A novel sensing platform based on periodate-oxidized chitosan

A novel thionine (TH) sensing platform was proposed based on immobilization of TH on a periodate-oxidized chitosan (CS) modified glassy carbon electrode (GCE) surface. Oxidation of CS by periodate can lead to the cleavage of carbon-carbon bonds on the pyranosidic ring of CS, with the generation of dialdehyde groups. TH, an electroactive mediator, was selected as a model of amine compounds to react with the aldehyde group via Schiff-base reaction. Due to the resulting aldehyde-enriched surface and covalent immobilization of TH on periodate-oxidized CS, the CS-grafted-TH showed a pronounced electrochemical response with high stability. The application of the fabricated TH sensing platform as a hydrogen peroxide (H2O2) sensor was also investigated and it exhibited a rapid response to H2O2 within 4 s. The linear calibration ranged from 1.0 x 10(-5) to 1.83 x 10(-3) M with a detection limit of 4.0 x 10(-6) M.