The present invention relates to a process for the production of a system comprising providing a porous scaffold comprising functional groups capable of covalently binding MNPs to said porous scaffold; providing at least a population of magnetic nanoparticles (MNPs) comprising functional groups capable of covalently binding the porous scaffold of step a), and contacting the MNPs with the porous scaffold under suitable conditions for the immobilization of the MNPs to the scaffold by means of covalent bonds. The present invention also provides the system obtained by the process, and uses thereof, as well as a method for carrying out an enzymatic reaction.