A method for producing nanoscale titanium dioxide particles which are
coated with an oxide, a hydroxide or an oxide hydroxide of Al, Ce, Zr
and/or Si wherein the enzymatic precipitant system urease/urea is used.
Said coated titanium dioxide particles can have an average size of less
than 50 nm, the coating providing effective protection against
photocatalytic reactions. The coated particles are suitable, in
particular, as UV absorbers in a transparent organic matrix.