DELFIA

Product and services of interest include genomics, proteomics, custom research and services, and instruments, accessories, consumables and software. PerkinElmer proprietary technologies include time-resolved fluorescence which is employed in the sensitive Wallac DELFIA system and Wallac LANCE homogeneous assay system, and fluorescence polarization, [FP]2 , a robust fluorescence-based technique for receptor binding assays that is both fast and easy-to-use. 

The DELFIA assay, the first effective lanthanide-based immunoassay, was developed and commercialized by the early 1980s.108-112 DELFIA (Dissociation Enhanced Lanthanide Fluoro-ImmunoAssay) is a heterogeneous assay which uses a lanthanide complex based on aminocarboxylate ligands such as EDTA, EGTA, or DTPA, linked to the antibody by reaction of appended isothiocyanate groups (e.g., complex (45)) with nucleophilic residues, particularly amines, on the protein surface (Figure 11). 

Figure 12 Split-probe oligonucleotide sequencing using DELFIA.

BCPDA is a tetradentate ligand, and forms 1 1 complexes in these conditions. The metal ion is thus coordinatively unsaturated, and also binds a number of water molecules, which can lead to non-radiative quenching of the metal-centered excited state (vide supra). These must be removed by drying to achieve optimal luminescence intensity. This form of assay is, in fact, slightly less sensitive than DELFIA. 

DELFIA PCB (soil and food) Hybrizyme http //www.hybrizyme.com/... 

Data are expressed as percentages of users for each assay. Abbreviations ELISA, enzyme-linked immunosorbent assay EIA, electroimmunoassay RIA, radioimmunoassay TIA, turbidimetric immunoassay. Delfia, time resolved immunofluorescence assay. 

Fig. 25. (A) DELFIA (Dissociation Enhanced Lanthanide Fluoro-ImmunoAssay) system. This heterogeneous immunoassay system uses a primary antibody bound to a solid support, to which a variable amount of unlabeled antigen is bound. The secondary antibody is labeled with a non-phospho-rescent lanthanide chelate, which becomes phosphorescent after dissociation from the antibody, due to the addition of an enhancement solution [which typically contains a mixture of sensitizer (typically a (1-diketonate) and micelle inducing surfactant (5). (B) Heterogeneous fluoroimmunoassay using a secondary antibody directly labeled with a phosphorescent lanthanide chelate.

Perkin Elmer Life Sciences Applications of Time-resolved Fluorometry with the DELFIA Method , 2003. http //lifesciences.perkinelmer.com. 

The idea of the use of luminescent lanthanide chelates in bioanalysis can be traced back to the 1980s, when Hemmila (1985) reported a time-resolved fluorometric system using an Eu labeling reagent, which was commercially produced by Wallac Oy company. The system was intended for immunoassay and included the spectrometer for time-resolved measurements. The basic principle of the immunoassay system (DELFIA ) is shown in fig. 1. 

Fig. 1. Assay principle of DELFIA system using a non-luminescent I ll label.

This PCR -> hybridization -> DELFIA type of assay can be performed in a multi-color format. Samiotaki et al. (1997) reported this type of assay using seven different hybridization probes, which are three singly-labeled probes (labeled with Eu, Tb, and Sm), three doubly-labeled probes (labeled with Eu and Tb, Eu and Sm, and Tb and Sm), and one triply-labeled probe (labeled with Eu, Tb, and Sm) (see table 5 and scheme 15 for the chelate ligand). After PCR amplification, the PCR product was allowed to hybridize with one of the seven hybridization probes, washed, detected lanthanide ions by DELFIA , and washed. This cycle was repeated for the remaining six hybridization probes. This procedure enabled detection and identification of seven types of human papilloma virus in one single assay. 

DELFIA , developed by Wallac/PerkinElmer, Inc, is a quite powerful technique not only in usual immunoassays but also in receptor-ligand binding assays. Quite interestingly,... 

Antibodies coated onto MTP wells capture kinase or phosphatase substrate phosphorylation state is detected by anti-phosphopeptide antibody coupled to detector dye can be read by time-resolved fluorescence (DELFIA) technique... 

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