Alkyne Nitro Tag Enables Stable and Efficient Protein Functionalization of Gold Nanoparticles

Area of Science:

• Nanomaterials
• Bioconjugation Chemistry
• Surface Chemistry

Background:

• Stable nanoparticle-protein conjugates are crucial for applications in nanomedicine and materials science.
• Conventional surface ligands face challenges like steric hindrance, aggregation, or low conjugation yields.
• Existing methods like physical adsorption or EDC/NHS chemistry have limitations in stability and protein activity retention.

Purpose of the Study:

• To develop a novel, compact heterobifunctional ligand for enhanced nanoparticle-protein conjugation.
• To introduce Alkyne Nitro Tag (ANT) as a design principle for nanoparticle surface modification.
• To demonstrate the efficacy of ANT-functionalized gold nanoparticles (Au@ANT) in creating stable and active bioconjugates.

Main Methods:

• Synthesis and characterization of the Alkyne Nitro Tag (ANT) ligand.
• Functionalization of gold nanoparticles (AuNPs) with ANT to form Au@ANT.
• Conjugation of Au@ANT with model proteins (streptavidin, HRP, IgG) via nucleophilic acyl substitution.
• Evaluation of conjugation efficiency, conjugate stability, and retained protein activity using various assays (lateral flow, Western blotting, enzymatic sensing, immunoprecipitation).

Main Results:

• ANT-capped AuNPs (Au@ANT) demonstrated robust conjugation with multiple proteins.
• Au@ANT conjugates showed significantly higher yields compared to traditional methods.
• Conjugates exhibited improved stability under physiological and denaturing conditions.
• Enhanced retention of protein activity was observed in Au@ANT conjugates.

Conclusions:

• ANT is a versatile and high-performance ligand for generating stable and active nanoparticle-protein conjugates.
• The ANT strategy overcomes limitations of existing methods, offering superior stability and protein activity.
• This approach holds significant promise for advancing nanomedicine and materials science applications.