Fluorescence Resonance Energy Transfer-Mediated Immunosensor Based on Design and Synthesis of the Substrate of Amp Cephalosporinase for Biosensing

Abstract

The traditional enzyme-linked immunosorbent assay (ELISA) has some disadvantages, such as insufficient sensitivity and low stability of the labeled enzyme, which limit its further applications. In this study, a more stable enzyme, Amp cephalosporinase (AmpC), was selected as the labeled enzyme, and its substrate was designed and synthesized. This substrate contained the cephalosporin ring core as the enzymatic recognition section and the structural motif of the 3-hydroxyflavone (3-HF) as the reporter molecule. AmpC can specifically catalyze the substrate and release 3-HF, which can enter the cavity of β-cyclodextrin (β-CD) on the surface of ZnS quantum dots and form a fluorescence resonance energy transfer (FRET) signal amplification system. An AmpCcatalyzed, FRET-mediated ultrasensitive immunosensor (ACF immunosensor) for procalcitonin (PCT) was developed by combining the signal amplification system of the polystyrene microspheres and effective immune-based magnetic separation. The ACF immunosensor has high sensitivity and specificity for the detection of PCT: its linear range is from 0.1 ng mL −1 to 70 ng mL −1 , and the limit of detection can reach 0.03 ng mL −1 . The spiking recoveries of PCT in human serum samples range from 98.3% to 107%, with relative standard deviations ranging from 2.14% to 12.0%. This approach was applied to detect PCT in real patient serum samples, and the results are consistent with those obtained with a commercial ELISA kit.

Synthesis of 4‐dimethylaminobenzyl chrysin ester‐Zn fluorescent chemical sensor for the determination of Cr(VI) in water

“…[ 15 ] The detection method has the advantages of high sensitivity, low cost, fast response, simple operation, and real‐time detection. [ 16 ] As an important detection method, fluorescent chemical sensors have been widely applied in the fields of biology, [ 17 ] physiology, [ 18 ] pharmacology, [ 19 ] and environmental science. [ 20 ] In recent years, simple fluorescent chemical sensors have been used for rapid and accurate quantitative determination of Cr(VI).…”