureus , respectively. At charge neutralization of the bacterial cell, bacteria flocculation by DODAB vesicles is shown to be a diffusion-controlled process. Bacteria flocculation does not yield underestimated counts of colony forming units possibly because dilution procedures done before plating cause deflocculation. The effect of vesicle size on cell viability demonstrates that large vesicles, due to their higher affinity constant for the bacteria (45.20 M ؊ 1 ) relative to the small vesicles (0.14 M ؊ 1 ), kill E. coli at smaller DODAB concentrations. For E. coli and S. aureus , simultaneous determination of cell viability and electrophoretic mobility as a function of DODAB concentration yields a very good correlation between cell surface charge and cell viability. Negatively charged cells are 100% viable whereas positively charged cells do not survive. The results show a clear correlation between simple adsorption of entire vesicles generating a positive charge on the cell surfaces and cell death. -Campanhã, M. T. N., E. M. Mamizuka, and A. M. Carmona-Ribeiro. Interactions between cationic liposomes and bacteria: the physical-chemistry of the bactericidal action.

Antimicrobial Polymer−Based Assemblies: A Review

“…In assemblies with dioctadecyldimethylammonium bromide (DODAB) bilayers, both DODAB and Gr interacted with Escherichia coli and Staphylococcus aureus. Thereby DODAB antimicrobial activity against Gram−negative bacteria [42,43] has been combined with Gr activity against Gram−positive bacteria [67]. This combination broadens the spectrum of antimicrobial activity.…”

“…Several ASA modes of action have been described in the literature, such as leaching of the antibacterial agent from the material [ 39 ], killing upon contact [ 25 , 40 , 41 , 42 , 43 , 44 ], or preventing microbial adhesion [ 22 , 45 , 46 ]. Several ASA−delivered AMPs or APs act by penetrating the cell wall, reaching bacterial cell membranes and causing their disruption [ 25 , 47 ].…”

Nanoparticulate Antibiotic Systems as Antibacterial Agents and Antibiotic Delivery Platforms to Fight Infections

“…The presence of a positive charge provides specific electrostatic interaction with negatively charged molecules such as DNA; therefore, cationic liposomes are one of the most commonly used nonviral gene delivery vectors [171], and also with bacterial cell wall and biofilms, both negatively charged [172][173][174][175]. Moreover, molecules like DODAB and DODAC are quaternary ammonium compounds that form stable vesicles in aqueous solutions with antimicrobial properties since they cause flocculation and death of bacteria [176,177]. Unlike harmless neutral conventional liposomes charged only with antibiotic drugs, cationic vesicles alone are bactericides.…”

“…Unlike harmless neutral conventional liposomes charged only with antibiotic drugs, cationic vesicles alone are bactericides. On one hand, this entails the disadvantage of cytotoxicity towards mammalian cells, while on the other hand, it can suggest a probable synergistic action between the cationic bilayer antimicrobial lipids and antibiotics encapsulated inside [176]. This encouraged the application of cationic liposomes as drug-releasing systems in treating bacterial infections involving natural surfaces such as skin and teeth or biomedical devices.…”

Atividade biológica de uma nova formulação de anfotericina B solubilizada em nanofragmentos catiônicos de bicamada de brometo de dioctadecildimetilamônio

“…IntroáUfão 16 1997). A susceptibilidade das quatro espécies bacterianas ao DODAB foi demonstrada e comparada, através de curvas de viabilidade celular (CAMPANHÃ et al, 1999). Foi estabelecida a relação de troca de carga da superfície celular das bactérias, demonstrando-se que quando essa superfície encontrava-se positiva, as bactérias apresentavam viabilidade em tomo de 0%.…”