PEG Analogs Synthesized by Ring-Opening Metathesis Polymerization for Reversible Bioconjugation

Area of Science:

• Polymer Chemistry
• Bioconjugation
• Materials Science

Background:

• Poly(ethylene glycols) (PEGs) are crucial in bioconjugation due to their biocompatibility and ability to modify protein properties.
• Existing PEGylation methods often lack controlled synthesis or specific depolymerization capabilities.
• Protein modification is essential for improving drug delivery, diagnostics, and biomaterials.

Purpose of the Study:

• To develop novel unsaturated protein-reactive PEG analogs using ring-opening metathesis polymerization (ROMP).
• To evaluate the biocompatibility and conjugation efficiency of these new polymers.
• To investigate the depolymerization behavior of the resulting protein-polymer conjugates.

Main Methods:

• Synthesis of unsaturated poly(ethylene glycols) (PEGs) with terminal aldehyde functionality via ROMP.
• Conjugation of synthesized rPEGs (6-20 kDa) to hen egg-white lysozyme (Lyz) via amine reactivity.
• In vitro biocompatibility assessment of rPEGs using human dermal fibroblasts (HDFs).
• Analysis of metathesis-based depolymerization of rPEG-lysozyme conjugates.

Main Results:

• Successful synthesis of unsaturated ROMP PEGs (rPEGs) with molecular weights from 6 to 20 kDa.
• Efficient conjugation of rPEGs to lysozyme's free amine groups.
• Demonstrated in vitro biocompatibility of rPEGs, showing no toxicity in HDFs at concentrations up to 1 mg/mL.
• Observed metathesis-based depolymerization of rPEG-lysozyme conjugates, leading to reduced conjugate molecular weight.

Conclusions:

• ROMP provides a viable route for synthesizing unsaturated, protein-reactive PEGs.
• These rPEGs are biocompatible and effectively conjugate to proteins like lysozyme.
• The developed rPEG-protein conjugates exhibit controlled depolymerization, offering potential for stimuli-responsive biomaterials.