Time-resolved fluoroimmunoassay of zearalenone in cereals with a europium chelate as label

A competitive indirect time-resolved fluoroimmunoassay(TRFIA) was developed for detection of zearalenone(ZEN) in cereals,in which ZEN conjugated to bovine serum albumin(BSA) is used as solid-phase antigen.A competitive indirect TRFIA was conducted by simultaneously incubating ZEN in standard or extracted samples with anti-ZEN monoclonal antibody over ZEN-BSA coated plates,and then determining the bound ZEN monoclonal antibody with goat anti-mouse europium conjugate.Samples were extracted with methanol/water...

Eu-Chelate Construct Ultrasensitive Time-Resolved Fluoroimmunoassay-Assay of Pepsinogen I

Eu-chelate were used to construct a two-site sandwich-type assay for pepsinogen Ⅰ （PGI） with time-resolved fluoroimmunoassay （TRFIA） as a detection technique. On the noncompetitive assay, captured monoclonal antibodies （McAbs） coated on wells were directed against a specific antigenic site on the PGI. Another McAbs, called as labeling McAbs, were prepared with the Eu-chelate of N-（p-isothiocyanatobenzyl）-diethylenetriamine-N, N, N, N-tetraacetic acid and directed against a different antigenic site on the PGI. The fluorescence counts of bound Eu^3＋ -McAbs were measured with the auto DELFIA1235 system. The PGI in sera from healthy volunteers were determined by PGI-TRFIA. The within-run and between-run CVs of the PGI-TRFIA were 1.9% and 4.7%, respectively, and the recovery rate was 102.65%. The assay had a detection limit of 0.05 μg· L^-1. The PGI-TRFIA provided a linear response from 3.5 to 328 μg· L^-1. The cross-reacting rate with pepsinogen Ⅱ was negligible. The linear correlation of PGI-TRFIA and radioimmunassay measurements resulted in a correlation coefficient of 0.977. The means of healthy volunteers were 154 ±43 μg·L^-1 for serum PGI. The availability of a highly sensitive, reliable, and convenient method for quantifying PGI will allow investigations into the possible diagnostic value of this analyte in various clinical conditions, including gastric carcinoma, duodenal ulcer, gastritis and severe atrophic gastritis.

Simultaneous detection of different serum pepsinogens and its primary application

AIM: To develop the simple, rapid and sensitive dual-label time-resolved fluoroimmunoassay for pepsinogens in human serum.METHODS: Based on two-site sandwich protocol, mono-clonal antibodies (McAbs) against pepsinogen Ⅰ (PG Ⅰ) and PG Ⅱ were co-coated in 96 microtitration wells, and tracer McAbs against PG Ⅰ and PG Ⅱ were labeled with europium (Eu) and samarium (Sm) chelate, respectively. Diluted serum samples of Eu3+- and Sm3+-McAbs were added into microtitration wells simultaneously. After washing, fluorescence of bound Sm3+ and Eu3+ tracers was detected. RESULTS: The detection limit was 0.2 μg/L for PG Ⅰ and 0.05 μg/L for PG Ⅱ. The assay range was 5.0-320.0 μg/Lfor PG Ⅰ and 1.0-55.0 μg/L for PG Ⅱ. The average re-covery rate was 102.7% for PG Ⅰ and 98.8% for PG Ⅱ. Sera from healthy controls and patients with gastric dis-ease were analyzed. The PG detected by dual-label as-say was in good agreement with that detected by single-label assay or by enzyme-linked immunosorbent assay. CONCLUSION: Dual-label assay can provide high-throughput serological screening for gastric diseases.

Use of fluorescent europium chelates as labels for detection of microcystin-LR in Taihu Lake, China

A method using the time-resolved fluorescence technology to establish a highly sensitive microcystin-LR （MC-LR） indirect com- petitive immunoassay was proposed in this work. This method was used to monitor the MC-LR level in source water and treated drinking water from Taihu Lake. Algae in the water samples were removed by eentrifugation, and the MC-LR level was quantified using this method. Testing results showed that the sensitivity of this method was 0.01 μg/L, and the dynamic measuring range was from 0.05 to 2 μg/L. The av- erage recovery was 115%, and the variation （CV） within and between different batches were 7.3% and 9.7%, respectively. Testing results also indicated that this time-resolved fluoroimmunoassay was sensitive and accurate in measuring MC-LR level, especially for quantitative analy- sis MC-LR level in bulk water.

Determination of angiotensin Ⅱ by using europium-labelled streptavidin

There has recently been a great deal of interest in time-resolved fluoroimmunoassay（TRFIA）. Not only the content of proteins, but also the content of haptens canbe detected by TRFIA, e.g. progesterone, digoxin, estrone-3-glucuronide, 17α-hydroxyprogesterone, prostaglandin F2α, etc. We describe here a solid-phase, competitiveTRFIA for angiotensin Ⅱ（AⅡ）. AⅡ is an eight-peptide. It plays an important role