Loading of curcumin in polyelectrolyte multilayers.

Area of Science:

• Materials Science
• Polymer Chemistry
• Drug Delivery

Background:

• Polyelectrolyte multilayers (PEMs) are versatile thin films built via layer-by-layer assembly.
• Curcumin, a lipophilic compound, is a model drug with potential therapeutic applications.
• Efficient immobilization of lipophilic drugs within a matrix is crucial for drug delivery systems.

Purpose of the Study:

• To investigate the use of polyelectrolyte multilayer (PEM) thin films as a matrix for immobilizing curcumin, a lipophilic model drug.
• To understand the mechanism and factors influencing curcumin loading into PEM films.
• To evaluate the potential of PEMs for lipophilic drug delivery.

Main Methods:

• Fabrication of PEM thin films using layer-by-layer deposition of poly(diallyldimethyl-ammonium chloride) (PDADMAC) and poly(4-styrene sulfonate, sodium salt) (PSS) on quartz slides.
• Loading of curcumin into PEM films by dipping into a curcumin/water/ethanol solution.
• Quantification of curcumin loading using UV-vis spectroscopy.
• Determination of film thickness by controlling the number of PDADMAC/PSS layers.

Main Results:

• Curcumin loading into PEM films was confirmed by a color change and measured via UV-vis spectroscopy.
• The loading mechanism was identified as partitioning, with a partitioning coefficient of 2.07 x 10^5 between the solvent and the PEM film.
• Curcumin loading increased with the number of deposited layers, reaching up to 8 microg/cm^2 in a 20-layer film.
• The extinction coefficient of loaded curcumin was determined to be 64,000 M^-1 cm^-1.

Conclusions:

• PDADMAC/PSS PEM thin films serve as an effective matrix for immobilizing lipophilic curcumin.
• The loading process is driven by partitioning, and higher drug loading is achieved with increased film thickness (more layers).
• These findings highlight the potential of PEMs as a viable platform for the controlled delivery of lipophilic drugs.