Chemistry: analytical and immunological testing – Including sample preparation
Patent
1994-09-08
1997-09-09
Pyon, Harold
Chemistry: analytical and immunological testing
Including sample preparation
436514, 436517, 436536, 436539, 4352872, 4352881, 422 73, G01N 33557, G01N 118
Patent
active
056656050
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a method and apparatus for the aggregation of particles, more particularly for the agglutination of particles via cross-bridging molecules as occurs for example in immuno-agglutination assays, where cross-bridging is via antibody molecules.
BACKGROUND OF THE INVENTION
GB 2 233 089 discloses a method and apparatus for monitoring the aggregation of particles suspended in a liquid, in which a sample of the liquid is subjected to ultrasound to promote aggregation and possible agglutination of particles, and then the particles are allowed to settle onto a meniscus of the sample. A visual inspection of the particles once settled on the meniscus enables a determination of whether an agglutination reaction has occurred: agglutinated cells lie in clumps distributed over the meniscus whereas clumps of non-agglutinated particles dissociate and form a ring around the edge of the meniscus.
The method and apparatus disclose-in GB 2 233 089 is particularly applicable to the detection of Hepatitis B virus, a reaction mixture being formed of a serum sample plus a suspension of appropriate erythrocytes coated with antibody to Hepatitis B surface antigen. Viral agglutination of the erythrocytes gives a positive test reaction.
In GB 2 233 089, ultrasound is coupled via a reservoir into the bottom of a vertical capillary tube containing the sample. The arrangement is not suited to multiple-sample testing because the reservoir, in which the capillary tube stands, must be washed out and refilled for each test; also continuous movement of successive samples through the capillary tube is impractical because the ultrasonic transducer is positioned across one end of the capillary tube.
SUMMARY OF THE INVENTION
We have now devised an improved method and apparatus for rapid aggregation of particles.
In accordance with this invention, there is provided a method for the aggregation of particles suspended in a liquid, comprising containing a sample S of the liquid in a tube, generating a standing wave ultrasound field transverse to the tube, the standing wave exhibiting a progressive change in pressure amplitude transverse to the tube, so that particles in suspension are displaced transversely of the tube to one more predetermined regions, and then terminating the exposure of the sample S to the standing wave and allowing the particles to settle.
Once the particles have settled, they are inspected to determine whether they have remained aggregated or whether they have dissociated. Alternatively, or in addition, the particles can be inspected whilst they are in the process of settling. In any event, the inspection can be carried out by the eye, or by directing a beam of light at the particles and using a sensor to respond to the reflected or transmitted beam.
Preferably the standing wave exhibits a progressive change in pressure amplitude from a first region within the tube to said predetermined region or regions, which are spaced inwards from the inner surface of the tube but preferably are closer to the inner surface than said first region. For example the standing wave may exhibit a pressure amplitude maximum at or adjacent a longitudinal axis of the tube and a pressure amplitude minimum at a said predetermined region spaced inwards from the inner surface of the tube.
Preferably the ultrasound standing wave field extends radially outwards from a longitudinal axis of the tube in different angular directions, and preferably in all angular directions through 360.degree.. Preferably the ultrasound standing wave field is generated by a transducer of tubular form which encircles the tube containing the liquid sample S.
Preferably the sample S of liquid has an upper boundary U and a meniscus at its lower boundary L within the tube, and the particles are allowed to settle onto this meniscus.
The arrangement enables the sample tube to contain several liquid samples S, separated by bubbles of air or other fluid, so that the sample tube can be displaced longitudinally, taking the successive
REFERENCES:
patent: 4615984 (1986-10-01), Stoker
patent: 4795698 (1989-01-01), Owen et al.
patent: 5164094 (1992-11-01), Stuckart
patent: 5227312 (1993-07-01), Grundy
Jepras et al., "Agglutination of Legionella pneumophila by antiserum is accelerated in an ultrasonic standing wave", Journal of Immunological Methods, 120, pp. 201-205 (1989).
Dyson et al., "Segregation and Sedimentation of red Blood Cells in Ultrasonic Standing Waves", Nature, 239, pp. 398-399 (1972).
Whitworth et al., "Transport and harvesting of suspended particles using modulated ultrasound", Ultrasonics, 29, pp. 439-444 (1991).
Bolex Werner
Coakley William Terence
Grundy Martin Alan
Pyon Harold
University College Cardiff Consultants Limited
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