Size-dependent flocculation behavior of colloidal Au nanoparticles modified with various biomolecules

Area of Science:

• Nanotechnology
• Materials Science
• Biochemistry

Background:

• Gold nanoparticles (Au NPs) are widely used in biomedical applications.
• Understanding the stability and interactions of Au NPs with biomolecules is crucial for their effective application.
• Biomolecule modification influences the colloidal behavior of nanoparticles.

Purpose of the Study:

• To investigate the flocculation behavior of Au nanoparticles of varying sizes when modified with different biomolecules.
• To elucidate the size-dependent interactions between Au nanoparticles and biomolecules.
• To provide insights into the stabilization mechanisms of modified Au nanoparticles.

Main Methods:

• Synthesis of Au nanoparticles with different sizes.
• Modification of Au nanoparticles with various biomolecules: amino acids (arginine, lysine, cysteine), glutathione (GSH), oligopeptides, and proteins (BSA, HSA, mouse IgG).
• Investigation of flocculation using UV-vis spectrophotometry and transmission electron microscopy (TEM).

Main Results:

• Flocculation behavior varied significantly with both Au nanoparticle size and the type of biomolecule used for modification.
• Small Au nanoparticles showed increased flocculation with amino acid modification compared to larger ones.
• Oligopeptide modification led to flocculation of all tested Au nanoparticle sizes due to extensive hydrogen bonding.
• Protein capping effectively stabilized small Au nanoparticles, with less efficacy for larger ones.

Conclusions:

• The size of Au nanoparticles and the nature of the modifying biomolecule critically influence their flocculation behavior.
• Size-dependent stabilization effects were observed, with proteins offering better stabilization for smaller nanoparticles.
• This study enhances the understanding of biomolecule-nanoparticle interactions, important for designing stable nanomaterials.