Simple and selective optical biosensor using Ultrasonicator synthesis of 5-((anthracen-9-ylmethylene) amino)-2,3-dihydrophthalazine-1,4-dione for direct detection of ascorbic acid in vegetables and fruits.

We report an optical biosensor using imine, 5-((anthrcene-9-ylmethylene) amino)-2,3dihydrophthalazine) 1-4-dione (ADD) for direct detection of ascorbic acid (AA) via FRET quenched. The ADD was successfully prepared by using simple ultra - sonication method, which was characterized by various spectroscopic techniques. The fluorescence intensity of ADD probe was drastically quenched in presence of AA, and shown excellent selectivity towards the detection of AA in presence of possible biological active interferences. A wide linear range from 0.25 to 190 µM was achieved towards the detection of AA with a LOD of 10 nM. The occurrence of FRET mechanism is due to intermolecular hydrogen bonding between ADD and AA, which was confirmed by Density Functional Theory calculations. Moreover, the biosensor was successfully applied for the detection of AA in real samples such as fruits and vegetables to demonstrate the practicability. In addition, the developed biosensor could be a simple and economically cheap platform for the detection of AA in food samples.

Designing of New Optical Immunosensors Based on 2-Amino-4-(anthracen-9-yl)-7-hydroxy-4H-chromene-3-carbonitrile for the Detection of Aeromonas hydrophila in the Organs of Oreochromis mossambicus Fingerlings.

A one-pot greener methodology has been adopted for the synthesis of a simple 4H-chromene core-based fluorescent tag of (S)-2-amino-4-(anthracen-9-yl)-7-hydroxy-4H-chromene-3-carbonitrile (AHC), and its structure has been analyzed using NMR spectroscopy. The physicochemical properties of AHC were well-studied by UV-vis and fluorescent spectroscopy techniques. As a result of excellent emitting property (ϕ ≈ 0.75), it has been coupled with anti-AH through amide linkage, and the AHC-tagged anti-AH has been used as an immunoassay for the selective detection of Aeromonas hydrophila in the presence of interfering pathogens. Under optimized conditions, immunosensors could successfully quantify A. hydrophila from 4 to 736 CFU/mL, and the LOD was 2 CFU/mL. Saliently, the immunoassay has been successfully demonstrated for the analysis of A. hydrophila in the organs of Oreochromis mossambicusfingerlings, and results have shown a very good agreement with our optimized neat AH fluorimetric titration results.