A smartphone-enabled visual platform for detecting aflatoxins in peanut oil using colorimetric analysis coupled with magnetic imprinted solid-phase extraction.

The study aimed to develop a rapid and sensitive colorimetric platform based on the Emerson reaction to visualize and determine total aflatoxins (AFs) in peanut oil. This method offers the advantage of fast screening for AFs (AFB1, AFB2, AFG1, and AFG2), eliminating the need for specific antibodies. The proposed approach combined colorimetric detection with magnetic dummy imprinted solid-phase extraction and purification, enhancing sensitivity and selectivity. The oxidizer aided the colorless AFs in reacting with 4-aminoantipyrine, producing green condensates. Thus, a dual-mode approach was developed for AFs detection, employing both UV-vis colorimetric and smartphone-based colorimetry. Both methods showed a good linear relationship with the concentration of AFs. Notably, the smartphone-based method demonstrated a detection range of 0.5-57 µg/kg, with a detection limit as low as 0.21 µg/kg. The suggested colorimetric methods present a promising potential for onsite detection and fast screening of AFs in actual samples.

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 (Fe3+) 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 Fe3+ to form a complex, and clearly improved the selectivity of Chi-FITC-4MU for Fe3+ 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 Fe3+ could be realized with excellent selectivity, stability, and anti-interference ability. Based on the unique fluorescence properties of this sensor, the concentration of Fe3+ 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 Fe3+ 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 Fe3+ in actual water.