US3396096A - Magnetic holder for electrophoresis material - Google Patents

Description

MAGNETIC HOLDER FOR ELECTROPHORESIS MATERIAL Filed March 15, 1965 J. M. BELOTE ET AL Aug. 6, 1968 2 Sheets-Sheet l FIG 2 INVENTORS JAMES M. BELOTE DONALD CHURCHILL HERBERT J. EARLE CHARLES GELMAN 4 W W 1 m ATTORNEYS 1968 I M. BELOTE ET A1. 3,396,096

MAGNETIC HOLDER FOR ELECTROPHORESIS MATERIAL Filed March 15, 1965 2 Sheets-Sheet 2 INVENTORS DONALD HERBERT J. EARLE HARLES GELMAN W M W M A T TOR/VEVS United States Patent 3,396,096 MAGNETIQ HOLDER FOR ELECTROPHORESIS MATERIAL James M. Relate, Donald Churchill, Herbert J. Earle, and

Charles Gelrnan, Ann Arbor, Mich, assignors to Gelman Instrument Company, Ann Arbor, Mich., a corporation of Michigan Filed Mar. 15, 1965, Ser. No. 439,654 7 Claims. (Cl. 204-499) This invention relates to a magnetic holder for electrophoresis material and more particularly to an electrophoresis chamber and combined apparatus for holding electrophoresis material.

As a general background, it might be stated that electrophoresis is a name applied to a technique used in medical research and diagnosis which involves analyzing the molecules of body fluids such as serum, proteins, hemoglobin and other protein substances that vary in molec ular weight. The process requires passing an electric current through a strip of filter material, gel, or porous plastic that has had a sample fluid applied to it. The electric current forces the sample molecules to move along the strip, with distances depending on the charge, molecular weight, and size, that is, a certain prescribed current will move a light molecule farther than a heavier one. The result on a strip of filter material is a pattern of well-defined bands which are then sometimes colored to facilitate the examination and analysis.

The electrophoresis process involves the use of filter material which is apt to be rather delicate and subject to fracture and breaking. It usually consists of small strips of material about 1" in width and 6 in length but in some cases the strips are 20" long and of a wider width. These strips are bridged over two ridges in an electrophoresis chamber and an electrical potential is applied to the paper generally by letting the ends submerge into two separate bodies of liquid which are subjected to the proper electrical circuit or by using Wicks to connect the wetted filter with the liquid body. It has been a problem to fasten the ends of these strips suitably in a manner to prevent the sagging of the strip which might cause a malfunction of the process and to prevent damage or injury to the strip itself. This has been done in the past by resilient clamps and other clamping devices held by gravity or mechanical force but the problem has never been successfully solved.

It is an object of the present invention to include in the electrophoresis chamber a magnetic holding arrangement which is extremely simple and inexpensive and yet one which permits firm clamping of the sample strips in a manner which tends to apply slight tension to the strips to maintain suitable tension thereon as the strips bridge the supports.

It is a further object of the invention to provide a magnetic holding arrangement composed of elements which position in a manner to grip the electrophoresis material in a positive way, the elements being so provided with indicia that they may be properly applied relative to the polarity of the magnetic holding devices, thus insuring a positive positioning and the intended holding function.

Other objects and features of the invention relating to details of construction and operation will be apparent in the following description and claims.

Drawings accompany the disclosure and the various views thereof may be briefly described as:

3,396,096 Patented Aug. 6, 1968 FIGURE 1, a perspective view of an electrophoresis chamber with cover removed.

FIGURE 2, a plan view of an electrophoresis chamber.

FIGURE 3, a sectional view on line 3-3 of FIGURE 2 with a cover in position.

FIGURE 4, a sectional view on line 4-4 of FIGURE 2 with cover in position.

Referring to the drawings:

The electrophoresis chamber is preferably formed as a shallow tray 20 which can be molded of a plastic glass or ceramic material, this tray having a center partition wall 22 extending between ends 24 and 26 about midway between sides 28 and 30. Between the central partition 22 and the respective walls 28 and 30 are elongate support ridges 32 and 34 which extend outwardly from the end wall 26 to a point just short of the end wall 24. These support ridges 32 and 34 are higher than the central septum wall 22. In general, the septum wall is about onehalf the heighth of the outer walls of the chamber and the support ridges are about two-thirds the heighth of the outer walls. It the structure is molded plastic, the center partition and the support ridges can be molded into the structure so that they are hollow as shown in the sectional view used in FIGURES 3 and 4. This provides an elongate chamber 36 and 38 below the support ridges 32 and 34. Also molded into the bottom are small elongate depressions which provide supporting bosses 40 on the bottom of the tray.

The end wall 26 has two connecting posts 42 for the attachment of electrical connections and from the inside of these posts are electrical conductor elements 44 and 46 extending downwardly into the tray on opposite sides of the partition wall 22. A cover for the device is preferably formed of a transparent sheet of plastic material 50 which has a fairly snug fit on the top of the tray 20. This cover has bosses 52 for-med therein to rigidity the cover and to provide drip areas for liquid which may condense on the cover.

On the inside undersurface of the outside wall of the ridges 32 and 34, extending substantially the length of the tray, is positioned an elongate strip of magnetic material. This is preferably made of permanent magnetic material. However, it may be a metal alloy capable of attracting a magnet.

One embodiment can be molded strip of rubber or thermoplastic containing magnetic particles which creates a permanent magnet in the rubber. This can be fastened in place by a suitable adhesive to the inside surface on the ridge 32 or 34 or it can be molded into the plastic as the tray is formed. Other methods of fastening can be utilized. The strip is preferably of narrower width than the overall height of the supporting ridges 32-34 so that the strip can lie spaced downwardly from the top of the ridge. The strip material has a definite polarity characteristic and it is preferable that the two strips have a polarity in the same direction. In FIGURE 3, the strip 60 is shown with a point 62 and a tail formation 64 to indicate this polarity.

To cooperate with these strips, there is provided a plurality of short holding elements also formed with an arrow configuration as shown in FIGURE 1. These elements 70 are also of magnetic material. They can be of metal but are preferably formed of the magnetic rubber stripping previously described. These short elements also V have a polarity in the direction of the arrow in which they are formed and they work best if disposed in the 3 proper relation to the underlying magnetic strip pointing toward the electrodes of the electrophoresis chamber. The rubber material also has the advantage that it has a frictional engagement with the electrophoresis strips 80 which are to be positioned in a bridging relation over the support ridges 3234.

When the electrophoresis material is disposed over these ridges, the holding elements 70 are gently pressed onto the material preferably from the top and they thus have a tendency to move down by reason of the magnetic forces, pulling the strip taut as they move. This tendency of the elements 70 to move down toward the magnetic field, opposite poles attracting each other, applies a slight tension on the specimen strips 80 which is maintained by friction and the forces of attraction between the strips and holding elements as the electrophoresis process proceeds.

Certain magnetic rubber stripping that is available commercially has a thin layer of magnetic rubber material on one side of the stripping backed by ordinary rubber material. There is a north pole at one elongated edge of the magnetic layer and a south pole at the other elongated edge of the layer, both poles being on the same side as the stripping. If the holding elements 70 and the strips 60 are made of such magnetic rubber stripping, each piece of the stripping is a permanent magnet. In order to have a given element 70* and a strip 60 attract each other and hold the electrophoresis material on a support edge, the holding element should be oriented such that its north pole is opposite the strips south pole and its south pole is opposite the strips north pole. This is because opposite poles of two magnets attract each other.

The arrow configuration for the strips and holding elements helps an operator to orient the holding elements properly without requiring him to identify their poles. Referring to FIGURE 3, the strip 60 shown there has a point 62 at its right-hand end and a tail '64 at its lefthand end. Assume that there is a north pole all along the upper elongated edge 63 of strip 60 and a south pole all along the lower elongated edge 64. As viewed in FIGURE 3, these poles are at the back side of the strip where it abuts the vertical wall of support ridge 34. Considering now one of the holding elements 70 shown in dashed lines, it has a point 72 and a tail 74 at the same respective ends as the strip 60. However, the poles of element 70 are inverted relative to those of strip 60, the north pole being along the lower edge and the south pole being along the upper edge. The magnetic layer of holding element 70 abuts the electrophoresis material 80 (FIGURE 4) and faces the magnetic layer of strip 60 on the other side of support ridge 34.

It is not essential to have both the strips 60 and holding elements 70 act as permanent magnets. One or the other may be made of non-permanent magnetic material such as iron or other suitable metal. In this case, it is not necessary to orient the holding elements as carefully, but it is desirable, nevertheless, to use an elongated holding element and apply it to the support ridge parallel to and slightly above a given strip 60 such that the element will slide down the support ridge to a position directly opposite the strip as illustrated in FIGURE 4, thereby tensioning the electrophoresis material as previously described. Consider the example where the strips are permanent magnets and the holding elements are made of nonpermanent magnetic material. The magnetic field of the strips has lines of force (flux lines) which leave from its north pole, curve around and enter at its south pole. These lines of force pass through the holding element and cause it to act as a temporary magnet such that it is attracted to the strip and holds the electrophoresis material 80 in place. As has been indicated, the same result is achieved if the holding elements 70 are permanent magnets and the strips 60 are made of non-permanent magnetic material.

It will be understood, of course, that in the process the chamber is filled with a suitable electrolytic bath 82 of suflicient depth to reach the ends of the strips as they are disposed over the supporting ridges 32-34. The specimen strips are preferably formed of a microporous cellulose polyacetate that gives a uniform pore distribution and eliminates impurities which might impair the electrophoresis process. The interlocking microporous cells of this material reduce electrical resistance to the flow of current and the material does not absorb protein. It will be seen that it is very simple to detach the specimens once the electrophoresis process is com pleted. This is simply a matter of removing the small elements 70 and then removing the strips for further analysis.

It will be appreciated that the electrophoresis chamber itself is, as previously indicated, preferably formed of a plastic material which is molded into shape and which has a dielectric characteristic, the thickness of the Walls being such that the magnetic forces between the strips 60 and the elements 70 can be effective to the purpose stated.

We claim:

1. In an electrophoresis chamber having spaced support ridges for bridging specimen strips, a plurality of magnetic elements positioned on opposite sides of a wall of a supporting ridge, one of said elements being removable to selectively engage a specimen strip and hold it against a supporting wall by the force of the electromagnetic attraction of said elements.

2. In an electrophoresis chamber having spaced support ridges for bridging specimen strips, a plurality of holding elements formed of magnetic material, said elements being selectively positioned on the outside of said support ridges each to engage a portion of the end of the specimen strip to hold the strip in bridging relation between said ridges, and means to create a magnetic field to attract said elements toward said support ridges to create a frictional engagement with the surface of said ridges wherein said elements are magnetically supported.

3. An electrophoresis chamber comprising a relatively shallow tray of formed dielectric material having hollow supporting ridges formed in the bottom thereof in separate chambers within the said tray, said ridges extending upwardly from the bottom of said tray to serve as a support for bridging specimen strips, and a strip of magnetic material positioned on the inner surface of the outside wall of said supporting ridges, said strip of magnetic material being adapted to cooperate magnetically with a plurality of short magnetic elements positioned selectively on the outside surface of the outside wall of said ridges to create a frictional engagement with the end of a specimen strip interposed between said elements and said outer surface.

4. A device as defined in claim 3 in which the strip of magnetic material is a permanent magnet having a north pole along one edge and a south pole along the other edge, and said elements have a north and south pole spaced similarly to that of the strip wherein the elements are attracted to the wall of the ridge to a fixed position.

5. A device as defined in claim 3 in which the strip of magnetic material has linear-1y extending north and south pole regions spaced laterally of the strip for cooperation with said magnetic elements which have a north and south pole region spaced substantially similar to those of the strip wherein the elements are attracted to the Wall of the ridge to a fixed position.

6. A device as defined in claim 5 in which the elements are provided with indicia to indicate a position of application in which mutually attracted pole areas of the strip and the elements will register.

7. In an electrophoresis chamber having spaced supports for specimen strips arranged in bridging relation over said supports, a means of securing the ends of said strips comprising a strip of magnetic material disposed longitudinally along said supports, and a plurality of short pieces of magnetic material removably positioned over the ends of the specimen strips and acting to hold said strips on said spaced supports by the force of magnetic attractions between said strip of magnetic material and said pieces.

References Cited UNITED STATES PATENTS 2,557,399 6/1951 Teetor 335-285 2,693,370 11/1954 Wheatley 335-285 6 McDonald et a1. 204-180 Pickels et al 204-299 Atkinson 248-206 Daline 248-206 Schumacher 204-180 J OHN H. MACK, Primary Examiner.

E. ZAGARELLA, Assistant Examiner.

Claims (1)

1. IN AN ELECTROPHORESIS CHAMBER HAVING SPACED SUPPORT RDGES FOR BRIDGING SPECIMEN STRIPS, A PLURALITY OF MAGNETIC ELEMENTS POSITIONED ON OPPOSITE SIDES OF A WALL OF A SUPPORTING RIDGE, ONE OF SAID ELEMENTS BEING REMOVABLE TO SELECTIVELY ENGAGE A SPECIMENT STRIP AND HOLD

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