| abstract |
A compound of formulain which X<sup>1</sup> is a reactive group that can react to form a covalent bond with a reactive group on the surface of a material to be rendered biocompatible, X<sup>2</sup> is a group -O<sup>e</sup> or a precursor of such a group, n is 2, 3 or 4, Y is a group -*NR<sub>3</sub>A<sup>e</sup> wherein each R, which may be the same or different, is a C<sub>1</sub>-C<sub>4</sub> alkyl group and A<sup>e</sup> is an anion present when X<sup>2</sup> is an electrically neutral group or Y iswherein R<sup>1</sup> together with X<sup>2</sup> forms a direct bond between the nitrogen and the phosphorus atoms. |