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Abstract :
[en] In the last decades, concerns about the hazards of carcinogenic compounds found
in indoor air have risen. Among those compounds, formaldehyde, which is well-known to be found
in paints, tobacco smoke, open fireplaces, insulating foams, lacquers, glues, varnishes, paper and
household products, is of grave concern. With the aim of removing formaldehyde from indoor air,
our work focused on the immobilization of an enzyme (FDH) catalyzing the following reaction in the
presence of NAD+ as an enzyme cofactor: H2CO + H2O + NAD+ + FDH ⇌ HCOOH + H+ + NADH
+ FDH
One of the main challenges in this work was to preserve the activity of an enzyme
immobilized in a harsh environment and to maintain its activity for a long time. Ordered
mesoporous silica and periodic mesoporous organosilicates materials have shown to be good
candidates. They offer a large specific surface area and their physico-chemical properties as well as
their structural properties can be tailored during (or after) their sol-gel syntheses [1,2].
FDH was produced and protein-engineered to have a His-Tag sequence, allowing purification
on a Ni2+ chromatography column. Pure FDH was successfully immobilized on different supports
and its activity was assessed by UV-Vis spectrometry of NADH. The immobilization was
characterized by solid state 29Si NMR and by IR spectroscopy while enzyme loading was
characterized by TG-DSC. The geometrical properties of supports were characterized by Hg
porosimetry, nitrogen adsorption/desorption, TEM (cf. Figure 2) and by small-angle X-ray scattering.
Altogether, these results allowed us to investigate relationships between the activity of immobilized
enzymes and the environment provided by their supports.