Using ratiometric indicator-displacement assays in semi-quantitative colorimetric determination of chloride, bromide, and iodide anions

Abstract

A ratiometric indicator-displacement assay (RIDA) array has been developed for the semi-quantitative colorimetric determination of chloride, bromide, and iodide anions. Determinations of these halide anions follow the displacement reaction using the chelate compound of (2-(3,5-dibromo-2-pyridylazo)-5-(diethylamino)phenol) (3,5-Br2-PADAP) and heavy metal salts as colorimetric reagent. Different from regular silver nitrate titrations, the chloride, bromide, and iodide anions compete with the 3,5-Br2-PADAP ligand and change the colour of the 3,5-Br2-PADAP-metal chelate compound dramatically. These clearer colour changes make the semi-quantitative colorimetric determination of chloride, bromide, and iodide anions possible. The colour changes are imaged using a conventional flatbed scanner, and digitized. After statistical analysis, these colour changes in the RIDA array provide facile identification of chloride, bromide, and iodide anions at a wide concentration range (10 mM to 10 mM) without any misclassification. The RIDA array is able to discriminate without misclassifications among seven concentrations of chloride, bromide, and iodide anions. No shelf life issue exists because the chelating compounds react with halide anions directly without any preimmobilizations.

Ultrastable AgBiS2 Hollow Nanospheres with Cancer Cell-Specific Cytotoxicity for Multimodal Tumor Therapy

“…The leaching Ag + was detected by spectrophotometric determination according to the previously reported techniques. 43,44 The data shown in Figure S5A verified that there was almost no Ag + leakage. Moreover, since Ag + can severely inhibit the growth of bacteria, in vitro antibacterial tests were carried out by the plate coating method to investigate whether there was Ag + leakage.…”

“…Nanostructures with ultrastable structures that retain structural integrity under physiological conditions are of great importance for biomedical applications. , Thus, the leaching of Ag + is an important problem, which may induce systemic toxicity during tumor treatment. The leaching Ag + was detected by spectrophotometric determination according to the previously reported techniques. , The data shown in Figure S5A verified that there was almost no Ag + leakage. Moreover, since Ag + can severely inhibit the growth of bacteria, in vitro antibacterial tests were carried out by the plate coating method to investigate whether there was Ag + leakage. , The normal proliferation of Staphylococcus aureus and Escherichia coli indirectly proved that the as-prepared AgBiS 2 hollow nanospheres exhibited excellent chemical stability (Figure S5B,C).…”

Silver-Mediated Perylene–3, 4, 9, 10–Tetracarboxylate Tetrapotassium Salt Aggregation for Highly Sensitive Detection of Iodide in Water

“…4c shows a linear relationship between fluorescence intensity and [I -] over 1~12.5 µM, with a detection limit (LOD = 3σ/k) of 25.3 nM, which is comparable to, or slightly better, than those of the most sensitive methods hitherto reported for Idetection. [15][16][17] Fig. 4d and Fig.…”

Colorimetric sensing of anions in water using ratiometric indicator-displacement assay

“…Since the concentrations of anions and indicators are low, the precipitation of fine particles formed during the indicatordisplacement process will not affect the imaging much [33]. This is totally different from UV-vis spectrometry, in which a small quantity of residual precipitates may alter UV-vis spectrum completely.…”

“…Based upon this indicator-displacement assay, we recently developed a semi-quantitative determination of halide anions and obtained a facile identification of chloride, bromide, and iodide anions at a wide concentration range [33]. In this paper, we have significantly improved our colorimetric IDA methodology by the combination of array technologies and pattern-recognition methods.…”