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A one-pot greener methodology has been adopted for the synthesis of a simple 4 H -chromene core-based fluorescent tag of ( S )-2-amino-4-(anthracen-9-yl)-7-hydroxy-4 H -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 mossambicus fingerlings, and results have shown a very good agreement with our optimized neat AH fluorimetric titration results.

Simple, ultrasensitive and selective diagnostic tool is required for the quantification of creatinine in human biofluids. To the best of our knowledge, we are reporting the second fluorescent as well as colorimetric biosensor for creatinine with a very good linear range. We have utilized a simple water soluble Rhodamine B dye as a probe because of its excellent emitting properties and quantum yield. As a colorimetric biosensor, the dye has selectively detected the Au3+ ions in a ratiometric aspect through ICT mechanism among all other interfering metal ions. When the creatinine was introduced, the Au3+ ions were gradually released from the dye and binded with the creatinine which finally enhanced the fluorescent intensity. The Stern Volmer quenching constant Ksv was found to be 2.6 x 109 M−1. As a colorimetric biosensor, the limit of detection and linear range for creatinine are found to be 54 nM and 100 nM to 15 μM, respectively. Under the optimized condition, the fluorescent biosensor has detected the creatinine within the linear range of 10 nM to 1.2X10−3M along with the LOD of 5 nM. The linear range of developed biosensor implies that the biosensor can be applied for clinical diagnosis of muscle disorder (creatinine level < 40μM), extreme renal problem (creatinine level=1000μM). We have extended the application of this developed biosensor for the determination of creatinine in human urine sample and achieved a very good recovery.Introduction

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In this work, a novel optical immunoassay platform using(S)-2-amino-4-(4-formylphenyl)-4H-chromene-3-carbonitrile as an optical probe which was synthesized by an ultra-sonication method. The structure of the probe was elucidated by Fourier-transform infrared...