A novel sensing platform based on periodate-oxidized chitosan

Abstract

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 × 10⁻⁵ to 1.83 × 10⁻³ M with a detection limit of 4.0 × 10⁻⁶ M.