The material particles having dimensions in order of 1-100 nm are called nanoparticles. Many novel electrical, optical, electronic, etc. properties are observed in nanoparticles owing to their high surface activity. The nanoparticles have created the considerable attention from the field of nanotechnology as well as preparation of bio-sensing devices to targeted drug delivery owing to their novel electrical, optical, electronic, etc. properties. The colloidal gold and silver nanoparticles have accomplished extensive importance in therapeutics and diagnostics of treatment of malignant tumours along with cancers, sensing of different biological and chemical elements etc. There are several established physical, chemical and green synthesis methods for preparation of metal (gold and silver) nanoparticles. The nanoparticles become coated with protein due to the property of surface activity, when they are entered/injected into the biological fluid/blood by different ways and formed a protein coated conjugated system is known as “Nanoparticle- Protein corona”.