Gold nanoparticles are widely used in medical diagnostics and treatment due to their unique optical and physical properties. They are employed in imaging techniques, such as in cancer detection, where they enhance contrast in CT scans and other imaging modalities. In therapeutics, they serve as carriers for drug delivery, particularly in targeting cancer cells, minimizing damage to healthy tissues. Additionally, their ability to absorb and convert light into heat is utilized in photothermal therapy to destroy cancer cells.

In the field of electronics, gold nanoparticles are integral in the development of conductive inks and coatings for flexible electronics, such as wearable devices and sensors. Their excellent conductivity and stability make them ideal for creating reliable connections in microelectronic components.

Environmental applications include their use in water purification systems, where they act as catalysts to break down pollutants and harmful chemicals. They are also utilized in sensors for detecting contaminants and toxic substances in the environment.

In biotechnology, gold nanoparticles are used in biosensors for rapid and sensitive detection of biomolecules, such as proteins and DNA, enabling advancements in disease diagnosis and research. Their biocompatibility and ease of functionalization make them valuable tools in various scientific and industrial applications.

Furthermore, gold nanoparticles find applications in cosmetics, where their antioxidant properties and ability to promote skin cell repair enhance the efficacy of skincare products.