Embodiments of the invention are directed to a composition having antimicrobial activity comprising particles comprising at least one inorganic copper salt； and at least one functionalizing agent in contact with the particles, the functionalizing agent stabilizing the particle in a carrier such that an antimicrobially effective amount of ions are released into the environment of a microbe. The average size of the particles ranges from about 1000 nm to about 4 nm. Preferred copper salts include copper iodide, copper bromide and copper chloride. Preferred functionalizing agents include amino acids, thiols, hydrophilic polymers emulsions of hydrophobic polymers and surfactants.
