Chitosan-organosilane hybrids?Syntheses, characterization, copper adsorption, and enzyme immobilization

Abstract

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.

pH-Sensitive Nitroxide Radicals for Studying Inorganic and Organo-Inorganic Materials and Systems

“…The obtained hybrid materials are used to create sorbents of 3d-metal ions ; to immobilize enzymes (Airoldi & Monteiro, 2000); as a solid phase for the liquid chromatography of organic compounds (Budanova et al, 2001), including enantiomers (Senso et al, 1999); and to improve the mechanical properties of other polymers (Yeh et al, 2007). Other oxides in combination with chitosan allow us to obtain biosensors based on ZnO substrate (Khan et al, 2008), selective sorbents of fluoride ions based on Al2O3 substrate (Viswanathana & Meenakshib, 2010) and magnetic materials based on Fe3O4 substrate (Li et al, 2008).…”

Glutaraldehyde and glyoxal cross-linked chitosan microspheres for controlled delivery of centchroman

“…23 The free amino groups in chitosan contribute toward its solubility in acidic media and reactivity with physical [24][25][26] and chemical cross-linkers. [26][27][28] Glutaraldehyde cross-linked chitosan microspheres have shown dynamic storage properties, 16 ion adsorption, 29,30 and immobilization of enzyme 30 and systems for controlled drug delivery. 31,32 Recently other cross-linkers such as genepin [33][34][35] and glyoxal [36][37][38] and other polymers 37 have been examined for their possible applications in the biomedical field, but few studies are reported in which glyoxal is used as the cross-linker in controlled delivery systems.…”

A relevante potencialidade dos centros básicos nitrogenados disponíveis em polímeros inorgânicos e biopolímeros na remoção catiônica

“…A quitosana modificada com esse anidrido também tem a capacidade de remover azul de metileno, cujo efeito interativo foi termodinamicamente determinado, recentemente 92 . Outros aspectos que elucidam a reatividade da quitosana podem ser constatados quando cruzada com glutaraldeído, o que leva a dispor de grupos aldeídicos livres, que podem interagir com agentes sililantes contendo de um a três átomos de nitrogênio na molécula 125 . No entanto, quando o vidro tem a sua superfície coberta por agentes sililantes, os mesmos interagem com glutaraldeído com subseqüente imobilização da quitosana.…”