Enhancing PEDOT modified electrode for tartrazine sensing through the immobilization of MIL-100(Fe) metal-organic framework

Background: Conductive poly(3,4-ethylenedioxythiophene) or PEDOT emerges as an ideal mediator in fabricating electrochemical sensors. Concurrently, porous metal-organic frameworks (MOFs) present intriguing characteristics such as sufficient surface area, stable structures, and alterable surface ligands. The combination of these two materials in fabricating sensors has started to gain significant attention. Methods: We investigated the effectiveness of employing Fe-based MOF or MIL-100(Fe) in conjunction with a PEDOT-modified Pt electrode for detecting the synthetic azo dye tartrazine, which is commonly used in food coloring. Our investigation encompassed two distinct approaches. Initially, we immobilized MIL-100(Fe) to the PEDOT/Pt electrode during the electrochemical synthesis of the PEDOT film. Subsequently, we pursued the attachment of MIL-100(Fe) onto the surface of the synthesized PEDOT film by applying positive or negative potentials. Significant Findings: We have achieved favorable lower reductive potentials, competitive sensitivities, remarkable repeatability and stability for all MIL-100(Fe)/PEDOT/Pt electrodes. Interestingly, we observed the transformation of MIL-100(Fe) into a flower-like structure under -1 V potential while immobilizing on PEDOT/Pt. This structural alteration led to an approximately twofold amplification in sensitivity for tartrazine detection, reaching 1.818 mu A/mu M. These findings clearly indicate the potential synergies between MIL-100(Fe) and PEDOT for the fabrication of electrochemical sensors.