Anticancer activities of silver ions in cancer and tumor cells and DNA damages by Ag+ - DNA base-pairs reactions

Silver has long been known to have antimicrobial properties and were used until chemical antibiotics came into vogue. Metallic silver and most inorganic silver compounds ionize in moisture, body fluids and secretions to release biologically active Ag+, which the silver ions have been used for the characteristics of toxicology and pharmacology as antimicrobial agent.1 Nanosilver particles have been widely used in a range of biomedical application, including diagnosis, treatment, drug delivery, medical device coating, and for personal health care. Due to recent advances in nanotechnology, it is now possible to produce silver at nanoscale. In addition to their potential electronic and transparent conductor applications, the emergence of nanosilver materials in antimicrobial consumer goods and medical products is driving the growth of the nanosilver market.2 Among the different nanosilver preparation, silver nanoparticles(AgNPs) can be synthesized in a variety of ways, each with its own advantages and disadvantages. The most common methods of AgNPs synthesis are through chemical reduction of silver salt (AgNO3) using a reducing agent (sodium borohydride).2 During chemical reduction, silver ion Ag+ receives an electron from the reducing agent and reverts to its metallic form Ag0 eventually clustering to form AgNPs. AgNPs are cytotoxic to cancer cells and possess excellent potential as an antitumor agent, in which AgNPs induce cytotoxicity, generate reactive oxygen species (ROS), and cause mitochondrial damage to human cells. Toxic effects indifferent cell types depend on the interactions and distribution patterns of the nanoparticles.3 The size of nanoparticles influences the binding and activation of membrane receptors and subsequent protein expression in cancer cells.3 AgNPs of 12 nm size caused chromosomal aberration and DNA damage, and induced proliferation arrest in cell lines of zebrafish indicating that AgNPs must be investigated for their potential teratogenic effects in humans.4 AgNPs have applications in many industries including biomedicine, pharmaceuticals, biotechnology, nanomedicine, and instrumentation as antibacterial agents, drug delivery agents, biosensors, and environmental sensors due to their unique properties. In this review, firstly antibacterial activities and the bactericide mechanisms of Ag+ ion solution were investigated, in which antibacterial mechanisms for the actions of Ag+ ion solution by bacteriolyses and destructions of bacterial cell walls were clarified. Secondly, the anti-cancer activities of silver nanoparticles (AgNPs) are generally investigated, in which the interactions of anticancer activity of silver (I) ions