Trifluoperazine effects on anionic and zwitterionic micelles: a study by small angle X-ray scattering

Area of Science:

• Colloid and Surface Science
• Materials Science
• Biophysical Chemistry

Background:

• Phenothiazine drugs, like trifluoperazine (TFP), are used clinically.
• Surfactant micelles are model systems for drug delivery and membrane studies.
• Understanding drug-micelle interactions is crucial for drug formulation and efficacy.

Purpose of the Study:

• To investigate the structural changes of zwitterionic (HPS) and anionic (SDS) surfactant micelles upon interaction with TFP.
• To determine how TFP concentration and pH affect micelle shape, size, and surface charge.
• To compare TFP's interaction with micelles to that of other phenothiazine drugs.

Main Methods:

• Small Angle X-ray Scattering (SAXS) was employed to study TFP-micelle complexes.
• Data analysis involved modeling of micellar form factors, interference functions, and distance distribution functions.
• Experiments were conducted at various pH values (4.0, 7.0, 9.0) and drug-to-surfactant molar ratios.

Main Results:

• Anionic SDS micelles transformed from prolate ellipsoids to cylinders with increasing TFP concentration, showing growth and surface charge screening.
• Zwitterionic HPS micelles exhibited a slight decrease in size and hydrophobic core radius upon TFP addition.
• At pH 4.0, TFP induced significant micellar growth in SDS micelles without altering the core structure.

Conclusions:

• The axial ratio and shape evolution of surfactant:TFP complexes are dependent on the surfactant's surface charge and the drug:surfactant molar ratio.
• TFP significantly alters micellar structure, with effects varying based on surfactant type and experimental conditions.
• These findings provide insights into the self-assembly behavior of drug-surfactant systems.