Reverse thermal gelation of aliphatically modified biodegradable triblock copolymers
Seongbong Jo1, Jin Kim, Sung Wan Kim
1Center for Controlled Chemical Delivery, Department of Pharmaceutics and Pharmaceutical Chemistry, 30 S 2000 E RM 201, University of Utah, Salt Lake City, UT 84112-5820, USA.
Macromolecular Bioscience
|November 14, 2006
Summary
A modified biodegradable polymer forms a gel at body temperature, creating a two-week drug delivery depot in rats. This thermoreversible material shows promise for controlled release applications.
Area of Science:
- Biomaterials Science
- Polymer Chemistry
- Drug Delivery Systems
Background:
- Biodegradable triblock copolymers based on polyethylene glycol (PEG), L-lactide, and epsilon-caprolactone are water-soluble.
- Thermoreversible polymers can undergo sol-to-gel transitions with temperature changes, useful for in situ gelation.
- Developing injectable, biodegradable materials for sustained drug delivery is a significant challenge.
Purpose of the Study:
- To develop a thermoreversible, biodegradable polymer for potential drug delivery applications.
- To investigate the effect of aliphatic modification on polymer properties and thermogelling behavior.
- To evaluate the in vivo performance of the modified polymer as a drug delivery depot.
Main Methods:
- Synthesis of a triblock copolymer from PEG, L-lactide, and epsilon-caprolactone.
- Aliphatic modification of the copolymer to induce thermoreversible properties.
- Characterization of polymer solutions, including sol-to-gel phase transition temperature.
- Subcutaneous injection of polymer solutions into rats to assess depot formation and longevity in vivo.
Main Results:
- A simple aliphatic modification transformed the water-soluble copolymer into a thermoreversible polymer.
- The polymer solution exhibited a sol-to-gel phase transition at mild temperatures.
- Thermogelling behavior was dependent on the degree of aliphatic modification and polymer concentration.
- In vivo subcutaneous injection in rats resulted in immediate depot formation that persisted for two weeks.
Conclusions:
- Aliphatic modification is an effective strategy to create thermoreversible, biodegradable polymers.
- The developed polymer forms stable in vivo depots suitable for sustained drug delivery.
- This thermogelling polymer holds significant potential for advanced drug delivery applications.
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