GEL CASSETTE OPENER

Gel cassette opening devices and methods for opening gel cassettes are provided.

BACKGROUND OF THE INVENTION

Western blotting is widely used technique for protein analysis. In the technique, proteins are separated by gel electrophoresis, are transferred onto a hydrophobic membrane and are then visualized using various labeling method.

To perform western blot analysis of protein bands separated by gel electrophoresis, the user manually opens the gel cassette, gently lifts the fragile gel and places the gel on a blotting membrane. During the process of placing the gel on the blotting membrane, the gel may be damaged by tearing, warping, and/or stretching. Once the gel is placed on the membrane, the user gently aligns the gel with the membrane edges. The user then places the membrane with the gel in the western blotting apparatus for the transfer step. Thus, manual removal of the gel from the cassette and placement of the gel on the membrane without damaging the gel is challenging and requires a practiced user with technical skill.

BRIEF SUMMARY OF THE INVENTION

Provided herein are devices for opening gel cassette and methods of using such devices.

In an embodiment, a gel cassette opener comprises a drawer slidably mounted in a housing and movable in a sliding direction between a first position in which at least a portion of the drawer extends outside a front opening of the housing, and a second position in which the drawer is contained within the housing, wherein the drawer comprises two elongated support rails for supporting a gel cassette and a membrane in a horizontal side-by-side position; a first and second vacuum chuck movably mounted in the housing, each chuck comprising a planar support having a vacuum aperture and a fluid aperture, wherein the first vacuum chuck is located below the plane of the drawer and the second vacuum chuck is located above the plane of the drawer; a vacuum source operably connected to the vacuum aperture in each of the vacuum chucks; a fluid (e.g., air, nitrogen, water, or oil) source operably connected to the fluid aperture in each of the vacuum chucks; and control circuitry for controlling operation of the gel cassette opener.

In some embodiments, the gel cassette opener further comprises a third vacuum chuck located below the plane of the drawer and movably mounted within the housing. In some embodiments, the gel cassette opener further comprises a fourth vacuum chuck located above the plane of the drawer and movably mounted within the housing. In certain embodiments, the fourth vacuum chuck comprises a recess sized such that the margins of the gel rest outside the recess when the gel is vacuum gripped by the fourth vacuum chuck. In certain embodiments, the margins are about 1-5 millimeters wide. In some embodiments, the recess has a depth of about 0.25-0.75 millimeters. In some embodiments, the recess has a depth of about 0.5 millimeters. In some embodiments, the first, second, third and/or fourth vacuum chucks are moveable in an X, Y, and/or Z direction. In certain embodiments, the vacuum source is connected to the vacuum aperture by a vacuum channel within each of the vacuum chucks. In some embodiments, the air or water source is connected to the air aperture by an air channel within each of the vacuum chucks.

In an embodiment, a method of opening a gel cassette comprises providing a gel cassette comprising a gel sandwiched in between an upper wall and a lower wall; removing the gel from the upper wall while supporting the gel with the lower wall; and vacuum gripping an exposed side of the gel while removing the gel from the lower wall. In some embodiments, the method further comprises moving the gel to a position above a membrane and placing the gel on the membrane. In some embodiments, the gel is removed from the upper wall by injecting a fluid (e.g., air, nitrogen, water, or oil) through a first hole in the upper wall. In some embodiments, the gel is removed from the lower wall by injecting the fluid through a second hole in the lower wall.

In some embodiments, the method of opening a gel cassette comprises providing a gel cassette comprising a gel sandwiched in between a lower wall and an upper wall; removing the gel from the lower wall while supporting the gel with the upper wall; mating an exposed side of the gel to a membrane; and removing the gel from the upper wall while the gel remains mated to the membrane. In some embodiments, the gel is removed from the lower wall by injecting a fluid through a second hole in the lower wall. In certain embodiments, the gel is removed from the upper wall by injecting the fluid through a first hole in the upper wall. In some embodiments, the method further comprises applying a vacuum to the gel from below while injecting the fluid through the first hole in the upper wall.

In certain embodiments, a plug is removed from the first hole and the second hole prior to injecting fluid through each of the first and second holes. In some embodiments, the first hole is located substantially in the center of the upper wall and the second hole is located substantially in the center of the lower wall. In some embodiments, the membrane is attached to a frame. In some embodiments, the frame comprises raised sharp inner edges that cut through the gel when pressed against the gel. In certain embodiments, the upper or lower wall of the gel cassette comprises a groove on an inner surface contacting the gel and the groove runs in a continuous line parallel to the edges of the upper or lower wall. In some embodiments, the upper and lower walls are not attached to each other.

DETAILED DESCRIPTION OF THE INVENTION

Described herein are automated gel cassette openers and methods of using such devices. Gel cassette openers have been discovered that are “hands-off” and automatically remove each wall of the gel cassette while supporting the delicate gel. The cassette opener can be used as a stand-alone system or as part of a western blotting work flow.

As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used herein, the term “about” refers to the recited number and any value within 10% of the recited number. Thus, “about 5” refers to any value between 4.5 and 5.5, including 4.5 and 5.5.

FIGS. 1-5Iillustrate embodiments of devices for opening gel cassettes. In an embodiment, a gel cassette opener100,200,300comprises a drawer102,202,302slidably mounted in a housing and movable in a sliding direction between a first position in which at least a portion of the drawer extends outside a front opening of the housing, and a second position in which the drawer is contained within the housing. The drawer102,202,302comprises two elongated support rails104,204,304for supporting a gel cassette106,206,306and a membrane108,208,308in a horizontal side-by-side position. The opener100,200,300also comprises at least two vacuum chucks movably mounted in the housing. Each chuck comprises a planar support having a vacuum aperture110,210,310and a fluid aperture112,212,312. In an embodiment, a first vacuum chuck114,214,314is located below the plane of the drawer and a second vacuum chuck116,216,316is located above the plane of the drawer (FIGS. 5A-5I). In certain embodiments, the cassette opener further comprises a third vacuum chuck118,218located below the plane of the drawer and movably mounted within the housing (FIGS. 2E-4K). In some embodiments, the cassette opener further comprises a fourth vacuum chuck120located above the plane of the drawer and movably mounted within the housing (FIGS. 1-2N).

A vacuum source is operably connected to the vacuum aperture110,210,310in each of the vacuum chucks. In some embodiments, the vacuum source is connected to the vacuum aperture by a vacuum channel122,222,322within each of the vacuum chucks. In certain embodiments, the vacuum channel runs from an upper surface of the vacuum chuck to a lower surface of the vacuum chuck. A fluid (e.g., air, nitrogen, water, or oil) source is also operably connected to the fluid aperture112,212,312in one or more of the vacuum chucks. In some embodiments, the fluid source is connected to the fluid aperture112,212,312by a fluid channel124,224,324within one or more of the vacuum chucks. In some embodiments, the fluid channel runs from the upper surface to the lower surface of the vacuum chuck. The vacuum source and the fluid source can be connected to the chucks by, for example, flexible tubing and can be controlled by valves. The cassette opener also has control circuitry for controlling operation of the gel cassette opener.

In some embodiments, the first and second vacuum chucks comprise an inner o-ring126,226,326and an outer o-ring127,227,327each sitting in a depression on the surface of the chuck that contacts a cassette wall. The o-rings mate with the cassette wall. The area between the inner and outer o-rings is vacuumed to grip the wall. The area inside the inner o-ring126,226,326is pressurized to inject fluid through the hole in the cassette wall to separate the gel from the wall. In some embodiments, other types of elastic seals (e.g., bellow suction caps or vacuum pads) can be used instead of o-rings to facilitate gripping an uneven surface.

In certain embodiments, the third chuck118,218comprises raised edges that mate with the membrane and press against the edges of the gel. Referring toFIGS. 2EandFIG. 3, the third chuck can also have grooves128,228on the surface that mate with the membrane108,208. The grooves128,228can be in any pattern (e.g., squares, circles, etc.). The grooves128,228are connected to the vacuum aperture and assist in applying vacuum evenly across the membrane. In some embodiments, the grooves128,228run along the perimeter of the third chuck118,218upper surface and intersect through the middle of the upper surface.

In embodiments of the cassette opener having a fourth vacuum chuck120, the fourth vacuum chuck120can comprise a recess130sized such that the margins of the gel rest outside the recess when the fourth vacuum chuck is vacuum gripping the gel (FIG. 6). In certain embodiments, the recess is sized such that margins about 1-5 millimeter wide rests outside the recess when the fourth vacuum chuck is vacuum gripping the gel. In some embodiments, the recess130has a depth of about 0.25-0.75 millimeters. In certain embodiments, the recess has a depth of about 0.5 millimeters.

In some embodiments, the first, second, third and/or fourth vacuum chucks can move in an X, Y, and/or Z direction. In some embodiments, one or more vacuum chucks located below the plane of the drawer can move in the Z direction and one or more vacuum chucks located above the plane of the drawer can move in the X direction (FIGS. 1-4I). In certain embodiments, the vacuum chucks can move in the X and Z direction (FIGS. 5A-5I).

In some embodiments, the vacuum chucks are each driven by a motor132,232(FIGS. 1-4K). In embodiments in which two vacuum chucks are positioned above and/or below the plane of the drawer, the vacuum chucks can move together or independently.

The drawer of the cassette opener100,200,300can be sized to hold a single mini or midi-sized gel cassette and membrane.

Provided are methods of opening gel cassettes using the devices described herein. In an embodiment, the method comprises providing a gel cassette comprising a gel134,234,334sandwiched in between an upper wall136,236,336and a lower wall138,238,338. In some embodiments, the lower and upper walls of the cassette are not attached to each other. In certain embodiments, the lower and upper walls are sealed with a face seal and external clips that hold the two walls together. The upper wall136,236,336of the cassette has a first hole140,240,340therein and the lower wall138,238,338has a second hole142,242,342therein. In some embodiments, the first and second holes are located substantially in the center of the first and second walls, respectively (FIGS. 7A-7C). Each hole can be plugged with a removable plug144(FIG. 8). The plugs are removed prior to opening the cassette. Also prior to opening the cassette, the gel134,234,334is subject to polyacrylamide gel electrophoresis which separates biological molecules (e.g., proteins or nucleic acids) into bands based on their electrophoretic mobility. The electrophoretic mobility is a function of molecular weight, charge, and conformation of the molecule.

In certain embodiments, the lower or upper wall of the gel cassette comprises a shallow groove146on an inner surface contacting the gel and the groove146runs in a continuous line parallel to the edges of the lower or upper wall (FIG. 9). In some embodiments, the groove146is about 0.1-1 millimeters in depth. In some embodiments, the groove146is about 0.5 millimeters in depth. During casting of the gel, the gel fills this groove, creating a ridge148in the gel. The ridge148in the gel acts as an obstruction to air flow such that when air is injected through a hole in the wall, the air spreads over substantially the entire area of the gel before leaking out through the edges. This facilitates the separation of the gel from the cassette wall.

In some embodiments, the gel cassette106,206,306and a western blotting membrane108,208,308are placed in a horizontal side-by-side position on rails in a drawer102,202(FIGS. 2A, 4A) and the drawer102,202,302is inserted into the housing of the cassette opener100,200,300such that at least one vacuum chuck is positioned above and below the cassette106,206,306(FIGS. 2A-2F, 4B-4D, 5A).

Next, a first vacuum chuck114,214,314underneath the plane of the drawer102,202,302is moved up in the Z direction, mates with the lower wall of the cassette, and pushes the cassette toward the second vacuum chuck116,216,316(FIGS. 2G, 4E, 5B). In embodiments in which the first and second vacuum chucks have an inner O-ring126,226,326and an outer O-ring127,227,327, the inner0-ring126,226,326in the first and second vacuum chucks forms a seal around the first and second holes in the respective upper and lower walls of the cassette. In embodiments having a third vacuum chuck118,218below the plane of the drawer and in a side-by-side relationship with the first vacuum chuck (FIGS. 2G, 4E), both the first vacuum chuck114,214and the third vacuum chuck118,218are moved together such that when the first vacuum chuck114,214is moved up, the third vacuum chuck118,218is also moved up.

The next step of the method comprises removing one of the walls of the cassette while supporting the gel with the remaining wall.

In an embodiment having four vacuum chucks (FIG. 2H), the gel134is first removed from the upper wall136by using the second vacuum chuck116above the plane of the drawer to inject fluid through the first hole140in the upper wall136of the cassette while supporting the gel134with the lower wall138. In some embodiments, while the second vacuum chuck116is injecting fluid through the first hole140, the first vacuum chuck114can apply a vacuum to the lower wall138of the cassette to aid in gel removal. Next, the second and fourth vacuum chucks116,120located above the plane of the drawer move to the left. The second vacuum chuck116holds the upper wall136of the cassette by vacuum and the fourth vacuum chuck120is positioned over the gel134(FIG. 2I). The next step of the method comprises vacuum gripping an exposed side of the gel134with the fourth vacuum chuck120while injecting fluid through the second hole142in the lower wall138with the first vacuum chuck114to remove the gel134from the lower wall138(FIGS. 2J-2K). In some embodiments, the gel134is vacuum gripped in a recess130in the fourth vacuum chuck120. The gel134is then moved by the fourth vacuum chuck120to a position above the membrane108(FIG. 2L) and the second vacuum chuck116that is vacuum-gripping the upper wall136moves over the lower wall138resting on the drawer rails. The first vacuum chuck114and a third vacuum chuck118below the membrane108are moved up so that the first vacuum chuck114is supporting the lower wall138and the membrane108is positioned directly below the gel134(FIG. 2M). The vacuum in the second and fourth vacuum chucks116,120is then turned off so that the upper wall136of the cassette is placed on the lower wall138and the gel134is placed on the membrane108(FIG. 2N). The membrane108with the gel134thereon can then be removed from the cassette opener100for further processing (e.g., for western blotting) by ejecting the drawer from the housing of the cassette opener. The lower and upper walls136,138of the cassette can also be discarded.

In embodiments having two vacuum chucks (FIGS. 5A-5I) or three vacuum chucks (FIGS. 3-4K), the first vacuum chuck214,314is moved up in the Z direction to press against the lower wall238,338of the cassette and to vacuum grip the lower wall238,338while the second vacuum chuck216,316vacuum grips the upper wall236,336of the cassette. The gel234,334is then removed from the lower wall238,338by injecting fluid with the first vacuum chuck214,314through the second hole242,342in the lower wall238,338of the cassette (FIGS. 4F, 5C). The next step of the method comprises moving the second vacuum chuck216,316to a position above the membrane208,308(FIG. 4G, 5D) while the second vacuum chuck216,316is vacuum gripping the upper wall236,336that has the gel thereon. In some embodiments, a third vacuum chuck218below the membrane208is moved up so that the membrane208is mated with the gel234(FIG. 4H). In certain embodiments, the second vacuum chuck316moves down to the membrane308until an exposed side of the gel334is mated with the membrane308(FIG. 5E). In some embodiments in which the membrane is mounted to a frame that has raised sharp inner edges (FIG. 10), the sharp edges cut the gel as the membrane is mated with the gel (FIGS. 11A-11B). The gel234,334is then released from the upper wall236,336and is placed onto the membrane208,308by using the second vacuum chuck216,316to inject fluid through the first hole240,340in the upper wall236,336of the cassette (FIGS. 4I, 5E). As the gel234,334is released from the upper wall236,336, the upper wall236,336remains vacuum gripped by the second vacuum chuck216,316. The upper wall236,336is moved to the left by the second vacuum chuck216,316so that the upper wall236,336is positioned above the lower wall238,338resting on the drawer rails (FIGS. 4J, 5F-5G). In some embodiments (FIG. 5H), the second vacuum chuck316moves down in the Z direction until it is close to the lower wall338. The vacuum in the second vacuum chuck216,316is then turned off to release the upper wall236,336so that the upper wall236,336rests on the lower wall238,338(FIGS. 4K, 5I). The cassette walls can then be discarded and the membrane with the gel thereon can then be removed from the cassette opener for further processing. In some embodiments, the drawer is ejected from the housing of the cassette opener100so that the cassette walls and the membrane with the gel thereon can be removed from the drawer.

All patents, patent applications, and other published reference materials cited in this specification are hereby incorporated herein by reference in their entirety.