Gold nanoparticles, with their unique optical, electrical, and biocompatibility, exhibit irreplaceable application potential in catalysis, biosensing, and medicine. However, their ultra-small size results in a high specific surface area and surface energy, making them highly susceptible to aggregation through van der Waals forces and electrostatic attraction. This not only leads to the loss of the unique properties of nanomaterials but also severely affects product stability and application effectiveness. Therefore, achieving efficient dispersion and suppressing aggregation of gold nanoparticles has become a core technical challenge for promoting their industrial application.
The aggregation of gold nanoparticles is essentially a spontaneous transformation from a thermodynamically unstable system to a stable state. When the particle size shrinks to the nanoscale, the proportion of surface atoms increases significantly, exposing a large number of unsaturated bonds and charges, which promotes particle attraction and the formation of aggregates. Furthermore, external factors such as solvent evaporation, drying processes, and concentration changes during preparation can also accelerate aggregation.
Once this aggregation forms, it is often irreversible, leading to reduced catalytic activity, decreased sensing sensitivity, and even loss of dispersibility and biocompatibility in biological systems. To address this issue, the industry has developed various dispersion technologies, focusing on surface modification and system regulation to overcome the aggregation problem. Surface modification technology introduces modifiers onto the surface of gold nanoparticles, constructing steric hindrance or electrostatic repulsion layers to block interparticle interactions. Commonly used modifiers include polymers, small molecule ligands, and biomolecules. These substances bind to the particle surface through chemical bonding or physical adsorption, reducing surface energy and forming a steric barrier that effectively prevents particles from agglomerating. For example, in aqueous solutions, introducing charged surfactants can create a uniform electric double layer on the surface of gold nanoparticles, maintaining dispersion stability through the repulsive force of like charges.
System regulation technology, on the other hand, inhibits aggregation through optimizing the preparation and storage environment. During preparation, controlling the reaction temperature, pH value, and reactant concentration can prevent rapid particle growth and aggregation; using solvent systems with excellent dispersibility, such as polyols or water-alcohol mixtures, can reduce the interaction energy between particles; and during storage, low-temperature sealing and light-protection can reduce particle movement and oxidation, maintaining the dispersed state. Furthermore, physical methods such as ultrasonic dispersion and high-pressure homogenization can effectively break down initial agglomerates, providing a foundation for surface modification and system regulation.
Efficient dispersion technology lays the foundation for the expansion of applications for gold nanoparticles. In the field of catalysis, uniformly dispersed gold nanoparticles can provide more active sites, significantly improving catalytic efficiency and selectivity; in biosensing, stably dispersed gold nanoparticles can enhance signal transduction and improve detection sensitivity and accuracy; in the medical field, well-dispersed gold nanoparticles can improve biocompatibility, providing new pathways for drug delivery and imaging diagnostics.
In the future, with the continuous optimization of dispersion technology, the application scenarios of gold nanoparticles will be further expanded, bringing more breakthroughs to materials science, biomedicine, and other fields.
