US3498532A - Zonal centrifuge attachment - Google Patents

Description

March 3, 1970 Filed ma 15, 1968 NR. HARBOTT ZONAL CENTRIFUGE ATTACHMENT 3 Sheets-Sheet 1 March 3, 1970 N. R. HARBOTT ZONAL CENTRIFUGE ATTACHMENT 3 Sheets-Sheet 2 Filed May 15 1968 Hllll March 3, 1970 N. R. HARBOTT 3,498,532

ZONAL CENTRIFUGE ATTACHMENT Filed May 15 1968 s Sheefis-Sheet 5 xwi United States Patent O 3,498,532 ZONAL CENTRIFUGE ATTACHMENT Norman Richard Harbott, Sussex, England, assignor to MSE Holdings Limited, Crawley, Sussex, England, a British company Filed May 13, 1968, Ser. No. 728,432 Claims priority, application Great Britain, June 19, 1967, 28,277/ 67 Int. Cl. B04b 11/04, /10, 7/12 U.S. Cl. 233-16 5 Claims ABSTRACT OF THE DISCLOSURE This invention relates to zonal centrifugation used for tissue fractionation and 'virus isolation and concerns a zonal centrifuge attachment.

In zonal centrifugation, a density gradient is maintained in a hollow cylindrical zonal rotor spinning about its axis of symmetry. The gradient and the sample are introduced into the rotor whilst it is spinning by liquid entry and exit lines having a rotating seal with the rotor. The rotor conventionally has septa dividing the rotor into segments to prevent swirling of its contents. The components of the sample migrate through the density gradient in a manner dependent upon their densities and can thus be separated, either by so-called rate zonal separation or by isopycnic zonal separation.

For very high speed work, at tens of thousands of r.p.m., it is advantageous to use a rotor which is tall but which has a relatively small diameter. In addition to conventional means such as a tapered recess at the lower end of the rotor for coupling the rotor to the centrifuge motor, the rotor has a top supporting bearing because of its height.

A problem with such a rotor is that, because of its height, it is used with a special centrifuge having a guard bowl of greater height than in standard centrifuges to accommodate the rotor within the centrifuge.

It is an object of the present invention to provide a zonal centrifuge attachment suitable for a standard centrifuge.

In accordance with the invention, there is provided a,

zonal centrifuge attachment for a centrifuge having a cover, which is to be apertured to accommodate the attachment, the attachment comprising: an open-ended housing to be positioned on said cover so as to be upstanding therefrom and to cover the aperture in said cover; a hollow cylindrical zonal centrifuge rotor having such dimensions, with an axial length greater than its diameter, that said rotor can be supported partially within said housing and will extend through said aperture in said cover when said housing is positioned as aforesaid; coupling means at one end of said rotor for coupling said rotor to the motor of said centrifuge; liquid entry and exit means supported by said housing for introducing liquid into and removing it from said rotor during rotor rotation; and bearing means for rotatably supporting said rotor at its other end relatively to said housing.

For a better understanding of the invention and to show how the same may be carried into effect, reference Patented Mar. 3, 1970 "ice will now be made, by way of example, to the accompanying drawings, in which:

FIGURE 1 is a diagrammatic view of a standard centrifuge partially cut away;

FIGURE 2 is a diagrammatic view of the centrifuge of FIGURE 1 carrying an attachment and again shown partially cut away;

FIGURES 3A and 3B together form a cross-section of an attachment showing parts of a centrifuge in phantom.

FIGURE 1 shows a standard M.S.E. centrifuge operable at 65,000 rpm. The centrifuge comprises a casing 1 having a cover plate 2 adapted to be slid into the illustrated position upon an Oring to give a vacuum-tight seal. The compartment within the casing is to be evacuated by a duct (not shown). The casing contains a centrifuge rotor 3 of titanium coupled to be driven by a motor 4 having a shaft portion 5 of tapered form for engaging in a recess in the underside of the rotor 3. As an indication of the overall dimensions, it is pointed out that the rotor 3 of this embodiment has an axial length of about 5 inches and a diameter of about 7% inches. The casing 1 also contains a bowl 6 secured to the motor 4 and surrounded by piping 7 forming a coil of refrigeration equipment which is not shown. The bowl has an axial length of about 9 /2 inches and a diameter of about 15 inches.

FIGURE 2 shows the centrifuge of FIGURE 1 adapted for operation for zonal centrifugation. It has been found desirable to employ for such centrifuging a special form of rotor having an axial length in excess of its diameter, the diameter being smaller than that of a conventional rotor such as is shown at 3 in FIGURE 1. To accommodate the zonal rotor 8, having sector shaped compartments, the cover plate 2 is provided with an aperture 9 closed by an upstanding open-ended housing 10 covering the aperture 9. The rotor 8 is supported at its upper end by a steadying bearing 17 and extends into the housing 10 which carries an arrangement 11 for continuous feed of liquid to and from the rotor -8 during rotor rotation. In this case, the rotor 8 has a diameter of about 5 inches and an axial length of about 13 inches. The rotor is recessed on its underside to receive the existing shaft portion 5 of the motor 4. The arrangement 11 also has provision for feeding a cooling medium to the top bearing 17 and rotating seal of the attachment.

FIGURE 3 shows the attachment in cross-section. The housing comprises a guard ring 12 recessed into the aperture 9 in the cover plate 2, an O-ring 13 being provided to effect a vacuum-tight seal between the cover plate 2 and the ring 12. An annular plate 14 is bolted to the upper end of the ring 12, this plate 14 being closed by a further annular plate 15 bolted to the plate 14 and carrying the liquid supply and exit arrangement 11. The rotor 8 is also shown in this figure.

In practice, a special apertured cover plate 2 may be provided for the attachment, or the existing cover plate of a standard centrifuge may be adapted by forming the aperture 9 in it and by providing this aperture with an O-ring sealed cover plate (not shown) for operation in the mode illustrated in FIGURE 1. For zonal centrifugation, the guard ring is placed in position on the cover plate 2 and cover plate 2 is slid into its final position. The

rotor is then inserted into the centrifuge to engage the lower end of the rotor with the shaft portion 5 and the plate 14 and its attachment are placed on the ring 12. Bolts 16 are then inserted and tightened to complete the assembly. When a vacuum is produced within the centrifnge, the guard ring 12 is thereby sealed to the cover plate 2.

The described attachment is used conventionally, that is to say the density gradient and the sample are introduced while the rotor is running at low speed, whereafter the rotor is run at high speed until rate ZOnal or isopycnic zonal separation has occured. Then the rotor is slowed down and the entire rotor contents are removed while the rotor is running. It will be apparent that with a modified rotor core the attachment can be used for contiuuous-fiow zonal separation in Which the sample is fed continuously into the rotor running at high speed and the solution in which the sample is suspended is removed continuously. This solution has a density less than that of the lightest part of the gradient.

I claim:

1. A zonal centrifuge attachment for a centrifuge having a cover, which is to be apertured to accommodate the attachment, the attachment comprising: an open-ended housing to be positioned on said cover so as to be upstanding therefrom and to cover the aperture in said cover;

a hollow cylindrical zonal centrifuge rotor having such dimensions, with an axial length greater than its diameter, that said rotor can be supported partially Within said housing and will extend through said aperture in said cover when said housing is positioned as aforesaid; coupling means at one end of said rotor for coupling said rotor to the motor of said centrifuge;

liquid entry and exit means supported by said housing for introducing liquid into and removing it from said rotor during rotor rotation; and

bearing means for rotatably supporting said rotor at its other end relatively to said housing.

2. An attachment as claimed in claim 1, wherein said housing comprises an annular wall at one end of which is an annular plate through which said liquid entry and exit means extend in vacuum-tight fashion and upon which said bearing means is mounted.

3. An attachment as claimed in claim 2, wherein said plate is readily detachable from said annular wall.

4. An attachment as claimed in claim 1, wherein said rotor and said entry and exit means are designed for continuous-flow zonal centrifugation.

5. In a centrifuge having a guard 'bowl closable in vacuum-tight fashion by a cover to define a rotor receiving space and a motor for driving a rotor within said space, the improvement which comprises:

said cover having an aperture permitting access to said space; and open-ended housing mounted on said cover in vacuum-tight fashion and covering said aperture; a hollow cylindrical zonal centrifuge rotor having a length greater than its diameter and extending from said space through said aperture into said housing;

coupling means coupling the end of said rotor within said space to said motor;

bearing means supporting the end of said rotor within said housing with respect to said housing; and liquid entry and exit means for introducing liquid into and removing liquid from said rotor during rotor rotation.

References Cited UNITED STATES PATENTS 2,878,992 3/1959 Pickels 233--26 X 3,050,239 8/1962 Williams 233-26 X 3,304,990 2/1967 Ontko 233--26 3,317,127 5/1967 Cole 233-26 ROBERT W. JENKINS, Primary Examiner US. Cl. X.R.

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