In recent years, composite materials including organic–inorganic systems have drawn special attention due to their enhanced properties such as adsorbents and heterogeneous catalysts. At the same time, large-scale production of environmentally benign functionalized biopolymers, such as chitosan (CS), allows for constantly developing new materials, since CS reveals remarkable properties as a stabilizing agent for metal-containing compounds and enzymes and as an adsorbent of organic molecules. This review is focused on CS-based materials and on the composite systems including CS-oxide and CS-metal composites in particular for application as adsorbents and supports for catalytically active metal nanoparticles and enzymes.

In this short review (Perspective), we identify key features of the performance of biocatalysts developed by the immobilization of enzymes on the supports containing magnetic nanoparticles (NPs), analyzing the scientific literature for the last five years. A clear advantage of magnetic supports is their easy separation due to the magnetic attraction between magnetic NPs and an external magnetic field, facilitating the biocatalyst reuse. This allows for savings of materials and energy in the biocatalytic process. Commonly, magnetic NPs are isolated from enzymes either by polymers, silica, or some other protective layer. However, in those cases when iron oxide NPs are in close proximity to the enzyme, the biocatalyst may display a fascinating behavior, allowing for synergy of the performance due to the enzyme-like properties shown in iron oxides. Another important parameter which is discussed in this review is the magnetic support porosity, especially in hierarchical porous supports. In the case of comparatively large pores, which can freely accommodate enzyme molecules without jeopardizing their conformation, the enzyme surface ordering may create an optimal crowding on the support, enhancing the biocatalytic performance. Other factors such as surface-modifying agents or special enzyme reactor designs can be also influential in the performance of magnetic NP based immobilized enzymes.

Carbon materials are widely used in catalysis as effective catalyst supports. Carbon supports can be produced from coal, organic precursors, biomass, and polymer wastes. Biomass is one of the promising sources used to produce carbon-based materials with a high surface area and a hierarchical structure. In this review, we briefly discuss the methods of biomass-derived carbon supported catalyst preparation and their application in biodiesel production, organic synthesis reactions, and electrocatalysis.

During this work, we studied the possibility of glucose oxidase (GOx) covalent immobilization on a modified inorganic support. A series of GOx-based biocatalysts was synthesized by crosslinking the enzyme to a surface of modified silica or alumina. Polyelectrolyte layers were used as modifiers for the silica and alumina surfaces. These layers promote tight binding of the GOx to the support. The biocatalyst’s activity and stability were studied using an oxidation reaction of d -glucose to d -gluconic acid. It was found that GOx immobilized on the modified SiO ₂ using glutardialdehyde as a crosslinking agent was the most active and stable catalytic system, showing an 85% yield of gluconic acid. A study of the synthesized biocatalyst structure using FTIR spectroscopy showed that the enzyme was covalently crosslinked to the surface of an inorganic support modified with chitosan and glutardialdehyde. In the case of SiO ₂ , the quantity of the immobilized enzyme was higher than in the case of Al ₂ O ₃ .