Abstract: Stable suspensions of coated magnetic particles, preferably resuspendable bioactive particles particularly useful in Magnetic Resonance Imaging, are produced by disrupting, what are presumed to be, crystalline agglomerates of a parent particulate magnetic starting material in the presence of a coating material, such that coating can take place during the disruption. The particles are generally coated in suspension yielding a stable suspension of subdivided particles. With the proper selection of a coating material, preferably a protein or other biochemically or biologically active polymer such as an antibody, a resuspendable (colloidal) bioactive product is obtained.

Abstract: Methods and devices are provided for separation of magnetic particles and/or magnetic-associated substances from non-magnetic associated substances and media. The methods are specifically applicable to biological separation, and utilize a phase phenomenon arising from mutual interactions between suspended magnetic particles and interactions with the suspension medium. The phenomenon is exploited to produce and maintain a distinct, structured phase of magnetic particles, or ferrophase, within a multi-phase liquid system. A ferrophase is established within a separation chamber prior to introducing therein a test sample containing the target substances to be separated. The formation of a ferrophase is used to transport target substances from regions of relatively low magnetic field gradient to regions of relatively high magnetic field gradient within a high-gradient magnetic separation apparatus.

Abstract: A method is provided for direct coating of transiently stable, colloidal particulate magnetic substrates with various synthetic or naturally-occurring polymers, particularly biologically-active peptides and proteins. The resulting coated resuspendable, colloidal magnetic particles are particularly adapted for use in bioanalytical procedures involving affinity separation, or the like. There is also provided a method for selectively binding chemically-treated colloidal magnetic particles to polyelectrolytes, e.g., to facilitate extraction of nucleic acids from cell lysates.

Abstract: A magnetic separator for isolating magnetically-labeled substances of interest, such as immunological agents, from a non-magnetic test medium using a method of high gradient magnetic separation. The target substance is contacted with microscopic magnetic particles having a receptor for binding with the target substance. The test medium containing the magnetic particles is held in a non-magnetic container and placed into a gap within an arrangement of magnets for causing the magnetic particles to adhere to selected locations upon the interior wall of the container. The quantity of magnetic particles may be controlled to cause the magnetic particles collected upon the interior wall to form a monolayer. The magnets are arranged upon a yoke which may provide linear, surrounding multipolar, or partially surrounding multipolar configurations of magnetic pole faces about the gap.

Abstract: Magnetic separation apparatus and methods for separating colloidal magnetic particles from a non-magnetic test medium in which the magnetic particles are suspended. The separator comprises a container holding the non-magnetic test medium, one or more magnetic wires disposed substantially within the test medium in the container and an external magnet for producing a magnetic field gradient within the test medium. According to the method of the invention, the container holding the test medium is positioned in the separator, producing a magnetic field gradient operative to cause the magnetic particles to be attracted to the areas surrounding the magnetized wires and to adhere to the wires. The non-magnetic test medium is separated from the magnetized particles, which may conveniently be washed while adhered to the wires, and subjected to further analysis, preferably while on the wires.

Abstract: A magnetic separator for separating magnetic particles from a non-magnetic test medium is disclosed herein. The magnetic separator includes a non-magnetic container having a peripheral wall with an internal surface area for receiving the test medium, and magnetic means for generating a magnetic field gradient within the container in which the magetic field is stronger in the test medium along the internal surface area of the peripheral wall than in the medium most distant from the wall.

Abstract: Colloidal particles are converted into magnetic microagglomerates via manipulation of their colloidal properties, thereby facilitating their separation from solution.

Abstract: A test system and procedure for quantitatively assaying biological material for a target immunological substance by means of immunochemical binding of immune complexes, comprising the target substance and its immunospecific conjugate, to insolubilized non-immunospecific factor, such as Clq. A sample of biological material suspected of containing the target substance is introduced into the test system including pre-determined amounts of the target substance and its immunospecific conjugate forming immune complexes having a known degree of chemical binding to the non-immunospecific factor. The amount of target substance present in the test sample is determined according to the deviation from the known degree of immunochemical binding caused by the addition of the sample to the test system, by reference to a standard curve.

Abstract: A magnetic-polymer particle, useful in immunoassay techniques and various other biological/medical applications is produced by coprecipitation of transition metals in the presence of a polymer having available coordination sites. These particles are capable of forming stable aqueous suspensions and may be easily resuspended after agglomeration.

Abstract: A process and apparatus for removing immuno-specifically recognizable substances in the form of immune complexes from a solution. The solution containing preformed immune complexes or immune complexes already present therein is contacted with an adsorbent consisting of non-immunospecific factor such as Clq, rheumatoid factor, Fc receptor and Fc receptor-bearing cells.