Magnetic immobilization and manipulation of biological entities

An apparatus for immobilizing magnetically-labeled entities suspended in a fluid medium, the apparatus comprising:

• magnetic means for producing a magnetic field;
• a nonmagnetic vessel defining a chamber for containing the fluid medium within said magnetic field, said vessel having a longitudinal axis and two opposed ends spaced along said longitudinal axis, wherein said longitudinal axis is aligned perpendicularly to flux lines of said magnetic field;
• a ferromagnetic collection structure supported within the chamber for causing a localized intensification of the magnetic field within the vessel whereby the magnetically-labeled entities are attracted toward said structure, said ferromagnetic collection structure comprising a substantially linear elongated member aligned in parallel with said longitudinal axis and spanning between said opposed ends, said vessel having an aperture for defining an observation path perpendicular to the longitudinal axis for allowing substantially unobstructed microscopic observation of entities attracted to said collection structure, and for allowing lateral physical access to the entities;
• and
• a collection surface coextensive with the elongated member of said ferromagnetic collection structure, intersecting said observation path, and immobilizing the entities for said microscopic observation and physical access along said path.

An apparatus for immobilizing magnetically labeled entities suspended in a fluid medium, the apparatus comprising:

• magnetic means for producing a magnetic field;
• a non-magnetic vessel having a base configured for support upon a translatable stage for translating the vessel within the magnetic field, the vessel defining a chamber bounded by interior surfaces of the vessel for containing the fluid medium within said magnetic field, said vessel having a longitudinal axis and lateral axes defining a chamber having a width and a height, and two opposed ends intersecting the longitudinal axis to define a chamber length, and said vessel having means for defining a lateral observation path including a transparent member that is transparent to at least a selected portion of the electromagnetic spectrum for allowing microscopic observation of the immobilized entities;
• a ferromagnetic collection structure supported in the vessel in parallel with the longitudinal axis for causing a localized intensification of the magnetic field within the chamber whereby the magnetically-labeled entities are attracted toward said structure, said ferromagnetic collection structure comprising a substantially linear elongated member spanning between said opposed ends and having an effective diameter substantially less than the chamber height and width;
• and
• a longitudinal collection surface coextensive with said ferromagnetic collection structure and intersecting said observation path to immobilize the entities for said microscopic observation along said path.

An apparatus for immobilizing magnetically-labeled microscopic biological specimens in a fluid medium for microscopic observation, comprising:

• a non-magnetic vessel movably supportable relative to a microscope, the vessel having a pair of lateral axes that are orthogonal to one another and a longitudinal axis that is orthogonal to said lateral axes, a chamber for containing the fluid medium and having a substantially flat transparent surface providing an observation path into the chamber along one of said lateral axes;
• a ferromagnetic collection structure comprising a linear elongated member positioned in parallel with the longitudinal axis of the chamber for causing a localized intensification of an applied magnetic field within the vessel whereby the magnetically-labeled specimens are attracted toward the structure;
• and
• a collection surface coextensive within the elongated member of the collection structure and having a diameter less than both lateral dimensions of the chamber measured along said lateral axis to immobilize a linear monolayer of magnetically-labeled specimens thereon, and intersecting the observation path to hold said linear monolayer within the focal plane of the microscope.