A Selective Spectrofluorometric Determination of Micromolar Level of Cyanide in Water Using Naphthoquinone Imidazole Boronic-Based Sensors and a Surfactant Cationic CTAB Micellar System

We developed a new spectrofluorometric method for qualitative and quantitative determination of cyanide in water using the incorporation of naphthoquinone imidazole boronic-based sensors (m -NQB and p -NQB) and a cationic surfactant, certyltrimethyl ammonium bromide (CTAB). This micellar system exhibited great selectivity for cyanide detection with an assistance of the cationic surface of micelle. The interaction of boronic acid of the sensor toward cyanide in CTAB micellar media gave a quantitative measure of cyanide concentration in the micromolar level. Under the optimal condition, fluorescence intensity at 460 nm of m -NQB and p -NQB provided two sets of linear ranges, 0.5–15 μM and 20–40 μM and the limit of cyanide detection of 1.4 μM. Hence, both sensors in CTAB aqueous micellar system offered a considerably promising cyanide detection with 1000–fold enhancement of the detection limit compared to those studied in DMSO: H₂O. The proposed sensors could also be used to determine cyanide in water with good analytical characteristics.     

Highly specific-glucose fluorescence sensing based on boronic anthraquinone derivatives via the GOx enzymatic reaction

The boronic acid anthraquinones, oHAQB and pHAQB, have been designed, and demonstrated to serve as fluorogenic biosensors for glucose. The sensory molecule, oHAQB, has exhibited the specific-glucose sensing via the GOx enzymatic reaction. In this contribution, the fluorescence changes of oHAQB reasonably correspond to the concentration of glucose upon the conversion of boronic acid to hydroxy based sensor by H₂O₂ generated from glucose along with GOx enzymatic reaction. Our sensing ensemble was then successfully applied to determine the glucose concentration in the range of 0.08–0.42 mM. The limit of detection (LOD) of oHAQB for glucose detection using the GOx enzymatic probe is approximately 0.011 mM.