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Structural Effect of Rhenium- and Iridium-Complex Liposome Composition on Their Selectivity for Antimicrobial
Giulia Kassab1, Neha Manav2,3, Layla Pires1
1Princess Margaret Cancer Centre University Health Network Toronto M5G 1L7 Canada.
Antimicrobial photodynamic therapy (aPDT) using novel iridium- and rhenium-based liposomes shows promise for treating skin wounds. Optimized liposome structures enhance effectiveness against bacteria while improving safety for host cells.
Area of Science:
- Nanomedicine
- Photochemistry
- Dermatology
Background:
- Antimicrobial photodynamic therapy (aPDT) offers an alternative to antibiotics for chronic skin wound treatment.
- Development of highly selective photosensitizer systems is crucial for improving aPDT efficacy and safety.
- Liposomal formulations provide a platform for delivering photosensitizers and enhancing their properties.
Purpose of the Study:
- To design and evaluate novel rhenium (Re)- and iridium (Ir)-complex-based liposomes as photosensitizers for aPDT.
- To investigate the impact of varying structural components (cholesterol, PEG-lipid, EDTA-lipid, DOTAP) on liposome performance.
- To determine the optimal formulation for enhanced antimicrobial activity and host cell tolerability.
Main Methods:
- Synthesis of Re- and Ir-complex-based phospholipid conjugates for liposome formulation.
- Systematic variation of liposome composition, including cholesterol, PEG-lipid, EDTA-lipid, and DOTAP content.
- Evaluation of photophysical properties, antimicrobial efficacy against *Staphylococcus aureus*, and host cell toxicity.
Main Results:
- Ir/Re-liposomes exhibited enhanced photoactivity compared to monomeric lipids.
- Ir-liposomes showed superior light absorption, emission, and *S. aureus* killing efficacy over Re-liposomes, with better host cell tolerability.
- Optimal formulations with 40% cholesterol and 5% PEG-lipid demonstrated increased potency.
- EDTA-lipid incorporation boosted efficacy but increased toxicity; DOTAP improved bacterial interaction but reduced stability.
Conclusions:
- Structural design of Re- and Ir-complex liposomes is critical for achieving selectivity in aPDT.
- Optimized iridium-based liposomes (Ir-HC) display ideal characteristics for aPDT, balancing effectiveness, selectivity, and stability.
- These findings highlight the potential of tailored liposomal photosensitizers for advanced wound care.
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