Thionine immobilized in crosslinked chitosan films

Abstract

Experimental conditions for the preparation of cross-linked chitosan films embedded with Thionine are described. The main redox and acid-base properties of the immobilized dye are analyzed in terms of results obtained with voltammetry, spectroelectrochemistry and spectrophotometry. An acid dissociation constant for the immobilized dye of 2,7x10-11 was obtained and Thionine retains its redox and acid base activity even when it is immobilized inside the polymer layer. Due to the stable and reversible pH dependent optical signal of the studied film, this membrane can be used as a building component of an optical pH sensor.