Functional, Degradable Zwitterionic Polyphosphoesters as Biocompatible Coating Materials for Metal Nanostructures

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Gold nanoparticles (AuNPs) are extensively investigated for molecular imaging, photothermal therapy, and drug delivery.
• Poly(ethylene glycol) (PEG) is a common coating material for AuNPs, but alternatives are sought.
• Developing biocompatible and functionalizable coatings is crucial for nanomaterial applications.

Purpose of the Study:

• To develop and evaluate a zwitterionic polyphosphoester (zPPE) as a novel coating material for gold nanoparticles (AuNPs).
• To assess the stability, biocompatibility, antifouling properties, and immunotoxicity of zPPE-coated AuNPs compared to PEGylated and citrate-coated AuNPs.

Main Methods:

• Synthesis of l-cysteine-functionalized poly(but-3-yn-1-yloxy)-2-oxo-1,3,2-dioxaphospholane (zPBYP) via thiol-yne conjugation.
• Coating of AuNPs with zPPE and characterization using NMR and UV-Vis spectroscopy.
• Evaluation of AuNP stability, degradation, and antifouling properties.
• Assessment of immunotoxicity through cytokine overexpression assays.

Main Results:

• zPPE successfully coated and stabilized AuNPs, despite some minor hydrolysis during purification.
• zPPE coatings demonstrated hydrolytic degradability.
• zPPE-coated AuNPs exhibited superior antifouling properties compared to PEGylated and citrate-coated AuNPs.
• All tested AuNP formulations, including zPPE-coated ones, showed negligible immunotoxicity.

Conclusions:

• Zwitterionic polyphosphoesters (zPPEs) represent a promising alternative to PEG coatings for gold nanoparticles.
• zPPE-coated AuNPs offer excellent antifouling performance and low immunotoxicity.
• The versatile reactive groups on zPPEs allow for tailored nanomaterial preparation for diverse biomedical applications.