V. SWATHI*, P. RAVISANKAR : Metallic nanoparticles, cancer, drug delivery, specificity, gold nanoparticles 1590-1601 Volume 4, Issue 6 November - December 2013 In the past few decades there has been tremendous enhancement in usage of nanotechnology for formulation of novel drug delivery systems that are intended for diagnosis and treatment of diseases in general and cancer in particular. Cancer is the most wide spread disease throughout the world with millions of new cases every year. Nanotechnology based cancer therapy with minimal side effects and maximum target specificity is on wave, with the main challenge to develop a molecular therapy that circulates in blood undetected by the immune system and recognize the specific target site or organ at which it elicits its therapeutic action. Metallic nanoparticles target cancer cells and cause death of tumor by thermal ablation, hyperthermia etc. The nano size of these metallic nanoparticles also helps in increasing their accessibility towards various compartments of the cells including their nucleus and also cross the blood brain barrier. This potential of nanoparticles to cross the blood brain barrier opens a new way for drug delivery to the brain. The interaction of nanoparticles with various cells, tissues and their toxicity depends upon their composition and chemical nature. Nanoparticles, especially metallic nanoparticles act as versatile agents with a number of bio-medical applications. Hence formulation of metallic nanoparticles brought about a big revolution in both medical and pharmaceutical fields.