The fragile nature of most enzymes is a major hindrance to their use in industrial processes. Herein, we describe a synthetic chemical strategy to produce hybrid organic/inorganic nanobiocatalysts; it exploits the self-assembly of silane building blocks at the surface of enzymes to grow an organosilica layer, of controlled thickness, that fully shields the enzyme. Remarkably, the enzyme triggers a rearrangement of this organosilica layer into a significantly soft structure. We demonstrate that this change in stiffness correlates with the biocatalytic turnover rate, and that the organosilica layer shields the enzyme in a soft environment with a markedly enhanced resistance to denaturing stresses.
Silica nanoparticles equipped with an artificial imine reductase display remarkable activity towards cyclic imine- and NAD(+) reduction. The method, based on immobilization and protection of streptavidin on silica nanoparticles, shields the biotinylated metal cofactor against deactivation yielding over 46 000 turnovers in pure samples and 4000 turnovers in crude cellular extracts.
Enzyme shielding at the surface of silica nanoparticles was performed using different mixtures of biomimetic building blocks. The performances of the nanobiocatalysts are strongly impacted by the chemical composition of the shielding layer.
Four new composite materials, formed by silver nanoparticles embedded in polyamino‐cyclodextrin nanosponge architectures, were designed exploiting the affinity of polyamino‐cyclodextrins towards Ag+ ions. These materials were characterized by means of different techniques (thermogravimetry, FT‐IR, solid state NMR, SEM, HR‐TEM), and tested as catalysts for the reduction of nitroarenes and the oxidative coupling of anilines. The results obtained showed synergistic activity between the supramolecular binding abilities of the nanosponge matrix and the catalytic properties of the metal nanoparticle, and open the way towards the design of new composite smart nanomaterials with improved catalytic performances.
The fragile nature of most enzymes is am ajor hindrance to their use in industrial processes.H erein, we describe as ynthetic chemical strategy to produce hybrid organic/inorganic nanobiocatalysts;i te xploits the self-assembly of silane building blocks at the surface of enzymes to grow an organosilica layer,ofcontrolled thickness,that fully shields the enzyme.Remarkably,the enzyme triggers arearrangement of this organosilica layer into asignificantly soft structure.W e demonstrate that this changei ns tiffness correlates with the biocatalytic turnover rate,a nd that the organosilica layer shields the enzyme in as oft environment with am arkedly enhanced resistance to denaturing stresses.
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