Gold nanoparticles are widely used in medical diagnostics due to their unique optical properties. They are employed in biosensors for detecting diseases, where they enhance the sensitivity and accuracy of diagnostic tests. In cancer treatment, these nanoparticles are utilized for targeted drug delivery, ensuring that therapeutic agents are delivered directly to tumor cells, minimizing damage to healthy tissues. Additionally, gold nanoparticles are used in imaging techniques like CT scans and photothermal therapy, where they help in visualizing and destroying cancer cells. In the field of electronics, they are incorporated into conductive inks and coatings, improving the performance of electronic devices. Their catalytic properties also make them valuable in chemical reactions, particularly in environmental applications like water purification and air filtration.