The activation of alcoholic groups of the magnetic
PVAL microspheres was achieved by the reaction with
CDI, a carbonylating agent. It has been proven to be a
suitable agent for the activation of hydroxyl-containing
supports for immobilization technology. The activation
of a support containing hydroxyl groups by CDI and
the subsequent coupling of an enzyme to the support is
presented in Fig. 3. The intermediate activated support
reacts with N-nucleophiles, such as free amino groups in
protein, to give non-basic uncharged N-alkyl carbonate.
Invertase was covalently immobilized via the amino
group to the activated magnetic PVAL microspheres by
the above-explained reaction mechanism. Analysis of
the wash solutions showed that the immobilization
process was irreversible. The enzyme loading and
retained enzyme activity after immobilization on the
magnetic PVAL microspheres were 7.18 mg g1 support,
and 74%, respectively.