Chemistry: analytical and immunological testing – Involving an insoluble carrier for immobilizing immunochemicals – Carrier is inorganic
Patent
1998-01-15
2000-10-17
Chin, Christopher L.
Chemistry: analytical and immunological testing
Involving an insoluble carrier for immobilizing immunochemicals
Carrier is inorganic
436501, 436535, 436531, 436173, 436806, 436824, 428402, 42840224, 428403, 428407, 427 213, 427128, 427127, 427215, 427131, 427132, 427214, 427216, 427217, 427221, 427222, 427404, 427338, 427405, 4274071, 427409, G01N 33553, G01N 33566, B32B 516, B05D 512
Patent
active
061330477
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to monodisperse superparamagnetic particles, to their process of production and to their uses, in particular in biology for the isolation of biological molecules.
Monodisperse superparamagnetic particles are disclosed in the prior art. By way of illustration, documents EP-0,106,873 and EP-0,446,260 describe monodisperse superparamagnetic particles comprising a porous core based on a polystyrene/divinylbenzene copolymer in which particles of magnetic iron oxide are incorporated, and a functionalized external layer capable of interacting with nucleic acid probes.
According to the process for producing the particles described in these documents, the magnetic iron oxides are incorporated by precipitation of the corresponding salts. This limits the content of magnetic filler incorporated and makes it possible to obtain the magnetic filler only as a monolayer.
Document EP-0,585,868 describes magnetic particles consisting of a core based on a first polymer and on a magnetic layer covering the core, which layer consists of a second polymer, in which the ferrite-based magnetic material is distributed, and is capable of interacting with an antigen or an antibody, the magnetic material being deposited by precipitation of iron salts.
The magnetic material incorporated is directly exposed to the subsequent treatments of the particles and as a result there is a loss of filler during use of the particles. This may lead to problems, in particular to problems of enzyme inhibition and of denaturation of biological entities.
According to the invention, particles which are superparamagnetic and which have a magnetic filler distributed very homogeneously are used, the content of which may vary between 1 and 80%, in particular from 25 to 80% by weight with respect to the polymer(s) constituting the particles. The present invention makes it possible to achieve high contents of incorporated magnetic filler, in particular since the process employed makes it possible to distribute the magnetic filler in the form of multilayers. This results in a considerable advantage, namely the possibility of effective separation of the particles of the invention from the specimen, without having recourse to the combined action of another separation technique, such as flocculation.
The magnetic filler is in the form of nano-particles which are incorporated in the particles in a substantially irreversible manner, i.e. without loss by release, whatever the subsequent treatments which are applied to them, in particular in the specimen, namely rinsing operations, variations in temperature, in pH, etc.
The properties of the particles of the invention result from their particular structure and particular composition and more specifically from the presence of a constituent heat-sensitive polymer at least for supporting the magnetic material.
A process for obtaining magnetic particles, comprising a core based on a first polymer consisting of a polystyrene and in which a magnetic material is distributed, and a hydrophilic layer covering the core, based on a heat-sensitive polymer consisting of poly(N-isopropylacrylamide), is known from the article by A. KONDO, (A. KONDO, H. KAMURA and K. HIGASHITANI (1994), Appl. Microbiol. Biotechnol., 41, 99-105). The process described comprises the following steps: brought into contact with styrene in the presence of a polymerization initiator and then brought into contact with N-isopropylacrylamide and methacrylic acid, in the presence of the above polymerization initiator.
Bovine serum albumin is fixed to the particles thus obtained in order subsequently to isolate antibodies directed against the bovine albumin serum present in a specimen.
The drawback of these particles occurs in the step for separating them: these particles incorporate a small amount of magnetic filler and furthermore have sizes which vary greatly, considerably limiting the effectiveness of an applied magnetic field for separating the particles. Thus, in order to ensure as efficient as possible a separation of these pa
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Elaissari Abdelhamid
Mandrand Bernard
Pichot Christian
Sauzedde Florence
Bio Merieux
Chin Christopher L.
Do Pensee T.
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