Some microalgae under special conditions (e.g. anaerobic conditions in sulfur-depleted culture medium) possess strong reductive capacity that can be used to reduce metal salts and deposit metals as layers on a substrate surface (polymer). These conditions can be achieved in bioreactors.

By the addition of »metabolic boosters« and/or the selection of special algae strains it is possible to grow the same algae in »toxic« conditions (growth medium with high concentration of metal ions).

With the combination of the above principles it is possible to deposit reduced metals (Pt, Ag, Cu, Al…) on specific surfaces. Depending on the application and desired characteristics of the final product, some surface modification (functionalization) may be needed.