Chitosan-based Maillard products for enzyme immobilization in multilayers structure: Its application in electrochemical sensing

In this work we demonstrate for the first time the advantages of using water-soluble chitosan polycation obtained by Maillard reaction with glucose (G-Chit) or lactose residues for the immobilization of glucose oxidase (GOx) and lactate oxidase by the layer-by-layer adsorption method onto carbon paste electrodes. Besides its solubility in enzyme-compatible media, these polymers have a suitable charge density for electrostatic adsorption and allow adequate charge transfer at the electrode-solution interface. Based on the analysis of the effect of the type of chitosan derivative on the enzymatic response; we built an efficient biosensor based on G-Chit and GOx. The multilayered structure made of three bilayers of G-Chit and GOx showed the best performance; the biosensor exhibits a sensitivity of (12.4 +/- 0.3) mu A mM-1 cm-2 in a glucose concentration range from 180 mu M to 1.75 mM. In addition, the analytical response of this biosensor was tested in milk samples with negligible effects of the matrix. The results confirm the suitability of these chitosan derivatives for the adsorption of enzymes and the construction of supramolecular structures. The favorable environment for the enzymatic activity results in bioelectrodes with fast responses for quantification of glucose even in a complex matrix like milk.

Automated summary

In this study, water-soluble chitosan polycation obtained by Maillard reaction with glucose (G-Chit) or lactose residues was used for the immobilization of glucose oxidase (GOx) and lactate oxidase onto carbon paste electrodes using the layer-by-layer adsorption method. The G-Chit and GOx multilayer structure showed the best performance, with a sensitivity of (12.4 +/- 0.3) mu A mM-1 cm-2 in a glucose concentration range from 180 μM to 1.75 mM. The biosensor exhibited fast responses for quantification of glucose even in milk samples, confirming the suitability of these chitosan derivatives for enzyme adsorption and supramolecular structure construction.