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Updated: Jun 19, 2026
Detection and Quantification of Mono-Rhamnolipids and Di-Rhamnolipids Produced by Pseudomonas aeruginosa
Published on: March 29, 2024
Characterization of the interaction between liposomal formulations and Pseudomonas aeruginosa
Yimei Jia1, Hélène Joly, Abdelwahab Omri
1Laurentian University, Sudbury, Ontario, Canada.
Abstract:
The interactions between three liposomal formulations and Pseudomonas aeruginosa cells were evaluated by a lipid mixing assay and electron paramagnetic resonance (EPR) spectroscopy. The effect of the bacteria on the liposomal phase characteristics, the release of the liposomes' content, and the uptake rate of gentamicin by bacteria were monitored as a function of time, using EPR spectroscopy. The [16-DSA uptake](Total) from DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) liposomes reached 93 +/- 12% over a 3-hour assay period, of which 9% crossed the bacterial inner membrane. A small amount of 16-DSA uptake from DPPC/Chol (cholesterol) vesicles was found throughout the 3-hour period of time. Although DPPC/DMPG (dimyristoylphosphatidylglycerol) vesicles showed a smaller value of [16-DSA uptake](Total) with respect to that of DPPC vesicles, they appeared to be effective in disrupting the bacterial membrane, resulting in a greater accumulation of 16-DSA inside the inner membrane. Exposure to bacteria caused the DPPC/Chol, DPPC, and DPPC/DMPG formulations to release 4.6 +/- 1.5, 17.6 +/- 1.2, and 34 +/- 3.7% of their content, respectively. Time-dependent fluid regions were developed within the vesicles when mixed with bacteria, and their growth over time depended on liposomal formulations. Incubation of gentamicin with bacteria for 3 hours resulted in 87 +/- 3% of the drug crossing the bacterial inner membrane. In conclusion, interaction between the liposome drug carriers and the bacterial cells result in vesicle fusion, disruption of the bacterial membrane, release of the liposomal content in the close vicinity of the bacteria cells, and the subsequent intracellular uptake of the released liposomal content.
Insights
Liposomes interact with Pseudomonas aeruginosa, disrupting bacterial membranes and releasing contents. This interaction enhances gentamicin uptake into bacterial cells, improving drug delivery.
Area of Science:
- Biochemistry
- Microbiology
- Materials Science
Background:
- Liposomes are widely investigated as drug delivery systems.
- Pseudomonas aeruginosa is an opportunistic pathogen that poses significant challenges in healthcare settings.
- Understanding liposome-bacteria interactions is crucial for developing effective antimicrobial therapies.
Purpose of the Study:
- To investigate the interactions between different liposomal formulations and Pseudomonas aeruginosa cells.
- To evaluate the impact of these interactions on liposomal integrity, content release, and bacterial drug uptake.
Main Methods:
- Lipid mixing assay and electron paramagnetic resonance (EPR) spectroscopy were employed.
- Monitoring of liposomal phase characteristics, content release, and gentamicin uptake over time.
Main Results:
- DPPC liposomes showed high uptake (93%) and significant content release (17.6%) upon bacterial interaction.
- DPPC/DMPG vesicles effectively disrupted bacterial membranes, leading to greater intracellular accumulation of encapsulated substances.
- Liposome-bacteria interactions facilitated substantial gentamicin (87%) crossing of the bacterial inner membrane.
Conclusions:
- Liposome-bacteria interactions involve vesicle fusion and bacterial membrane disruption.
- These interactions promote the release of liposomal contents near bacterial cells.
- Enhanced intracellular uptake of released contents, including gentamicin, is a key outcome.
