Surface functionalization of bioactive glasses and hydroxyapatite with polyphenols from organic red grape pomace

An extract of polyphenols was obtained from organic red grape pomace, chemically
analyzed, and used for functionalization of two bioactive glasses and porous hy-
droxyapatite. Functionalization is effective on hydroxyapatite and the bioactive glass
with higher surface reactivity with a different grafting mechanism. Grafting does not
inhibit redox and radical scavenging activity of polyphenols. The grafted polyphenols
make a continuous layer with an almost complete surface coverage. Polyphenols are
released with different kinetics according to the mechanism of grafting and maintain
their redox activity. A homogeneous thin layer of polyphenols is still firmly grafted
on both substrates after 28 days of soaking and it still maintains radical scavenging
activity. The functionalized samples can be sterilized by gamma irradiation.