Cationic Vesicles as Bactericides (original) (raw)
Related papers
Bacteria Flocculation and Death by Cationic Vesicles
Langmuir, 1995
Dioctadecyldimethylammonium bromide (DODAB) vesicles kill Escherichia coli in the micromolar range of DODAB concentrations. At 1.2 x lo6 bacteridml, the minimum bactericidal concentration is smaller than 0.5 pM DODAB for an interaction time of 24 h. DODAB effects on the cells are described using microelectrophoresis, viable counts and turbidimetry over a range of bacterial number densities, and DODAB concentrations. Electrophoretic mobility for the cells as a function of DODAB concentration establishes the DODAB amount required to attain charge neutralization on the cell surface and maximal flocculation rate and extent. From los bacteridml, there is rapid bacteria flocculation induced by DODAB.
Analysis of the Bacterial Vesicles' Enhanced Toxicological Threat Via Electron Microscopy
Advancing Medicine through Nanotechnology and Nanomechanics Applications
This study shows the importance of electron microscopy in the analysis of the interaction of microorganisms (Staphylococcus aureus) with polymeric (polyurethane) dental prostheses. Starting from the biofilm formation and the biodestruction of the plastic material resulting in the production of polyurethane nanoparticles, the focus is on the bacterial secretion of membrane vesicles (in the range of 20-50 nm) loaded with plastic nanoparticles (from 2-3 to 10 nm) and on the toxicological threat that these delivery devices represent when interacting with host cells. The nanoparticles deliverance led by the bacterial infections dynamics opens new ways to the possibility of delivering drugs to selected cells.
Interactions between Cationic Vesicles and Cultured Mammalian Cells
Langmuir, 1997
The interaction of small cationic vesicles composed of dioctadecyldimethylammonium bromide (DODAB) with normal versus transformed mouse fibroblasts is described using cell microelectrophoresis, turbidimetry, and cell viability assays over a wide range of DODAB concentrations (10-7-10-3 M). Normal and transformed cells (10 4 cells/mL) attain a point of zero charge at, respectively, 18.0 and 1.6 µM DODAB. Further increasing DODAB concentration (C) generates positively charged cells. At 10 5 cells/mL and C g 50 µM, DODAB induces cell-cell adhesion. For transformed and normal cells, peak adhesion occurs at 100 and 1000 µM DODAB, respectively. Upon 0.5 h interaction time with 100 µM DODAB, at 10 4 cells/mL, 20% of cell death is obtained for normal cells whereas transformed cells remain unaffected. Transformed cells have a higher affinity for DODAB vesicles than their normal counterparts but are more resistant to DODAB-induced cell death. The results indicate that DODAB vesicles interact with cells with very high affinity at low ionic strength and are not toxic below 1 mM, suggesting that they might successfully deliver oppositely charged proteins or DNA strands to cells. These results may be of importance for liposome-mediated processes currently being used for drug or gene delivery to cells.
Size, Electrophoretic Mobility, and Ion Dissociation of Vesicles Prepared with Synthetic Amphiphiles
Journal of Physical Chemistry, 1990
Vesicles prepared with synthetic amphiphiles (dioctadecyldimethylammonium bromide and chloride, dihexadecyl phosphate and its sodium salt) were obtained by sonication, ethanol injections, and chloroform injections. The hydrodynamic diameter of vesicles (Dh), estimated from the diffusivity measured by quasielastic light scattering, ranged from 230 to 3000 A. The electrophoretic mobility (U,) was measured by free-flow electrophoresis. The zeta potential (l) and the degree of counterion dissociation (a) of the vesicles were calculated from U, and conductivity data. a decreased with increasing Dh of the vesicles, probably due to the decreasing headgroup area and the increasing counterion association needed to relax the surface electrostatic potential. The electrophoretic mobility was also calculated (U,) according to an impenetrable, nonconducting sphere model with a spherically symmetric charge distribution approximation. Within the limits of the experimental error(s) of the (different) methods employed and the assumptions made in the calculations, the fact that the UJU, ratio ranged from 1.3 to 7.5 was considered to be a good agreement between the calculated and the experimental values.
Colloids and Surfaces B: Biointerfaces, 2009
The design of efficient liposomal systems for drug delivery is of considerable biomedical interest. In this context, vesicles prepared from cationic/anionic surfactants may offer several advantages, mainly due to their spontaneity in formation and long-term stability. There is also an impending need to produce less toxic, more biocompatible amphiphiles, while maintaining the desirable aggregation properties. In this work, we present data for acute toxicity to Daphnia magna (IC 50 ), and potential ocular irritation (HC 50 ) for some newly prepared ionic surfactants with dodecyl chains, derived from the amino acids tyrosine (Tyr), serine (Ser), hydroxyproline (Hyp) and lysine (Lys). The micellization behavior of the compounds, evaluated from surface tension measurements, is presented and compared to more conventional ionic amphiphiles. Two types of spontaneouly formed catanionic vesicles, composed either by a dodecyltrimethylammonium bromide (DTAB)/Lys-derivative and or Ser-/Lys-derivative mixture, have also been tested for their ecotoxicity and hemolytic potential. All the micelle-forming surfactants as well as the vesicle-containing mixtures are found to have lower ecotoxicity than the reference surfactant DTAB. Moreover, the results from hemolysis and hemoglobin denaturation tests show that the Tyr-and Lys-derivatives are moderately irritant, whereas the Hyp-and Ser-ones are just slightly irritant. Even more significantly, the vesicle-containing mixtures exhibit lower hemolytic activity than the neat surfactants, a positive result for their potential use in liposomal formulations.
Journal of Bacteriology, 1996
Pseudomonas aeruginosa releases membrane vesicles (MVs) filled with periplasmic components during normal growth, and the quantity of these vesicles can be increased by brief exposure to gentamicin. Natural and gentamicin-induced membrane vesicles (n-MVs and g-MVs, respectively) are subtly different from one another, but both contain several important virulence factors, including hydrolytic enzyme factors (J. L. Kadurugamuwa and T. J. Beveridge, J. Bacteriol. 177:3998-4008, 1995). Peptidoglycan hydrolases (autolysins) were detected in both MV types, especially a periplasmic 26-kDa autolysin whose expression has been related to growth phase (Z. Li, A. J. Clarke, and T. J. Beveridge, J. Bacteriol. 178:2479-2488, 1996). g-MVs possessed slightly higher autolysin activity and, at the same time, small quantities of gentamicin. Both MV types hydrolyzed isolated gram-positive and gram-negative murein sacculi and were also capable of hydrolyzing several glycyl peptides. Because the MVs were b...
Vesicles as antibiotic carrier: State of art
International Journal of Pharmaceutics, 2020
Antimicrobial resistance (AMR) has become a global health problem. Bacteria are able to adapt to different environments, with the presence or absence of a host, forming colonies and biofilms. In fact, biofilm formation confers chemical protection to the microbial cells, thus making most of the conventional antibiotics ineffective. Prevention and destruction of biofilms is a challenging task that should be addressed by a multidisciplinary approach from different research fields. One of the medical strategies used against biofilms is the therapy with drug delivery systems. Lipidic nanovesicles are a good choice for encapsulating drugs, increasing their pharmacodynamics and reducing side effects. These soft nanovesicles have many advantages for their compositions similar to the cell membrane, physical and chemistry properties, good affinity with drugs and easy route of administration. This review summarizes the current knowledge on different types of vesicles which may be used as antibiotic carriers. The main preparation and purification methods for the synthesis of these vesicles are also presented. The advantages of drug encapsulation are critically reviewed. In addition, recent works on endolysin formulations as novel, "greener" and efficient antibiofilm solution are included. This paper can provide useful background for the design of novel efficient formulations and synergistic nanomaterials and could be also useful at the pharmaceutical industry to develop wastewater treatments and reduce the antibiotics in the environmental waters.
Peptides, 2010
We have designed and synthesized a series of cationic ␣-helical AMPs with improved antibacterial activity and selectivity against a broad spectrum of G(+) and G(−) bacteria. In the current study, we intended to gain further insight into the mechanisms of action between AMPs and cellular membranes using model liposomes of various phospholipid compositions. Circular dichroism measurements showed that AMPs adopted amphipathic ␣-helical conformation in the presence of negatively charged vesicles (DOPC/DOPG = 1:3), while they were largely unstructured when incubated with neutral vesicles (DOPC). The interaction of AMPs with phospholipid vesicles were further analyzed by calcein leakage experiments. AMPs exhibited weak dye-leakage activity for DOPC (neutral) vesicles, while they effectively induced calcein leakage when interacted with DOPC/DOPG-entrapped vesicles. These results indicated that our newly designed cationic AMPs did show preferences for bacteria-mimicking anionic membranes. All of them exert their cytolytic activity by folding into an amphipathic helix upon selectively binding and insertion into the target membrane, leading to breakdown of the membrane structure, thus causing leakage of cell contents, resulting finally in cell death. Elucidating the mechanism of the membranolytic activity of AMPs may facilitate the development of more effective antimicrobial agents.
Langmuir, 2013
Phospholipid vesicles have been the focus of attention as potential vehicles for drug delivery, as they are biomimetic, easy to produce, and contain an aqueous compartment which can be used to carry hydrophilic material, such as drugs or dyes. Lipid vesicles used for this purpose present a particular challenge, as they are not especially stable and can rapidly break down and release their contents away from the target area, especially at physiological temperatures/ environments. This study aims to investigate optimum methods for vesicle stabilization where the vesicles are employed as part of a system or technology that signals the presence of pathogenic bacteria via the effect of secreted cytolytic virulence factors on a sensor interface. 1 A number of approaches have been investigated and are presented here as a systematic study of the long-term (14 day) stability at 37°C, and at various pHs. The response of vesicles, both in suspension and within hydrogels, to Staphylococcus aureus (RN 4282) and Pseudomonas aeruginosa (PAO1) whole bacteria, and supernatants from overnight cultures of both (containing secreted proteins but free of cells), was measured via a sensitive encapsulated carboxyfluorescein release assay. The results showed that lipid chain length, cholesterol concentration, and stabilization via photopolymer stable components were critical in achieving stability. Finally, dispersion of the optimum vesicle formulation in hydrogel matrixes was investigated, culminating in the in vivo demonstration of a simple prototype wound dressing.
Bacterial membrane vesicles (MVs) facilitate long-distance delivery of virulence factors crucial for pathogenicity. The entry and trafficking mechanisms of virulence factors inside host cells is recently emerging, however, if bacterial MVs modulate the physicochemical properties of the host lipid membrane remains unknown. Here we quantitatively show that bacterial MV interaction increases the fluidity, dipole potential and elasticity of a biologically relevant multi-component host model membrane. The presence of lipids containing head-groups such as phosphatidylcholine, phosphatidylglycerol and phosphatidylinositol and a moderate acyl chain length of C16 helps the MV interaction. While significant binding of bacterial MVs to the raft-like lipid membranes with phase separated regions of the membrane was observed, however, the elevated levels of cholesterol tend to hinder the interaction of bacterial MVs. We further quantify the change in excess Gibbs free energy of mixing of bacteria...