Transition Metal Methods for Immobilization of Enzymes and Cells

The use of transition metal chemistry for the immobilization of biological molecules is long established and well documented (1 –17 ). This method is based on the chelation properties of transition metals, namely titanium(IV) and zirconium(IV), which seem particularly attractive on account of the nontoxicity of their oxides (2 ). Investigation of a number of gelatinous hydrous metal oxides has shown that hydrous titanium(IV), zirconium(IV), iron(III), vanadium(III), and tin(IV) oxides may be used per se as matrices for immobilization of biocatalyst (3 –5 ). Such hydrous metal oxide materials have proved to be suitable for the immobilization of amino acids (3 ), peptides (3 ), enzymes (1 –3 ), antibiotics (18 ), polysaccharides (19 ), and whole living cells (20 –28 ). The transition metal chelation method has also been used for the immobilization of enzymes and cells onto a variety of inorganic (1 –6 ) and organic (2 ) supports by treatment with a solution of a transition metal salt.