Simple surface functionalization of polymersomes using non-antibacterial peptide anchors

Area of Science:

• Biomaterials Science
• Nanotechnology
• Protein Engineering

Background:

• Polymersomes, hollow vesicles from block copolymers, are explored for drug delivery, diagnostics, and nanoreactors.
• Surface immobilization of proteins on polymersomes enhances targeting, biosensing, and creates reaction space.
• Existing methods require chemical pre-conjugation of polymers and proteins, which is complex.

Purpose of the Study:

• To investigate a simple and quick method for polymersome surface functionalization.
• To achieve spontaneous insertion of proteins onto preformed polymersomes without chemical pre-conjugation.
• To display enhanced green fluorescent protein (eGFP) on poly(2-methyloxazoline)-poly(dimethylsiloxane)-poly(2-methyloxazoline) (PMOXA-PDMS-PMOXA) polymersomes.

Main Methods:

• Recombinant expression of eGFP-fusion proteins with hydrophobic peptide anchors (cytochrome b5, L protein, VAM3).
• Spontaneous insertion of these fusion proteins into preformed PMOXA-PDMS-PMOXA polymersomes.
• Characterization of insertion efficiency, stability, and protein loading capacity.

Main Results:

• Three out of four designed peptide anchors facilitated spontaneous eGFP-fusion protein insertion into polymersomes.
• Peptide insertion showed linear dependence on protein concentration and was effective across a wide temperature range (4-42 °C).
• High immobilization density achieved (up to 2320 ± 280 eGFP/polymersome) with stable membrane integrity and long-term stability (≥6 weeks).

Conclusions:

• Spontaneous protein functionalization of polymersomes is achievable using peptide anchors.
• This method bypasses the need for polymer pre-conjugation, simplifying the process.
• Mild insertion conditions and stable functionalization open new avenues for polymersome applications.