Magnetic aggregating and washing device for in vitro assays and methods of use thereof
Inventors
KAO, Chien-Teng • CHUNG, Yao-Kuang • Lee, Pei-San
Assignees
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Publication Number
US-9063044-B2
Publication Date
2015-06-23
Expiration Date
Abstract
Provided herein are magnetic aggregating and washing devices. Further provided herein are methods using magnetic aggregation to aggregate and wash sample molecules in an in vitro assay.
Core Innovation
The invention relates to a method for washing a sample in an assay by coupling a microtiter plate with a magnetic structure, where the microtiter plate sits on top of the magnetic structure and a well of the microtiter plate comprises a sample and a plurality of magnetic beads. The magnetic structure comprises a plurality of magnets each having a first pole and a second pole with opposite magnetic properties, and adjacent magnets are oriented such that the first pole of a first magnet faces the first pole of a second magnet.
The method rotates the microtiter plate such that the microtiter plate and the magnetic structure move together at a first speed for a first duration to distribute the plurality of magnetic beads in the well. In this first rotation step, the relative centrifugal force produced by rotating the microtiter plate exceeds the magnetic force between the magnetic beads in a well and the magnetic structure, enabling bead distribution.
After distributing the beads, the method rotates the microtiter plate at a second speed for a second duration to aggregate a majority of the plurality of magnetic beads at a portion of the well, with the second speed different from the first speed. In the second rotation step, the rotation produces a relative centrifugal force that does not exceed the magnetic force between the magnetic beads in a well and the magnetic structure, thereby maintaining magnetic aggregation of the majority of the beads at the defined well portion for washing.
The disclosed approach addresses washing performance by using two different rotation speeds and durations to control the relationship between relative centrifugal force and magnetic force during bead handling. This enables distribution of beads away from magnetic attraction during the first rotation step and aggregation of a majority of beads at a portion of the well during the second rotation step to support removal of well contents with reduced bead loss, as described with magnetic bead distribution and washing performance in the document.
Claims Coverage
The document includes two independent claims. Each independent claim centers on a two-speed rotation protocol for distributing and then aggregating magnetic beads in a microtiter plate coupled to a specifically oriented magnetic structure, with one independent claim further requiring that the relative centrifugal force during aggregation does not exceed the magnetic force.
Magnetic structure with adjacent like-pole facing orientation
The magnetic structure comprises a plurality of magnets each having a first pole and a second pole with opposite magnetic properties, wherein a first magnet and a second magnet are oriented such that the first pole of the first magnet faces the first pole of the second magnet, the first magnet adjacent to the second magnet in the magnetic structure.
First rotation step distributing magnetic beads by exceeding magnetic force
Rotating the microtiter plate and the magnetic structure together at a first speed for a first duration to distribute the plurality of magnetic beads in the well, wherein the rotation at the first speed produces a relative centrifugal force that exceeds the magnetic force between the magnetic beads in a well of the microtiter plate and the magnetic structure.
Second rotation step aggregating majority of magnetic beads at a well portion
Rotating the microtiter plate and the magnetic structure together at a second speed for a second duration to aggregate a majority of the plurality of magnetic beads at a portion of the well, the second speed different from the first speed.
Second rotation step ensures relative centrifugal force does not exceed magnetic force
In the second rotation step, the rotation of the microtiter plate at the second speed produces a relative centrifugal force that does not exceed the magnetic force between the magnetic beads in a well of the microtiter plate and the magnetic structure.
Across the independent claims, the core claim coverage is the coupling of a microtiter plate to an oriented magnetic structure and the use of two different rotation speeds and durations to switch bead behavior between distribution and aggregation, with relative centrifugal force exceeding magnetic force in the first step and, in one independent claim, not exceeding magnetic force in the second step.
Stated Advantages
Enables bead distribution in the well by using relative centrifugal force exceeding the magnetic force.
Enables aggregation of a majority of the magnetic beads at a portion of the well by using relative centrifugal force not exceeding the magnetic force.
Supports removal of well contents with reduced bead loss, as described in the disclosed washing performance.
Documented Applications
In vitro assays using a microtiter plate with magnetic beads, including fluorescent wash assays and washing to recover bound material.
Magnetic bead washing and aggregation in biological sample processing, including blood samples.
High-throughput washing and aggregation cycles using antibody-conjugated magnetic beads for protein yield from processed tissue samples.
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