Semiquantitative naked-eye detection of synthetic food colorants using highly-branched pipette tip as an all-in-one device

Colorimetry Combined with Inner Filter Effect-Based Fluorometry: A Versatile and Robust Strategy for Multimode Visualization of Food Dyes

“…The influence of external factors on FDs adsorption was examined, involving system pH, urea (a strongly polar molecule with strong ability to form hydrogen bonds by carbonyl and two primary amino groups) and NaCl concentrations, together with volume fractions of ACN (an organic solvent for disrupting hydrophobic interaction). As shown in Figure S10 in the Supporting Information, the indicator papers-based FDs extraction was greatly disturbed as the alkalinity, as well as NaCl and ACN contents, increased; in the meantime, the colors of FDs-extracted indicator papers bleached gradually, illustrating that electrostatic interaction and hydrophobic effect could be the dominating binding forces for FDs extraction, which agreed well with literature reports. − To completely elucidate the adsorption mechanism, zeta (ζ) potentials of UPTES-derived silica nanoparticles (SiO 2 NPs) with or without extraction of FDs were checked. As seen in Figure , the apparent ζ potentials of bare SiO 2 NPs, BB-, SY-, and AR-adsorbed SiO 2 NPs were, respectively, 18.7 ± 0.60, 0.33 ± 0.08, 5.39 ± 0.25, and 6.17 ± 0.31 mV.…”

“…Differences in structures and properties, including aromatic ring, unsaturated bonds (such as azo group, carbon–carbon/oxygen double bond, etc. ), polarity, and charge effect, have been a significant foundation for the design of separation and detection systems of FDs. − ,, Thanks to their abundant unsaturated structures, strong absorption in ultraviolet–visible light (UV-vis) region is a universal hallmark of FDs. However, the vast majority of FDs have no distinct fluorescence emission, making them excellent candidates to build inner filter effect (IFE)-based detection systems via their absorption toward excitation or emission light of fluorophore while not requiring any direct interaction between them. − Since the IFE-based fluorescence quenching is concentration-dependent, fluorometric and fluorescence detection can be achieved in terms of the mapping relationship between fluorescence signals and FDs concentrations.…”

“…), polarity, and charge effect, have been a significant foundation for the design of separation and detection systems of FDs. [22][23][24][25]27,28 Thanks to their abundant unsaturated structures, strong absorption in ultraviolet−visible light (UV-vis) region is a universal hallmark of FDs. However, the vast majority of FDs have no distinct fluorescence emission, making them excellent candidates to build inner filter effect (IFE)-based detection systems via their absorption toward excitation or emission light of fluorophore while not requiring any direct interaction between them.…”

“…Colorimetry is one of the feasible pathways to accomplish this goal. Ascribing to some distinctive features like simple operation, good portability, and intuitive readout, colorimetric assay has been proven to be a powerful tool for on-site detection in many fields, spanning from medical diagnosis, to environmental monitoring, to food safety. , However, most existing reports on colorimetric analysis were based on single-signal systems, such as indicator papers, − colorimetric pipet tips, fluorometric nanoprobes, etc. Multimodule synergistic visualization, a promising strategy with improved detection accuracy by cross-validation of different detection channels for instrument-free detection, is still very scarce.…”