Fluorescence and electrochemical integrated dual-signal sensor for the detection of iron ions in water based on an ITO substrate.

A novel type of fluorescent and electrochemical dual-signal sensor was constructed for the sensitive and selective detection of iron ions (Fe) based on a fluorescent material (Chi-FITC-4MU), which was synthesized by combining the organic dye 4-methylumbelliferone (4-MU), chitosan, and fluorescein isothiocyanate (FITC) in a simple step process. The 4-MU could bind to Fe to form a complex, and clearly improved the selectivity of Chi-FITC-4MU for Fe detection. FITC showed excellent fluorescence performance and chitosan was beneficial to the curing of the material. By solidifying the fluorescent material on an ITO surface, the dual-signal detection of Fe could be realized with excellent selectivity, stability, and anti-interference ability. Based on the unique fluorescence properties of this sensor, the concentration of Fe could be visualized in the linear range of 0.1-100 μM based on the degree of fluorescence quenching. Moreover, the highly sensitive and rapid analysis of low concentrations of Fe was achieved through the electrochemical properties of the ITO sensor. The limit of detection (LOD) and the corresponding linear range were 0.0184 nM and 0.1-500 nM, respectively. Furthermore, this dual-signal sensor was effectively used for the detection of Fe in actual water.