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New organic-inorganic hybrids SiGCX (X ϭ 1 to 3) were prepared from the biopolymer chitosan with a degree of the deacetylation of 86% and three distinct silylating agents of the type (. Both chitosan and silylating agents have the amine groups crosslinking through linear glutaraldehyde units. Two stages were proposed for this synthetic method: crosslinking, and sol-gel processes. The resulting dried hydrogels are amorphous, insoluble in organic as well as acidic or alkaline aqueous media, and exhibited a lamellae-like surface morphology. The hybrids SiGCX (X ϭ 2 and 3) have a larger adsorption capacity for copper ion than natural chitosan, with very similar kinetics of adsorption, defining a plateau after 1 h. The adsorption of copper increases with the organic chain length of the silylating agents: [(1.72 Ϯ 0.05); (1.98 Ϯ 0.06) and (2.49 Ϯ 0.07)] ϫ 10 Ϫ2 mmol/g for SiGCX (X ϭ 1 to 3), respectively, and chitosan adsorbed (1.72 Ϯ 0.05) ϫ 10 Ϫ2 mmol/g. These hybrids presented a good capacity for immobilizing enzymes, which decreased with the increase of the organic chain length of the silylating agents, that is, from SiGC3 to SiGC1. The amount of catalase immobilized for the hybrids SIGCX (X ϭ 1 to 3) is 29.03 Ϯ 0.87; 25.79 Ϯ 0.77, and 17.94 Ϯ 0.54 mg g Ϫ1 , respectively, which is larger than the value of 12.21 Ϯ 0.37 mg g Ϫ1 obtained for chitosan.

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