Silver nanoparticles are potentially used in different medicinal as well as household products and cosmetics due to their renowned antimicrobial activity. They are also famous for their potential anti-cancer activity but the adverse effects on normal cells are still a serious problem. Herein, to increase the applicability of silver nanoparticles, i.e. lowering the cytotoxicity without altering the potential antimicrobial and anticancer properties, we have developed a novel method of nucleotide metallization via interaction of silver nanoparticles with adenosine triphosphate. These highly stable adenosine triphosphate coated enzyme responsive silver nanoparticles are particularly appealing due to their excellent stability in a normal physiological environment and selective inhibition of human liver carcinoma cells at noncytotoxic doses. The phosphatase driven dephosphorylation of the adenosine triphosphate coated silver nanoparticles can be exploited as a model of cell instructed response. This gives an alternative way for nanomedicines to treat human cancer effectively. Besides the novel anticancer activity, the biocompatible adenosine triphosphate coated silver nanoparticles show excellent bactericidal activity over both Gram positive and Gram negative bacilli.