Protein release from water-swellable poly(D,L-lactide-PEG)-b-poly(ϵ-caprolactone) implants

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Drug Delivery Systems

Background:

• Multiblock copolymers are investigated for biomedical applications.
• Poly(ϵ-caprolactone) [PCL], poly(D,L-lactide) (PDLLA), and poly(ethylene glycol) (PEG) are common biodegradable polymers.
• Controlling copolymer composition influences degradation and drug release.

Purpose of the Study:

• Synthesize and characterize novel water-swellable multiblock copolymers ([PDLLA-PEG]-b-[PCL]).
• Compare the degradation behavior of these new copolymers with previously reported [PCL-PEG]-b-[PCL] copolymers.
• Investigate the release profiles of model proteins from implants made of these copolymers.

Main Methods:

• Synthesis of [PDLLA-PEG]-b-[PCL] multiblock copolymers with varying block ratios.
• Fabrication of polymer implants using hot melt extrusion (HME).
• In vitro degradation studies and protein release assays (lysozyme, bovine serum albumin).

Main Results:

• Degradation rate of [PDLLA-PEG]-b-[PCL] copolymers increased with higher amorphous [PDLLA-PEG] content.
• New copolymers degraded faster than [PCL-PEG]-b-[PCL] copolymers due to PDLLA-PEG block degradation.
• Incomplete protein release observed from [PDLLA-PEG]-b-[PCL] implants, while [PCL-PEG]-b-[PCL] showed sustained release.

Conclusions:

• The degradation rate of [PDLLA-PEG]-b-[PCL] copolymers is tunable by adjusting the block ratio.
• Incomplete protein release from [PDLLA-PEG]-b-[PCL] may be due to protein-degradation product interactions or matrix entrapment.
• Further research is needed to optimize these copolymers for controlled protein delivery applications.