Stabilization of b-Glucuronidase by Immobilization in Magnetic-Silica Hybrid Supports

b-Glucuronidases are a class of enzymes that catalyze the breakdown of complex carbohydrates.
They have well documented biocatalytic applications in synthesis, therapeutics, and analytics that could
benefit from enzyme immobilization and stabilization. In this work, we have explored a number of
immobilization strategies for Patella vulgata -Glucuronidase that comprised a tailored combination of
biomimetic silica (Si) and magnetic nanoparticles (MNPs). The individual eect of each material on the
enzyme upon immobilization was first tested. Three dierent immobilization strategies for covalent
attachment on MNPs and dierent three catalysts for the deposition of Si particles were tested.
We produced nine dierent immobilized preparations and only two of them presented negligible
activity. All the preparations were in the micro-sized range (from 1299 52 nm to 2101 67 nm
of hydrodynamic diameter). Their values for polydispersity index varied around 0.3, indicating
homogeneous populations of particles with low probability of agglomeration. Storage, thermal,
and operational stability were superior for the enzyme immobilized in the composite material.
At 80 C dierent preparations with Si and MNPs retained 40% of their initial activity after 6 h of
incubation whereas the soluble enzyme lost 90% of its initial activity within 11 min. Integration of
MNPs provided the advantage of reusing the biocatalyst via magnetic separation up to six times with
residual activity. The hybrid material produced herein demonstrated its versatility and robustness as
a support for b-Glucuronidases immobilization.