Eco-Friendly Synthesis Methods of Gold Nanoparticles, Their Characterization and Applications in Diagnostic, Therapeutic and Sensors

Nanoparticles have unique traits which make them useful for different purposes. Numerous methods are used to manufacture nanoparticles at commercial scale. Gold nanoparticles (AuNPs) are one of the most utilized and preferred nanoparticles due to their traits like low resistivity, less toxicity, optical, high stability, fluorescence quenching ability, and "surface plasmon resonance". Gold nanoparticles were utilized in ancient Roman Times for staining glasses and till now their new applications are being discovered every day. Various methodologies are utilized for Gold nanoparticle synthesis including conventional chemical methods, UV rays, polymers, ultrasound, plant and microbe-mediated techniques, etc. Conventional techniques are not eco-friendly or cost-effective. Nowadays plants and microbes being cost-effective and eco-friendly are preferred for gold nanoparticle synthesis. Various extracellular, intracellular, and biomolecular techniques are being utilized to manufacture gold nanoparticles. Gold nanoparticles have a vast scope in chemical, biomedicine, food, electronic and forensic industries. AuNPs are widely utilized as sensors, also as carriers in Drug delivery, Photothermal therapy, Heavy metal ion detection etc. This review describes various synthesis techniques, applications, and characterizations of AuNPs.