Chemistry: electrical and wave energy – Apparatus – Electrophoretic or electro-osmotic apparatus
Reexamination Certificate
1999-09-03
2001-12-11
Tung, T. (Department: 1743)
Chemistry: electrical and wave energy
Apparatus
Electrophoretic or electro-osmotic apparatus
C204S606000, C204S627000
Reexamination Certificate
active
06328869
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an apparatus for purification of macromolecules in solution and in particular to a cartridge or cassette for use in a macromolecular purification apparatus.
BACKGROUND OF THE INVENTION
European patent No 352286 relates to improvements in the separation of macromolecular solutes by a process known as electrophoretic separation, in particular fixed boundary electrophoretic separation. In fixed boundary electrophoresis, as is explained in more detail below in the description following the Brief Description of the Drawings, a semi-permeable membrane (hereinafter referred to as a separation membrane) acts to separate two streams of liquid carrying macromolecular solutes such as proteins, referred to as the upstream and the downstream. The streams pass between charged electrodes and at least one macromolecular solute migrates across the membrane from one stream to the other under the influence of the electric field. The apparatus also includes flow paths for buffer solution and further semi-permeable membranes, hereinafter referred to as restriction membranes, disposed between the electrodes and the separation membrane. The restriction membranes allow the passage of ions but not macromolecules.
The present invention relates to developments and improvements over the ideas and principals disclosed in EP 352286 and in particular to refinements and improvements to the apparatus to make the technology easier to use and operate.
In particular, it is one desired object of the present invention to provide an apparatus which is easier to fill, empty, clean and reassemble in contrast to existing apparatus such as that described above which tends to be formed substantially integrally with storage tanks, pumps, cooling apparatus and similar features making the apparatus expensive and difficult to handle and clean.
The lack of ease of use of the prior art apparatus is a serious disadvantage and tends to make separation of molecules by electrophoresis an unnecessarily complicated, tedious, time-consuming and expensive procedure.
Thus it is a further object of the present invention to provide an electrophoresis apparatus which is simpler and relatively quicker to operate than existing apparatus to set up and use.
A further problem associated with the prior art id the amount of “downtime” involved after the apparatus has been used and before it can be set up for a further separation. Electrophoresis apparatus is expensive and the downtime is consequently a serious cost disadvantage.
Thus it is a further object of the present invention to provide an apparatus whose downtime is reduced in comparison with prior art apparatus.
A yet further problem of existing electrophoresis apparatus relates to the size of the samples which are typically separated by such apparatus, the amount of sample to be separated can be very expensive, and consequently the smaller the sample which can be separated by the apparatus, the better.
It is a yet further object of the present invention to provide an apparatus which can be used to separate relatively small samples sizes.
Existing electrophoresis apparatus is also very bulky and can take up a large area of laboratory space.
It is a yet further object of the present invention to provide an apparatus which in its preferred embodiment can be relatively compact.
A further problem with existing electrophoresis apparatus is that it can require a relatively high current and voltage to operate.
It is a further object of the present invention to enable an electrophoresis apparatus which uses less power and hence is more economical and also causes less electrical heating to the sample being separated which can damage the sample.
SUMMARY OF THE INVENTION
In a first broad aspect, the present invention provides an apparatus for free flow electrophoresis in which a separation membrane, a first flow path along one side of the separation membrane, and a second flow path along an opposite side of the separation membrane and restriction membranes for separating buffer flow from the flow paths, are housed in a cartridge which can be removed from the apparatus for replacement with another cartridge, after use.
The construction of an apparatus in which the separation membrane and flow paths are defined in a removable cartridge provides a modular system which has substantial advantages of the known prior art. The need to clean, readjust, and re-set the apparatus after a separation has been carried out is reduced. The used cartridge is easily removed and a new cartridge may be simply inserted. The upstream and downstream circuits only require cleaning although the buffer may be replaced if desired.
Thus the present invention advantageously provides an apparatus whose downtime is greatly reduced in comparison with prior art apparatus. This produces substantial savings in terms of time and cost efficiency and may also enable the separation of samples at a more commercial scale than is possible with existing electrophoresis apparatus.
In one particular preferred embodiment, the apparatus includes an upper and a lower connection block which defines inlet and outlet means for feeding liquid into the first flow path (the downstream) and into the second flow path (the upstream), in the cartridge.
This arrangement enable the cartridges to be simply inserted between the two blocks and the blocks may be brought together, by a screw clamp or the like to engage the cartridge.
The upper and lower connection blocks may house electrodes and connection means for connecting the electrodes to a power source.
In one particularly preferred embodiment, the electrodes are made of titanium mesh coated with platinum.
The standard electrodes usually used for prior art electrolytic cells comprise platinum wire. The platinum coated titanium expanded mesh used in accordance with preferred embodiments of the present invention has several advantages over platinum wire in particular the ridged structure is self supporting and less expensive than platinum wire. The mesh also may provide a greater surface area and tends to allow higher currents to pass through the separation unit with less electrical power losses of the electrode. The electrodes may thus have a longer useful life.
The upper and lower connection blocks may be made of any suitable material for example a plastics material. The blocks may be transparent or opaque.
The upper and lower electrodes may be housed in recesses or channels defined in the upper and lower connection blocks, respectively. Those channels may define part of the boundaries of the buffer flow path for the apparatus. The other boundary for the buffer flow path is defined by the restriction membranes housed in the cartridge which form the upper and lower faces of the cartridge. The upper and lower connection blocks may define inlets and outlets for buffer flow.
In a related aspect the invention also encompasses a cartridge for use in the apparatus of the present invention, the cartridge including a housing and containing a separation membrane, a first flow path defined along one side of the separation membrane, and a second flow path defined along an opposite side of the separation membrane and restriction membranes for isolating buffer flow from the first and second flow paths.
The cartridge may further include gaskets positioned either side of the restriction membranes for sealing the components between the upper and lower connection blocks. The first and second flow paths may be defined by first and second grid elements. Each grid element may be generally planar and relatively thin.
The use of a relatively thin planar grid element defining the first and second flow paths may provide substantial advantages over the existing art. First, a relatively thin grid element tends to increase the liquid velocity and pressure and thus may result in a more even distribution of liquid over the separation membrane in the cartridge.
The resultant relatively higher liquid velocity may also assist in inhibiting fouling of the separation membrane.
Also, the volu
Arter & Hadden LLP
Garred John X.
Gradipore Limited
Mizer Susan L.
Noguerola Alex
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