Dual-cardiac marker capillary waveguide fluoroimmunosensor based on tyramide signal amplification.

The early diagnosis of acute myocardial infarction requires the determination of several markers in serum shortly after its incidence. The markers most widely employed are the isoenzyme MB of creatine kinase (CK-MB) and the cardiac troponin I (cTnI). In the present work, a capillary waveguide fluoroimmunosensor for fast and highly sensitive simultaneous determination of these markers in serum samples is demonstrated.

Bulk fluorescence light blockers to improve homogeneous detection in capillary-waveguide fluoroimmunosensors.

A simple approach that employs black drawing ink (BDI) as bulk fluorescence light blocker and improves considerably the homogeneous signal detection in capillary-waveguide fluoroimmunosensors is presented. The concept was proved using a capillary sensor configuration. Fluorescent molecules in the capillary were excited by a laser beam vertically to its axis and the emitted photons that were trapped and waveguided through the capillary wall were then collected.

Capillary waveguide fluoroimmunosensor with improved repeatability and detection sensitivity.

An optical capillary waveguide fluoroimmunosensor based on glass capillaries internally coated with an ultrathin poly(dimethylsiloxane) (PDMS) film is presented. The evaluation of the capillaries developed was done in comparison with aminosilanized [3-(aminopropyl)triethoxysilane, APTES] glass and poly(methylpentene) (PMP) capillaries by immobilizing rabbit gamma-globulins on the internal capillary wall. Following reaction with (R)-phycoerythrin-labelled antibody, the capillary was scanned with a laser beam and the fluorescence waveguided through the capillary wall was detected by a photomultiplier placed at one of its ends.

Glycerin suppression of fluorescence self-quenching and improvement of heterogeneous fluoroimmunoassay sensitivity.

Fluorescent labels find wide application in immunoassays and immunosensors as well as in protein and DNA chips. However, the use of fluorescent labels in applications requiring high detection sensitivity is limited by fluorescence self-quenching observed when a relatively high number of fluorescent compounds is introduced in the recognition molecule. Here we describe a simple method that suppresses effectively fluorescence self-quenching observed when highly labeled antibodies are used as labels in immunoassays.

Solid-phase fluoroimmunoassay for the determination of mesotrione--a novel triketone herbicide--in water with direct measurement of the fluorescence onto the solid support.

A straightforward, low-cost fluoroimmunoassay (FIA) for the determination of the new triketone herbicide mesotrione has been developed and optimized. The protein-mesotrione conjugate, immobilized on white opaque microtitration wells competes with the mesotrione in the sample or standard for the limited binding sites of a liquid phase anti-mesotrione antibody. The assay is based on the measurement of fluorescence intensity directly onto the solid support, using a fluorescein labeled second antibody and a fluorescence plate reader.

Simultaneous determination of pesticides using a four-band disposable optical capillary immunosensor.

The development of a four-band capillary optical immunosensor for the simultaneous determination of mesotrione, hexaconazole, paraquat, and diquat is described. Four distinct bands (each corresponding to a different analyte) are created in the internal walls of a plastic capillary by immobilizing protein conjugates of the analytes. To perform the assay, the capillary is filled with a mixture of anti-analyte-specific antibodies together with a standard or sample containing the analyte(s).

The effects of stress exposure on the hypothalamic-pituitary-adrenal axis, thymus, thyroid hormones and glucose levels.

In the present study, an attempt was made to compare three stress models and their effects on the hypothalamic-pituitary-adrenal (HPA) axis, the thymus, the thyroid hormones and the glucose levels. The three different stress models were the chronic mild stress (CMS), the 14-day and the 1-day cold swim stress model. The CMS procedure caused a decrease in thymus weight and rendered no changes on glucose, the adrenocorticotropin hormone (ACTH) or the adrenals.

Increased sensitivity of heterogeneous fluoroimmunoassays employing fluorescein-labeled antibodies by simple treatment of the wells with glycerin solution.

Here we present a simple and rapid procedure that enhances and stabilizes the fluorescence signal determined directly onto the solid phase and increases the sensitivity of heterogeneous fluoroimmunoassays which employ fluorescein as label. The evaluation of the proposed procedure was performed through a heterogeneous immunofluorimetric assay for mouse gamma-globulins in white-opaque microtitration wells. The proposed fluorescence enhancement and stabilization method consists of a 3-min treatment of the wells with a glycerin solution, after completion of the assay, followed by a 15-min incubation of the emptied wells at 37 degrees C.

Free thyroxine solid-analog immunoassays. investigation of the albumin effect on the antibody binding to immobilized thyroxine-protein conjugates.

A reliable one-step, analog-based FT4 immunoassay should be characterized by minimal binding of the serum thyroxine-binding proteins to thyroxine-analogs, used either as liquid-phase tracers or as solid-phase reagents. In this work, we investigated the effect of serum albumin concentration on the anti-T4 antibody binding to immobilized T4-protein conjugates with respect to the molecular weight (MW) and the T4-to-protein molar ratio of the conjugates. It was found that the presence of albumin in the serum sample, at concentrations up to 120 g/L, slightly decreased the antibody binding to the immobilized conjugates (less than 10%).