Thiol-reactive amphiphilic block copolymer for coating gold nanoparticles with neutral and functionable surfaces

Area of Science:

• Nanomaterials Science
• Polymer Chemistry
• Biomedical Engineering

Background:

• Biomedical nanoparticles often use charged polymers for drug/ligand conjugation.
• Charged surfaces lead to aggregation and non-specific binding in biological environments.
• Neutral, functionalizable surfaces are needed for effective nanomedicine.

Purpose of the Study:

• To develop a novel polymer coating for gold nanoparticles (AuNPs) with a neutral surface.
• To enable direct functionalization of nanoparticles for targeted delivery.
• To improve nanoparticle stability and reduce non-specific binding in physiological conditions.

Main Methods:

• Synthesized a thiol-reactive amphiphilic block copolymer: poly(ethylene oxide)-block-poly(pyridyldisulfide ethylmeth acrylate) (PEO-b-PPDSM).
• Coated gold nanoparticles (AuNPs) with the PEO-b-PPDSM copolymer.
• Characterized the surface charge (zeta potential) and hydrodynamic size of the coated AuNPs.
• Assessed nanoparticle stability and protein adsorption under physiological conditions.

Main Results:

• The PEO-b-PPDSM coated AuNPs exhibited near-neutral surfaces (zeta potential -10 to 0 mV) across a wide pH range (2-12).
• The coated AuNPs demonstrated good stability in various physiological conditions.
• Significantly reduced non-specific adsorption of proteins and biomolecules was observed.
• Nanocomplexes with a hydrodynamic size of ~43.8 nm were achieved.
• Direct functionalization via disulfide-thiol exchange chemistry was demonstrated.

Conclusions:

• The PEO-b-PPDSM copolymer provides a neutral, stable, and functionalizable coating for AuNPs.
• This approach minimizes aggregation and non-specific binding, crucial for nanomedicine.
• The developed nanomaterials show promise for targeted drug delivery and diagnostics.