Chemistry: analytical and immunological testing – Involving an insoluble carrier for immobilizing immunochemicals – Carrier is organic
Patent
1996-03-01
1998-02-10
Yoon, Tae
Chemistry: analytical and immunological testing
Involving an insoluble carrier for immobilizing immunochemicals
Carrier is organic
436172, 436800, 523200, 523201, 25230135, 424 129, 424 961, G01N 2164, G01N 33533, C09K 1102
Patent
active
057168555
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a flourescent latex the particles of which contain at least two encapsulated hydrophobia fluorochromes. The invention also relates to a process for the preparation of the said latex and to the application of the latter as a marker, particularly a biological marker.
The latices are aqueous dispersions of polymer particles whose size is generally between 0.05 micron and several microns. On account of their particulate appearance, latices offer a large specific surface, which is exploited advantageously in a large number of applications and particularly in the paper, paint, magnetic tape and recording industries and in biology.
In biology, standard assay techniques use latices by way of support for markers of enzymic or radioisotopic type, so as to allow the quantitative assay of the species present in the medium to be analyzed.
This assay technique by molecular marking using, for example, a radioactive isotope, is extremely precise, reliable and is of great detection sensitivity. However, it has several drawbacks associated with the dispersion of the radioactive sources, the prolonged exposure of the personnel, the variation over time of the emission of the source associated with the half-life of the element and especially with the need, at the end of the analysis to isolate the free reagents from the complexed reagents. Radioactive emission is, in effect, entirely insensitive to the environment of the marker.
For the abovementioned reasons, the technique of analysis by fluorescence has established itself as the most effective alternative for the replacement of these conventional markers.
Fluorescent marking has many advantages when compared with radioactive marking. There is no risk of exposure to radiation. Fluorescent marking has excellent stability over time and it especially gives a finer response on account of the specificity of the emission of fluorescence to certain environmental parameters. There is thus no need to carry out post-analysis separations when it is used.
Nevertheless, the practical use of fluorescence particularly in biological assays (immunology, cell counting, flow cytometry) requires certain problems to be solved.
The fluorescence obtained by simple molecular grafting is of insufficient sensitivity as regards generalized practical application. It is difficult to detect this fluorescence when the concentration of the species present in the medium is less than 10.sup.-9 mol/liter. This considerably limits the use of this technique.
In order to be satisfactory, the sensitivity of the fluorescence should be comparable with that of radioactive marking, which would involve being able to work at concentrations of between 10.sup.-12 and 10.sup.-15 mol of particles per liter.
Moreover, the medium in which the compounds to be assayed are present may interfere with the fluorescence emitted by the fluorochromes (for example Rayleigh or Raman scattering of the water). There are a good many other compounds present, particularly in biological serum, which, under the effect of excitation by light radiation, also emit within a range from 300 to 500 nanometers. It is thus desirable for the fluorescence analysis signal to be above 500 nanometers with the widest possible spectral spacing between excitation and emission.
However, it is known that many lasers commercially available have a wavelength which is precisely between 300 and 500 nanometers; for example, the argon laser emits at 488 nanometers and the helium-cadmium laser emits at 440 nanometers. It is thus desirable to be able to choose a spectrum of excitation based on these wavelengths, even if this causes the spurious excitation of water or of other biological substances, provided that the emission of the latex is shifted towards longer wavelengths.
The very object of the present invention is indeed to overcome these drawbacks and/or to solve the problems mentioned above.
Other advantages afforded by the present invention will also become apparent on reading the description which follows.
Firstly, the invention
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Lerner Dan
Ricchiero Frederic
Richard Joel
Teychenne Dominique
Vaslin Sophie
Societe Prolabo
Yoon Tae
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