The sol-gel process occurs even naturally as biomineralization for silica, but also titania and a number of mixed-metal oxides, such as, for example, ilmenite, FeTiO3, as reported in
Bioinorganic Chemistry of Titanium
by Katherine M. Buettner and Ann M. Valentine
Chem. Rev. 2012, 112, 1863
http://pubs.acs.org/doi/abs/10.1021/cr1002886?prevSearch=Buettner&searchHistoryKey
A great number of biomedical applications are exploiting chemically functionalized mesoporous silica. A critical overview of incorporation of chemical functionalities in the framework of mesoporous silica has recently appeared in.
Incorporation of chemical functionalities in the framework of mesoporous silica.
Authored by Rafael Luque, Javier Garcıa-Martınez et al.
Chem. Comm. 2011, 47, 9024
http://pubs.rsc.org/en/content/articlelanding/2011/cc/c1cc11016k