Chemiluminescence

Chemiluminescence describes the emission of light that occurs as a result of chemical reactions. These reactions frequently involve the release of large amounts of energy. This energy is dissipated in the form of photons when electronically excited molecules, produced as a result of the reaction, relax to a stable ground state. The unique ability of chemiluminecence to provide a high sensitivity detection system has been exploited in medical diagnostics through the use of aryl Acridinium Ester (AE) compounds.

The technology for linking AE compounds to binding reagents such as antibodies or oligonucleotide probes is well established. These labelled reagents can be designed to target specifically an infinite range of substances of biomedical interest which are then quantified by the intensity of the light generated in the chemiluminescent reaction. Such assays were initially developed to investigate human diseases by analysing changes in blood constituents such as hormones.

Subsequently, they have been applied to the detection and monitoring of tumour products, infectious agents such as HIV, markers of coronary heart disease and the gene mutations that give rise to inherited diseases. Acridinium based assays have been developed in a wide range of assay formats including fully automated systems (eg Centaur, Siemens Medical Systems; Tigris, Gen-Probe Inc) and microtitre plate immunoassays.

These analytical methods are not confined to applications in the clinical laboratory. They can, for example, be used to assess the toxicological impact of environmental pollutants through monitoring changes in the expression of marker genes in organisms, tissues and cell lines. The sensitivity of detection, long-term stability and ease of use combine to make acridinium labels a logical and preferable alternative to radioactivity.

Chemiluminescence Products

EIA / ELISA

Enzyme-Linked ImmunoSorbent Assay, or ELISA, is a biochemical technique used mainly in immunology to detect the presence of an antibody or an antigen in a sample.

The ELISA has been used as a diagnostic tool in medicine and plant pathology, as well as a quality control check in various industries. In simple terms, in ELISA an unknown amount of antigen is affixed to a surface, and then a specific antibody is washed over the surface so that it can bind to the antigen.

This antibody is linked to an enzyme, and in the final step a substance is added that the enzyme can convert to some detectable signal. Thus in the case of fluorescence ELISA, when light is shone upon the sample, any antigen/antibody complexes will fluoresce so that the amount of antigen in the sample can be measured.

ELISA Products

Immunoblot

The Immunoblot is a method to detect a specific protein in a given sample of tissue homogenate or extract. It uses gel electrophoresis to separate native or denatured proteins by the length of the polypeptide (denaturing conditions) or by the 3-D structure of the protein (native/ non-denaturing conditions).

The proteins are then transferred to a membrane (typically nitrocellulose or PVDF), where they are probed (detected) using antibodies specific to the target protein. There are now many reagent companies that specialize in providing antibodies (both monoclonal and polyclonal antibodies) against many thousands of different proteins.

Commercial antibodies can be expensive, though the unbound antibody can be reused between experiments. This method is used in the fields of molecular biology, biochemistry, immunogenetics and other molecular biology disciplines.

Immunoblot Products

Multiplex

The FIDIS Multiplex System is a flexible analyzer based on the principles of flow cytometry that is designed to meet the needs of laboratory medicine and the care of patients, as well being used in the research environment.

The system enables you to multiplex (simultaneously measure) up to 100 analytes in a single microplate well, using very small sample volumes.

The system delivers fast and cost-effective bioassay results on many assay formats including nucleic acid assays, receptor-ligand assays, immunoassays and enzymatic assays.

Multiplex Products

NanoCones

The NanoCones technology is one of the most innovative surface coating technologies for diagnostic and bioanalysis. Its most highlighted feature is the precise control of regular spacing between biomolecules and to mimic solution-phase behavior on the surface. This feature offers tremendous potential for studying genetic variations or gene expressions with a DNA microarrays and biomolecular interactions with a Bio-AFM. In addition, this technology is not limited to the above two research areas, but widely applicable to other fields such as protein microarrays, ELISA, bio/chemical sensor, bead assay, affinity-based separation, SPR spectroscopy, etc.

RIA

Radioimmunoassay (RIA) is a scientific method used to test antigens (for example, hormone levels in the blood) without the need to use a bioassay. It involves mixing known quantities of radioactive antigen (frequently labeled with gamma-radioactive isotopes of iodine attached to tyrosine) with antibody to that antigen, then adding unlabeled or "cold" antigen and measuring the amount of labeled antigen displaced.

Initially, the radioactive antigen is bound to the antibodies. When "cold" (unlabeled, quest) antigen is added, the two compete for antibody binding sites - at higher concentrations of "cold" antigen, more of it binds to the antibody, displacing the radioactive variant. The bound antigens are separated from the unbound ones.

One method of separation used initially was the use of a second antibody directed against the first for precipitation and centrifugation. The use of charcoal suspension for precipitation was extended but replaced later by Drs. Werner and Acebedo at Columbia University for RIA of T3 and T4.[1] An ultramicro RIA for human TSH was published in BBRC (1975) by Drs. Acebedo, Hayek et al.[2] The free hormone stays in the supernatant, the radioactivity of which is measured and a binding curve is plotted.

The technique is both extremely sensitive and specific, but it requires special precautions (because radioactive substances are used), sophisticated apparatus, and is expensive. The technique has been largely replaced by the ELISA method where instead of a radioactive signal, the antigen-antibody reaction is measured by colorometric signals.

The RIA was developed by Rosalyn Yalow and Solomon Aaron Berson in the 1950s.[3] Rosalyn Sussman Yalow received the 1977 Nobel Prize in Medicine for the development of the RIA for insulin. The precise measurement of minute amounts of such a hormone was a key event in endocrinology.

RIA Products