Drug release from a pH-sensitive multiblock co-polymer thermogel

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Polymer Chemistry

Background:

• Developing advanced drug delivery systems is crucial for improving therapeutic efficacy and patient compliance.
• pH-sensitive polymers offer tunable release profiles based on physiological conditions.
• Multiblock co-polymer thermogels present a promising platform for encapsulating and releasing diverse therapeutic agents.

Purpose of the Study:

• To investigate the potential of a Pluronic(®)-based pH-sensitive multiblock co-polymer thermogel for sustained release of therapeutic agents.
• To characterize the loading and release kinetics of both hydrophobic small-molecule drugs and hydrophilic macromolecules from the thermogel.
• To evaluate the influence of pH and molecular weight on drug release profiles.

Main Methods:

• Synthesis and characterization of a Pluronic(®)-based pH-sensitive multiblock co-polymer thermogel.
• Loading of hydrophobic drugs (paclitaxel, camptothecin) and hydrophilic macromolecules (fluorescein-labeled dextrans) into the thermogel.
• Assessment of gelation behavior, micelle size, and drug loading efficiency.
• In vitro release studies at different pH values (5.0, 6.5, and neutral pH) and evaluation of release mechanisms (diffusion and erosion).

Main Results:

• The multiblock co-polymer thermogel successfully loaded hydrophobic drugs and hydrophilic macromolecules, significantly enhancing drug solubility.
• Drug loading increased micelle size from 20 to 100 nm.
• The thermogel exhibited pH-dependent drug release, with faster release at lower pH.
• Sustained release of hydrophobic drugs was observed up to 40 days at neutral pH.
• Hydrophilic dextran release was dependent on molecular mass, with a 40 kDa threshold for sustained release, indicating suitability for large molecules like enzymes and antibodies.

Conclusions:

• The Pluronic(®)-based pH-sensitive multiblock co-polymer thermogel is a versatile platform for controlled drug delivery.
• The system demonstrates sustained release capabilities for both lipophilic and hydrophilic molecules.
• The pH-sensitive and molecular weight-dependent release mechanisms highlight its potential for targeted and long-term therapeutic applications.