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Drug delivery by phospholipase A(2) degradable liposomes
J Davidsen1, C Vermehren, S Frokjaer
1Department of Pharmaceutics, The Royal Danish School of Pharmacy, Universitetsparken 2, 2100 Copenhagen, Denmark.
International Journal of Pharmaceutics
|April 3, 2001
Summary
Negatively charged poly(ethylene glycol)-phospholipid (PE-PEG) lipopolymers significantly enhance phospholipase A(2) (PLA(2)) enzymatic activity in liposomes. This suggests improved enzyme binding to polymer-coated, charged lipid nanoparticles.
Area of Science:
- Biochemistry
- Lipid Nanoparticle Technology
- Enzyme Kinetics
Background:
- Liposomes are crucial drug delivery systems.
- Phospholipase A(2) (PLA(2)) is an enzyme that hydrolyzes phospholipids.
- Poly(ethylene glycol)-phospholipid (PE-PEG) polymers are used to modify liposome surfaces.
Purpose of the Study:
- To investigate the impact of PE-PEG lipopolymers on PLA(2) activity.
- To determine how PE-PEG concentration affects liposome properties and enzyme hydrolysis.
- To explore the mechanism behind PLA(2) activity modulation by PE-PEG.
Main Methods:
- Liposomes composed of stearoyl-oleoylphosphatidylcholine (SOPC) were prepared.
- Varying concentrations of negatively charged PE-PEG lipopolymers were incorporated into SOPC liposomes.
- PLA(2) hydrolysis was monitored by measuring the lag-time using fluorescence.
- Zeta-potentials of the liposomes were measured to assess surface charge.
Main Results:
- Increasing PE-PEG concentration led to a significant decrease in PLA(2) lag-time.
- This decrease in lag-time indicates enhanced PLA(2) enzymatic activity.
- Liposomes incorporated with PE-PEG showed altered zeta-potentials, becoming more negatively charged.
Conclusions:
- Negatively charged PE-PEG lipopolymers enhance PLA(2) hydrolysis of SOPC liposomes.
- The enhanced activity may be due to increased PLA(2) binding affinity to the modified liposome surface.
- PE-PEG incorporation offers a method to modulate enzymatic activity on liposome surfaces.