U.S. patent application number 09/833616 was filed with the patent office on 2001-08-02 for method and a device for dialysis of liquid samples.
Invention is credited to Alam, Aftab.
Application Number | 20010010298 09/833616 |
Document ID | / |
Family ID | 26750799 |
Filed Date | 2001-08-02 |
United States Patent
Application |
20010010298 |
Kind Code |
A1 |
Alam, Aftab |
August 2, 2001 |
Method and a device for dialysis of liquid samples
Abstract
A method and a device for dialysis having a dialysis reservoir
and a collection reservoir. A sample is placed in the dialysis
reservoir for dialysis. After dialysis, dialysis reservoir is
centrifuged and the dialyzed sample is collected in the collection
reservoir.
Inventors: |
Alam, Aftab; (St. Louis,
MO) |
Correspondence
Address: |
ARENT FOX KINTNER PLOTKIN & KAHN, PLLC
SUITE 600
1050 CONNECTICUT AVENUE, N.W.
WASHINGTON
DC
20036-5339
US
|
Family ID: |
26750799 |
Appl. No.: |
09/833616 |
Filed: |
April 13, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09833616 |
Apr 13, 2001 |
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09192999 |
Nov 16, 1998 |
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6217772 |
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09192999 |
Nov 16, 1998 |
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08840221 |
Apr 11, 1997 |
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60070119 |
Dec 31, 1997 |
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Current U.S.
Class: |
210/646 ;
210/257.2; 210/321.6 |
Current CPC
Class: |
Y10T 436/255 20150115;
B01D 61/28 20130101; B01D 61/30 20130101; G01N 2001/4016 20130101;
Y10T 436/25375 20150115; B01D 17/085 20130101; B01D 17/0217
20130101 |
Class at
Publication: |
210/646 ;
210/257.2; 210/321.6 |
International
Class: |
B01D 061/30 |
Claims
What I claim my invention is.
1. A device for dialyzing liquid samples, comprising: a dialysis
reservoir for receiving samples for dialysis, said reservoir having
an open end and an end opposite the open end, the end opposite the
open end closed with a member comprising a dialysis membrane, the
dialysis reservoir is adapted for centrifugation; a collection
reservoir having an open end and an end opposite the open end which
is closed, the open end of the collection reservoir is fastened to
the open end of the dialysis reservoir, and the collection
reservoir is adapted for centrifugation.
2. The device of claim 1 further comprising a floatation device for
securing and floating the dialysis reservoir in a dialysis buffer
in a manor that allows the dialysis membrane to contact the
dialysis buffer.
3. The device according to claim 1 wherein the dialysis reservoir
includes a shoulder for securely positioning the open end of the
dialysis reservoir onto the open end of the collection
reservoir.
4. The device according to claim 1 wherein the collection reservoir
includes a shoulder for securely positioning the open ends of the
dialysis reservoir onto the open end of the collection
reservoir.
5. The device according to claim 1 wherein the dialysis reservoir
and the collection reservoir have screw thread means for securing
the open end of the dialysis reservoir in to the open end of the
collection reservoir.
6. The device according to claim 5 wherein the dialysis reservoir
further comprises a gasket to contact the dialysis membrane, said
gasket is positioned nearer to the open end of the dialysis
reservoir and when the open end of the collection reservoir is
engaged with the open end of the dialysis reservoir the open end of
the collection reservoir presses against the gasket.
7. The device according to claim 1 wherein the dialysis reservoir
further comprises an outer element sleeving over an inner
element.
8. The device according to claim 7 wherein said outer element and
said inner element have structure elements to restrict the rotation
of the outer element sleeving over the inner element.
9. The device according to claim 7 wherein said inner element has
screw threads for engaging the open end of the collection
reservoir.
10. The device according to claim 9 wherein the dialysis membrane
is secured between the outer element and the inner element to seal
the end opposite the open end of the dialysis reservoir.
11. The device according to claim 10 wherein a gasket contacts the
dialysis membrane and the collection reservoir.
12. The device according to claim 10 wherein a gasket means is
secured between the outer and the inner elements such that said
gasket means is nearer to the open end of the dialysis reservoir
and presses against the dialysis membrane and the collection
reservoir.
13. The device according to claim 1 wherein said collection
reservoir is shaped as a centrifuge tube.
14. The device according to claim 1 wherein the dialysis reservoir
is mounted on the collection reservoir during dialysis.
15. The device according to claim 1 wherein the dialysis membrane
is fused into the body of the dialysis reservoir as an integral
part.
16. The device according to claim 1 wherein the collection
reservoir is a centrifuge tube.
17. A method for dialyzing a liquid sample, comprising: depositing
a sample for dialysis into a dialysis reservoir, the dialysis
reservoir having an open end and the end opposite the open end is
sealed with a dialysis membrane, the dialysis reservoir is designed
to be subjected to centrifugal force in a centrifuge; positioning
the dialysis reservoir in a dialysis buffer such that the dialysis
membrane of the dialysis reservoir makes contact with the dialysis
buffer; and after dialysis is complete, centrifuging the dialysis
reservoir to allow migration of the dialyzed sample through the
open end of the dialysis reservoir into a collection reservoir
positioned on the open end of the dialysis reservoir.
18. A method according to claim 17 wherein the dialysis sample is
deposited directly into the dialysis reservoir and after dialysis
the sample is collected into the collection reservoir by
positioning the open ends of the collection reservoir on the open
end of the dialysis reservoir and subjecting the assembly to
centrifugation in the orientation which allows centrifugal
migration of the dialyzed sample through the open end of the
dialysis reservoir into the collection reservoir.
19. A device for dialysis of liquid samples, comprising: a dialysis
reservoir having an open end and the end opposite the open end is
closed with a dialysis membrane, the open end is adapted to receive
a collection reservoir for collection of sample after dialysis by
centrifugation.
20. A method of fabricating a dialysis reservoir comprising:
forming a through-hole in a cap having a depending skirt so that
the through-hole is defined by a lip, the inside surfaces of said
skirt being threaded, positioning a gasket through the skirt so
that it contacts the inside surfaces of the lip; and fastening a
dialysis membrane on the gasket.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is continuation-in-part of co-pending
application Ser. No. 08/840,221 filed on Apr. 11, 1997. This
application also claims priority from provisional patent
application Ser. No. 60/070,119 filed on Dec. 31, 1997.
FIELD OF THE INVENTION
[0002] A method and a device for dialysis of samples.
BRIEF HISTORY OF THE INVENTION
[0003] There are many devices currently available in the market for
dialyzing small sample volumes. These devices require advanced
preparation, including setting up before a sample can be dialyzed.
A common feature of all such dialysis devices is that the sample
must be transferred into the dialysis device and after dialysis the
sample must be extracted from the dialysis device. Extraction, is
accomplished using a pipetting device. U.S. Pat. No. 5,503,741
discloses one such dialysis device. Dialysis devices have also been
fabricated by wrapping dialysis membranes on test tubes.
[0004] When dealing with small volume samples, one of the major
problems is a loss of sample due to the transfer of samples to and
from the dialysis equipment. When sample is present in such a small
volume and not readily available the loss of sample becomes a
critical consideration. Therefore, there is a need to develop a
method and a device for dialysis that does not require the transfer
of samples out of the dialyzer and which minimizes handling
loss.
[0005] The present invention relates to a method and a device for
the dialysis of sample in which the sample is dialyzed in a
container device which can be centrifuged for collection of the
dialyzed sample. The dialysis device or the part that collects the
dialyzed sample can also be used to store the dialyzed sample which
minimizes handling of the dialyzed sample. The present invention
also relates to a method of fabricating a dialysis reservoir and a
device for fabricating the dialysis reservoir.
SUMMARY OF THE INVENTION
[0006] This invention relates to a method and a device for dialysis
of liquid samples. According to the present invention the liquid
sample to be dialyzed is deposited into a dialysis reservoir, the
dialysis reservoir has an open end, and the end opposite the open
end is closed with a dialysis membrane, preferably a semipermeable
dialysis membrane. The open end of the dialysis reservoir is
adapted to receive a collection reservoir. The collection reservoir
has an open end and the end opposite the open end is closed. The
open end of the collection reservoir is adapted to receive the open
end of the dialysis reservoir. Thus, the open ends of both the
collection reservoir and the dialysis reservoir may be connected,
engaged, mounted or brought together, either by free positioning or
by screw mounting. The dialysis reservoir and the collection
reservoir are adapted or designed to be subjected to centrifugal
force by spinning in a centrifuge. Preferably, the collection
reservoir is shaped like a centrifuge tube.
[0007] The dialysis reservoir is secured in a floatation device and
floated in an appropriate dialysis buffer such that the dialysis
membrane of the dialysis reservoir is in contact with the dialysis
buffer. During dialysis, the collection reservoir may be either
mounted, engaged or positioned on the open end of the dialysis
reservoir or kept removed or separated from the open end of the
dialysis reservoir.
[0008] After dialysis is complete, the dialysis reservoir is
subjected to centrifugal force by positioning it in a centrifuge in
the orientation which allows centrifugal migration of the dialyzed
sample in the dialysis reservoir, through the open end of the
dialysis reservoir, into the collection reservoir. If the
collection reservoir was not positioned on the open end of the
dialysis reservoir during the dialysis then the collection
reservoir is positioned on the open end of dialysis reservoir prior
to centrifugation of the dialysis reservoir for collection of
dialyzed samples. The centrifugation allows the dialyzed sample in
the dialysis reservoir to migrate into the collection reservoir for
collection.
[0009] After collecting the dialyzed sample in the collection
reservoir, the sample may be stored in the collection reservoir
itself by placing a closure means on the open end of the collection
reservoir.
[0010] In an embodiment of the present invention, the dialysis
reservoir has outer and inner elements, wherein the outer element
sleeves over the inner element, sandwiching or securing a dialysis
membrane which forms the closed end opposite the open end of the
dialysis reservoir.
[0011] The depositing of the dialyzable samples into the dialysis
reservoir may be achieved either by directly depositing samples
into the dialysis reservoir or depositing the sample first into the
collection reservoir and then allowing the sample to migrate from
the collection reservoir to the dialysis reservoir, either by
inverting the open end of the collection reservoir into the open
end of the dialysis reservoir in which case the sample will migrate
under gravity into the dialysis reservoir or by centrifugation
force, i.e. centrifuging the collection reservoir. For collecting
the dialyzed sample after dialysis, the assembly of the dialysis
reservoir and the collection reservoir is spun in a centrifuge
which allows dialyzed sample to collect into the collection
reservoir.
[0012] The present invention also relates to a method of
fabricating a dialysis reservoir, a device for fabricating a
dialysis reservoir, a device for fabricating the dialysis reservoir
of the instant invention and a dialysis device of the instant
invention. The method of fabricating a dialysis reservoir
comprises: forming or providing a through-hole cap, having a
depending skirt so that the through-hole is defined by a narrowing
lip, the inside surface of the skirt being threaded; positioning a
gasket through the skirt so that it contacts the inside surface of
the lip; and fastening a dialysis membrane on the gasket.
[0013] A method of fabricating a dialysis reservoir comprises:
forming or providing a through-hole cap having a depending skirt so
that the through-hole is defined by a narrowing lip, the inside
surface of said skirt, preferably, being threaded; and positioning
a gasket having a dialysis membrane mounted within the gasket
through the skirt so that it contacts the inside surface of the
lip.
[0014] In an alternative embodiment, the method of fabricating a
dialysis reservoir comprises: forming or providing a through-hole
cap having a depending skirt so that the through-hole is defined by
a narrowing lip, the inside surface of said skirt, preferably,
being threaded; positioning a gasket through the skirt so that it
contacts the inside surface of the lip: and fastening a dialysis
membrane on the gasket. Preferably, the membrane is larger in
diameter that the gasket.
[0015] A device for fabricating a dialysis reservoir comprises: one
or more pillars, the pillar is provided to receive a gasket and a
dialysis membrane; a means to hold the dialysis membrane securely
in position on top of the pillar; and a means to engage a
through-hole cap on top of the pillar wherein the open end of the
through-hole cap sleeve over the pillar having the dialysis
membrane and the gasket so that the dialysis membrane contacts the
inside surface of the narrowing lip and closes the end opposite the
open end of the dialysis reservoir.
[0016] A device for fabricating a dialysis reservoir, comprising:
one or more pillars, the pillar is adapted to receive a gasket and
a dialysis membrane;
[0017] a means to position a sheet of dialysis membrane on top of
the pillar, the dialysis membrane is secured on the structure
surrounding the pillar;
[0018] a membrane cutting means to cut the dialysis membrane to
size and deposit on top of the pillar; and
[0019] a pressure means to hold the dialysis membrane securely in
position on top of the pillar and engage a through-hole cap defined
by a skirt and a narrowing lip on top of the pillar so that the
membrane contacts the inside surface of the narrowing lip.
[0020] The pillar has a diameter smaller than the open end of the
through-hole cap, defined by a circumferential lip and a skirt, so
that the cap sleeves freely over the pillar. The pillar may be
provided with a geometrical structure to allow the gasket to be
secured on top of the pillar. A sheet of dialysis membrane is
positioned on top of the pillar, preferably, the sheet of dialysis
membrane is held under tension on top of the pillar supported on
the surrounding structure. A membrane cutting die is lowered on the
membrane to cut the membrane to size and deposit the cut membrane
on top of the pillar. Preferably, the diameter of the membrane
cutting die is larger than the diameter of the gasket so that it
cuts a piece of membrane larger in diameter than the diameter of
the gasket.
[0021] Preferably, the means to hold the dialysis membrane securely
in position on top of the pillar is a pressure means, preferably, a
long pole like structure to put pressure on top of the membrane.
The pressure means long pole is lowered on top of the pillar,
sandwiching the membrane between the pole and the pillar.
[0022] After securing the dialysis membrane on top of the pillar, a
through-hole cap is engaged on top of the pillar, depositing the
assembly of the gasket and the membrane on the narrowing lip of the
cap, closing the end opposite the open end with a dialysis
membrane. The fabricated dialysis reservoir is removed from the top
of the pillar.
[0023] The device of the present invention can also be used for
assaying protein solutions containing agents that interfere with
protein assays. According to the present method, the protein sample
for assay will be deposited into the dialysis reservoir of the
present invention and dialyzed to remove interfering agents from
the protein solution. After dialysis, the device will be spun to
collect the protein solution in the collection reservoir.
[0024] In some assays dialysis may lead to a small increase in the
sample volume; the increase in the sample volume is determined by
determining the difference in the weight of the dialyzer,
containing sample, before and after dialysis. Reagents for protein
assay are introduced into the collection reservoir for reaction
with the protein solution collected in the collection reservoir.
The reaction product of the protein solution is subjected to an
optical density analyzer for the determination of protein
concentration. The optical density of the reaction product is then
compared with the optical density produced with a series of known
concentrations of protein solutions.
[0025] The device of the present invention is a closed system and
thus prevents loss of protein during dialysis and, subsequent to
dialysis allows one-hundred percent recovery of the protein.
Because there is no protein loss, the method can be used for
protein assays where dialysis is required prior to protein
assay.
[0026] The device of the present invention can also be used for
isolation of genomic DNA. One of the major problems associated with
isolation of high molecular weight genomic DNA is damage to DNA
during isolation-manipulation steps. The device of the present
invention can be used for isolating genomic DNA of high molecular
weight. According to the method, cellular nuclei is isolated by
grinding of cells and tissues using any popular method. The
isolated nuclei, tissue sample, or cells is transferred into the
dialysis reservoir of the present invention. The suspension of
nuclei or sample is subjected to proteolytic digestion in the
dialysis reservoir, preferably, using proteinase K, pepsin,
trypsin, etc. After proteolytic digestion, the suspension is
dialyzed in the dialysis reservoir. During dialysis small peptides
and other impurities are dialyzed away, leaving behind, in the
dialysis reservoir pure and high molecular weight genomic DNA.
Since, digestion of nuclei and dialysis do not involve physical
manipulation, the genomic DNA is protected from shear damage,
resulting in high molecular weight DNA product.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The invention is explained with the help of following
drawings:
[0028] FIG. 1 shows an embodiment of a dialysis reservoir, wherein
(a) is a top view and (b) shows a cross sectional view.
[0029] FIG. 2 shows an embodiment of a collection reservoir.
[0030] FIG. 3 shows various stages of assembly of the dialysis
reservoir of FIG. 1 and the collection reservoir of FIG. 2; 3(a)
shows a cross sectional view, 3(b) shows cross a sectional view
after assembly and 3(c) shows the front view of the assembled
dialysis reservoir and the collection reservoir.
[0031] FIG. 4 shows the assembled dialysis device of FIG. 3(c)
floated in a dialysis tank for dialysis.
[0032] FIG. 5 shows an alternative embodiment of the dialysis
reservoir, 5(a) shows a top view and 5(b) shows a side view.
[0033] FIG. 6 shows an alternative embodiment of the collection
reservoir.
[0034] FIG. 7 shows the assembly of the dialysis reservoir of FIG.
5 and the collection reservoir of FIG. 6.
[0035] FIG. 8. shows the dialysis reservoir of FIG. 5 floated in a
dialysis tank for dialysis.
[0036] FIG. 9. Shows an alternative embodiment of the dialysis
reservoir; 9(a) shows top view of the multifaceted dialysis
reservoir, 9(b) shows a cross sectional view showing outer and
inner elements of the dialysis reservoir and 9(c) shows the outer
element sleeving over the inner element.
[0037] FIG. 10. Shows the dialysis reservoir of FIG. 9 assembled
with the collection reservoir of FIG. 2.
[0038] FIG. 11 Shows a flotation device for floating the dialysis
reservoir.
[0039] FIG. 12 Shows a cross sectional view of the relative size of
a gasket and a dialysis membrane, wherein 12(a) shows that the
dialysis membrane is larger in diameter than the gasket and 12(b)
shows the edges of the dialysis membrane encircling the gasket.
[0040] FIG. 13 Shows elements of a device for fabricating a
dialysis reservoir, having a pillar and a surrounding structure and
a die for cutting a sheet of dialysis membrane to size and
depositing the cut membrane on top of the pillar.
[0041] FIG. 14(a) shows a top view of the pillar having flat top
surface, 14(b) shows a cross sectional view of an alternative
embodiment of the pillar having a geometrical structure to secure a
gasket on top of the pillar, and 14(c)a cross sectional view of a
dialysis membrane and a gasket positioned on top of the pillar.
[0042] FIG. 15 shows further elements of the device for fabricating
a dialysis reservoir, not shown in FIG. 13, having a means to hold
a membrane on top of the pillar and concurrently engaging a
through-hole cap on top of the pillar.
[0043] FIG. 16(a) shows a through-hole cap engaged on top of the
pillar to receive the assembly of the gasket and the membrane and
FIG. 16(b) shows a fabricated dialysis reservoir separated from the
pillar shown in FIG. 16(a).
PREFERRED EMBODIMENT OF THE INVENTION
[0044] In the embodiment of the invention shown in FIGS. 1-4, the
dialysis device is made of a dialysis reservoir 2 (FIG. 1) and a
collection reservoir 1 (FIG. 2). Preferably the dialysis reservoir
2 is a structure similar to a removable cap adapted with a dialysis
membrane on the end opposite to the open end of the cap. The
dialysis reservoir may be a cup shaped structure. The collection
reservoir 1 is preferably shaped as a centrifuge tube. The open end
of the dialysis reservoir 2 can be positioned on the open end of
the collection reservoir 1.
[0045] The dialysis reservoir 2, as shown, has an open end 5 and an
end opposite the open end. The end opposite the open end is closed
with at least a dialysis membrane 3. The collection reservoir 1 has
an open end 6 and an elongated body and an end 19 opposite the open
end which is closed. The structure defines an elongated hollow
area.. Both the dialysis reservoir and the collection reservoir are
provided with cooperating screw threads 7 so that, for instance,
the open end of the dialysis reservoir 2 can be mounted or
positioned on the open end of the collection reservoir 1, by
screwing the two together.
[0046] In the dialysis reservoir 2, the end opposite the open end 5
has a circumferential lip 12 defining through bore 20. Connected to
narrow lip 12 is a circumferential skirt member 14 creating joint
16, and positioned on the inside surfaces of the skirt are threads
7.
[0047] In fabrication, a dialysis membrane 3 is positioned through
the open end 5 and positioned or centered to cover through-bore 20.
In this manner the outer edge surfaces are defined by
circumferential lip 12. Preferably positioned between a top surface
of the dialysis membrane 3, and the inner surface of the narrowing
lip 12 is a gasket 4. Thus, gasket 4 is placed near the surface of
joint 16 and is simultaneously in contact with membrane 3. When the
collection reservoir 1 is positioned on the open end of the
dialysis reservoir 2, by screwing, as shown in FIG. 3(a) and in
FIG. 3(b), the open end of the collection reservoir 1 presses
against the gasket 4 and the membrane 3 making a leak proof seal
between the membrane and the open end of the collection
reservoir.
[0048] Preferably, the dialysis membrane 3 is larger in diameter
than the gasket 4, as shown in FIG. 12(a). The dialysis membrane
having a diameter larger than the diameter of the gasket allows the
membrane to completely surround the gasket, consequently the gasket
4 resides within a nest created by the membrane 3, as shown in FIG.
12(b). Preferably, the dialysis membrane and the gasket may be
fused or glued together so that they behave as a single integral
item. In addition, the dialysis membrane forming the closed end
opposite the open end of the dialysis reservoir may be fused into
the body of the dialysis reservoir as an integral part.
Alternatively, membrane and gasket may be manufacture by a process
which allows creation of a gasket on the membrane itself
[0049] In an alternative embodiment of the dialysis reservoir, as
shown in cross section in FIG. 9, the dialysis reservoir 13 is made
of an outer element 9 and an inner element 10. The outer element 9
is designed to sleeve over or telescopically receive the inner
element 10 and the two pieces fit tightly or snugly together.
Preferably, the outer 9 and the inner elements 10 are provided with
a self locking structure to lock them relative to one another such
as a bayonet mount (not shown in drawings). Alternatively, the
outer element 9 and inner elements 10 are provided with a geometric
structure to prevent the rotation of the outer element relative to
the inner element or vice-versa. In a preferred embodiment, the
outer and inner elements are multifaceted, as shown in FIG. 9,
which shows the dialysis reservoir 13 with six sides. Other
physical features such as uneven or gripping surface can also be
provided on the outer and inner elements to prevent the rotation of
the outer element relative to the inner element. In the outer
element 9, the end opposite the open end 5 has a flange
(circumferential lip) 12 which prevents the inner element 10 from
passing through the outer element 9. The inner element 10 has a
through bore which is aligned with through-bore 20 of the outer
element and the inside face of element 10 is provided with screw
threads 7 for mounting the dialysis reservoir 13 on the collection
reservoir 1. For assembling the outer and inner elements into a
dialysis reservoir 13, a dialysis membrane 3 is placed between the
two elements, a gasket 4 may also be placed on the membrane 3 on
the side nearer to the open end 5, the inner element 10 is pushed
into the outer element 9 which sandwiches the dialysis membrane 3
and gasket 4 between the two elements, as shown in FIGS. 9(b) and
9(c). The circumferential lip 12 prevents the inner element 10 from
passing through the outer element 9. The self locking structure as
described above will lock the inner element in position and make a
tight leak proof seal against the gasket and the membrane (not
shown in Figs.). Alternatively, when the open end of assembled
dialysis reservoir 13 is positioned, by screwing, on the open end
of the collection reservoir 1, the open end of the collection
reservoir presses against the gasket 4 and the membrane 3 and makes
a tight seal, as shown in FIG. 10.
[0050] In use for dialysis, a liquid sample is placed inside the
hollow of the collection reservoir 1. The dialysis reservoir,
defined by the circumferential lip and skirt (either reservoir 2 or
13) is secured onto collection reservoir 1, as shown in FIGS. 3
& FIG. 10. The dialysis device, the dialysis reservoir and
collection reservoir assembly as shown in FIG. 3(c) and FIG. 10, is
inverted and mounted on a doughnut-shaped floatation device 22 (see
FIG. 11), as shown in FIG. 4, and placed in a dialysis tank 17
(FIG. 4 and FIG. 8) containing the appropriate dialysis buffer 18.
The floatation device 22 receives the dialysis reservoir via hole
21. The dialysis membrane 3 in the dialysis reservoir contacts the
dialysis buffer. When the collection reservoir is inverted, the
liquid sample inside the collection reservoir migrates into the
dialysis reservoir and rests on the dialysis membrane 3. The
dialysis buffer is stirred during dialysis. Salts and other
molecules within the dialysis reservoir migrate across the membrane
3 until an equilibrium is reached with the dialysis buffer in the
dialysis tank. After the completion of dialysis process, the device
assembly is removed from the floatation device 22. The collection
reservoir is placed in a centrifuge and spun for a brief 5-10
seconds to collect the dialyzed sample in the bottom of the
collection reservoir 1. Sample collection by centrifugation allows
100% recovery of the samples in the collection reservoir. After
collecting the sample in the collection reservoir, the dialysis
reservoir may be replaced with a closure means i.e., a cap for
storage of the dialyzed sample in the collection reservoir for a
later use.
[0051] In an alternative embodiment of the invention, the dialysis
reservoir is made of a cup shaped structure 15 as shown in FIG. 5.
The dialysis reservoir has an open end 5 and the end opposite the
open end is closed with a dialysis membrane 3. The collection
reservoir 8 (FIGS. 6 and 7) has an open end 6 and an end 19
opposite the open end is closed. Preferably, the collection
reservoir 8 is a centrifuge tube, FIG. 6. The dialysis reservoir
has a shoulder 14 which assists positioning of the open end of the
dialysis reservoir 15 into the open end of the collection reservoir
8. The open end of the dialysis reservoir 15 is freely suspended
into the open end of the collection reservoir 8, the dialysis
reservoir rest on the shoulder 14 into the open end of the
collection reservoir 8, as shown in FIG. 7. Shoulder 14 may also be
provided to the open end of the collection reservoir to allow
positioning of the open end of the dialysis reservoir.
[0052] For dialysis, a sample is placed into the dialysis reservoir
2 or 13 (FIG. 9c) and secured on the float 22 and floated in a
dialysis tank 17 shown in FIG. 8, such that the membrane contacts
the dialysis buffer. After dialysis is complete, the open end 5 of
the dialysis reservoir 15 is assembled with the open end 6 of the
collection reservoir 8, as shown in FIG. 7 and the whole assembly
is spun for collection of the sample into the collection reservoir
8. After spinning, the dialysis reservoir 15 is disassembled from
the collection reservoir 8 in order to reach the sample collected
in the collection reservoir. The dialyzed sample may be stored in
the collection reservoir by placing a closure means on the open end
6 of the collection reservoir 8. The dialysis device 13 of FIG. 9
could also be use as described in this paragraph.
[0053] FIG. 13 shows elements of the device for fabricating a
dialysis reservoir. The device is provided with one or more pillar
like structures 23 (FIG. 14a) and defined by a circumferential
depending hollow 40 and a surrounding pillar support structure 24.
The diameter of a pillar 23 is smaller than the open end of the
dialysis reservoir, so that the pillar may freely pass through the
end of the dialysis reservoir (a through-hole cap, defined by the
circumferential lip and skirt). Preferably, the top of the pillar
has a flat surface. The top of the pillar may be provided with a
geometrical structure 25 to secure a gasket on top of the pillar,
as shown in FIGS. 13 and 14(b). Structure 25 has a circular
elevation having a diameter that allows the gasket 4 to seat on the
elevation and is prevented from side-ways movement. See FIG. 14(b).
The fabricating device preferably has an array of pillars to
facilitate mass production.
[0054] In fabricating a dialysis reservoir a gasket 4 (FIG. 13) is
positioned on top of the pillar and a sheet or a section of a
dialysis membrane 3 is positioned on the pillar 23. The membrane 3
is secured to the top of the pillar 23 by applying a pressure
devices on top of the membrane, which is supported on the
surrounding structure 24. The pressure device is a plate 27 having
a hollow middle section an having an O-ring 26 fastened to the
under-face of the plate near the inner circumferential surface 42
of the plate. When the plate is lowered on top of the membrane, the
O-ring puts downward pressure on the membrane supported on the
surrounding structure 24 as described above, and secures the
membrane in place on top of the pillar 23. The membrane can be cut
to size and deposited on top of the pillar by lowering a membrane
cutting die, having cutting edges or teeth 29 as shown. As die 28
is lowered on top of the membrane 3 (as shown by the arrow), a
circular piece of membrane is cut and deposited on top of pillar 23
(FIG. 14(c)).
[0055] Alternatively, the gasket 4 may be fabricated to possess a
pre-mounted dialysis membrane 3 within the gasket. In such a case,
it would not be necessary to place a sheet or section of membrane
on top of the gasket and cut to size with die 28. Instead the
gasket possessing such a membrane would be placed on top of the
pillar.
[0056] FIG. 15 shows further elements of the device for fabricating
a dialysis reservoir. After a membrane and a gasket is deposited on
top of pillar 23, a through-hole cap 2, defined by a
circumferential lip and a skirt, is deposited on top of the
membrane and the gasket. The open end 5 of the cap is near the top
of the pillar. The cap 2 is engaged on top of the pillar by holding
the membrane securely in position with a pushing element 46.
Pushing element 46 is composed of spring piston 30 and push arms
31. The spring piston 30 and push arms 31 are connected to common
pushing element 46 as shown. Spring 33 of spring piston 30 allows
the spring piston 30 to exert a downward pressure on the membrane 3
(in the direction of the arrows) and concurrently allows the
push-arm 31 to move downward (as the spring depresses) and push the
cap so that is sleeves over the pillar, depositing the membrane and
gasket on the circumferential lip 12 of the cap as shown in FIG.
16(a). The depending skirt of the reservoir is received within
circumferential hollow 40. After assembly is completed the dialysis
reservoir is separated from the pillar 23 as shown in FIG.
16(b).
[0057] For simplicity, the device of FIG. 13 and FIG. 15 are shown
separately, however, in fact the device can be and is constructed
with elements to work cooperatively to facilitate the reservoir as
above described:
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