Aerogel Compositions

An anti-fouling additive containing one or more enzymes or proteins as an active ingredient to impede or reduce the evolution of biofilms on structures to be exposed to water, comprising;

• a) a silica based aerogel or cryogel, optionally comprising a metal alcoxide based on Sc, Ti, V, Cr, Mn, Fe, Co, Y, Zr, Nb, Ru, Hf, Ta, W, Re, Si, Al, Ge, In, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu,
• b) one or more enzymes or proteins releasably entrapped in said aerogel or cryogel,
• said aerogel or cryogel being further characterized in having pores of between 1 and 20 nm, and having been manufactured using supercritical extraction, supercritical drying or freeze drying of a corresponding alcogel, the amount of said one or more enzymes or proteins being sufficient to impede or reduce the evolution of biofilms on structures to be exposed to water.

A method for treating a surface of a structure to be exposed to water in order to impede or reduce the evolution of biofilms, comprising mixing from about 95% to about 99.5% by weight of a selected paint base material with from about 0.5% to about 5% by weight of an anti-fouling additive according to claim 3, and applying an adequate amount of said mixture to the surface to be exposed to water to impede or reduce the evolution of biofilms.