Rapid time-resolved fluoroimmunoassay for diethylstilbestrol in cow milk samples with a highly luminescent Tb3+ chelate

Water-soluble lanthanide complexes with a helical ligand modified for strong luminescence in a wide pH region

Luminescent helical lanthanide complexes with hydrophilicity were examined for stability and reversibility in a pH region between 1.9 and 11.9.

Ultrasensitive Time-Resolved Fluoroimmunoassay for Saikosaponin a in Chaihu (Bupleuri Radix)

The aim of this study is to establish a time-resolved fluoroimmunoassay (TRFIA) system for quantitative analysis of saikosaponin a (SSa) in the crude drug of Chaihu (Bupleuri Radix). A 96-well microplate coated with rabbit anti-mouse IgG was incubated with the methanol extracts of Chaihu samples and a mouse anti-SSa monoclonal antibody, and a Eu3+-labeled SSa-human serum albumin conjugate was used as the tracer. The established competitive TRFIA showed a good fourth order polynomial fitting from 0.01 to 10.0 μg/mL for standard SSa sample with a detection limit of 0.006 μg/mL. The intra- and inter-assay coefficients of variation of the assay were 7.3% and 8.9%, respectively, and the average SSa recovery was 119.2%. For samples of Chaihu extract, the results of this assay showed a good correlation with those by enzyme-linked immunosorbent assay established previously. This TRFIA system is ultrasensitive for detecting SSa with a wide detection range and a good stability and represents the first attempt of using TRFIA for quality evaluation of the crude drug of Chaihu.

Graphene oxide-modified electrodes for sensitive determination of diethylstilbestrol

This paper reports an electrochemical sensor fabricated with graphene oxide (GO) modified on a chitosan-coated glassy carbon electrode (GO-CS/GCE) and its application for the detection of diethylstilbestrol (DES). It was observed that the effective electrochemical surface area of the GO modified electrode was nearly 10 times that of the bare GCE. This could be used to explain the results that the oxidation peak current of DES on the GO-CS/GCE was much larger than on the bare GCE. Under optimized conditions, the prepared electrode could be used to electrochemically detect DES according to the oxidation of the DES. Based on the technique of differential pulse voltammetry and the accumulation of DES on GO modified electrodes, the calibration curve for DES determination could be obtained with a linear range of 1.5 × 10(-8)-3.0 × 10(-5) M and an estimated detection limit of 3.0 × 10(-9) M (S/N = 3). The feasibility of the developed electrode for tablet sample analysis was investigated. Our investigation revealed that GO could significantly improve the analytical performance of electrochemical sensors.