Film-Forming Aminocellulose Derivatives as Enzyme-Compatible Support Matrices for Biosensor Developments

Abstract

Based on 6(2)-O-tosyl celluloses and 6(2)-O-tosylcellulose derivatives, it has been possible to synthesize a novel soluble aminocellulose type, P-CH2-NH-(X)-NH2 (P=cellulose, (X)=alkylene, aryl, aralkylene or oligoamine) with diamine or oligoamine residues at C6 and solubilizing groups (S) such as acetate, benzoate, carbanilate, methoxy and/or tosylate groups at C2/C3 of the anhydroglucose unit (AGU). Depending on the nature and degree of substitution (DS) of (S), the aminocelluloses are soluble either in DMA and DMSO or in water. They all form transparent films from their solutions. In the case of water-soluble aminocelluloses, for example, an enzyme-specific pH value can be adjusted by protonation of the NH2 end groups at C6. The aminocelluloses apparently form aggregates (on a scale of nanostructures) according to a structure-inherent organization principle. The nanostructures could be imaged on the aminocellulose film surface by atomic force microscopy (AFM) in the form of characteristic topographic structures – as a result of the aggregation of the aminocellulose derivative chains and their interaction with the functionalized film support. In this way, structural and environment-induced factors influencing the nanostructure formation were found. The aminocellulose films can be covalently coupled with biomolecules by bifunctional reaction via NH2-reactive compounds. With the aid of analytically relevant enzymes, e.g. glucose oxidase (GOD), horseradish peroxidase (HRP) and others, it was found that the enzyme parameters can be modified by the interplay of the aminocellulose and coupling structures. A number of new bifunctional enzyme coupling reactions, e.g. via L-ascorbic acid or benzenedisulfonyl chlorides, forming amide or sulfonamide coupling structures led to efficient enzyme activities and long-term stabilities in the case of GOD and HRP coupling to PDA cellulosetosylate films.