The present invention comprises the use of silver-containing nanomaterials that have reduced interaction with light and still mitigate the growth of microorganisms, including fungi. The nanolayer is sufficiently thin and can be non-continuous, so that it has nominal optical effects on the material it is formed on. Silver is combined with other elements to minimize its diffusion and growth into larger sized grains that then would have increased effects on optical properties. Preferably, the additional elements also have mitigation properties for microorganisms, but are not harmful to larger organisms, including humans. Embodiments of the present invention can be used on a wide range of substrates, used in applications such as food processing, food packaging, medical instruments and devices, surgical and health facility surfaces, and other surfaces where it is desirable to mitigate or control the growth of microorganisms.