Designed aliphatic aminocellulose derivatives as transparent and functionalized coatings for enzyme immobilization

The introduction of aliphatic diamine residues into cellulose was realized starting from 6-O-tosylcelluloses containing carbanilate, benzoate, and methoxy groups at the C2/C3 position of the anhydroglucose units (AGU). By nucleophilic substitution reactions of the tosylate groups with alkylene diamines [ADA, H2N- (CH2)(n)-NH2, n = 2, 4, 6, 8, 12] and monofunctionalization of the ADA it was possible to obtain soluble and film-forming 6-deoxy-6-(omega-aminoalkyl)aminocellulose esters and ethers 1-14. 1,2-Ethylene and 1,4-butylene diamine (EDA and BDA) cellulose carbanilates (1, 2) with a degree of substitution (DS) of the diamino residues of less than 0.4 are soluble in N,N-dimethy- lacetamide (DMA) and dimethylsulfoxide (DMSO), even 6 months after preparation. The 2,3-di-O-methyl-6-ADA-celluloses are soluble in many different solvents, including water, ethanol, and DMSO. All derivatives form transparent films from their solutions. These films are very smooth and exhibit a roughness of less than 0.5 nm, determined using atomic force microscopy (AFM). Owing to the introduced primary amino groups, the films are well suited for enzyme immobilization. For instance, glucose oxidase (GOD) could be immobilized onto a film of BDA cellulose carbanilate (DSBDA = 0.49, DScarbanilate = 1.50, DStosylate = 0.20) with an activity of 0.2 U/cm(2) using benzoquinone as the immobilization reagent.