Agitating – Stirrer within stationary mixing chamber – Magnetic stirrer
Reexamination Certificate
1998-01-15
2001-06-19
Reifsnyder, David A. (Department: 1723)
Agitating
Stirrer within stationary mixing chamber
Magnetic stirrer
C366S273000, C366S241000, C220S212500, C210S321600, C210S321630
Reexamination Certificate
active
06247840
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable
STATEMENT REAGARDING FEDERALLY FUNDED RESEARCH OR DEVELOPMENT
Not applicable
REFERENCE TO MICROFICHE APPENDIX
Not applicable
BACKGROUND OF THE INVENTION
The Revolutionary Dialysis Container specifically relates to dialysis of biological samples in biochemical and immunochemical studies.
In biochemical processes such as extraction, purification, conjugation and characterization, excess reagents are removed from desired molecules by dialysis. To perform dialysis a sample is taken in a bag with semipermeable membrane and stirred against buffer present in a large container. With time large molecules are retained inside the bag while small reagent molecules go out into buffer surrounding the bag. During dialysis, buffer is changed several times so that undesired molecules along with buffer are removed. Routinely, glass or plastic beakers are used to hold buffer. The first problem with these oversized containers is lack of proper grip. A slip causes loss of valuable sample, spill of reagents and breakage of the container. The second problem is in mixing buffer. Theoretically, fast mixing results in quick exchange of chemicals across the membrane. But, in practice, when buffer is mixed, a vortex develops and makes dialysis bag dive to bottom where either the bag pushes magnet go out of spin or magnet damages the membrane of bag. Also, some samples due to the presence of high amount of salt automatically sink to bottom and face similar consequences. These events not only impair dialysis but also result in total or partial loss of valuable sample. The third problem is in exchange of used buffer with fresh. Ordinarily, used buffer is poured out from the wide mouth of beaker. Dialysis bag and spin magnet often slip into sink and get contaminated with undesirable chemicals and materials. In other instances when samples contain radioactivity, therapeutic drugs or toxins, it is undesirable to touch or contaminate other surfaces. Therefore, there is a need for a better dialysis container.
Shibora in U.S. Pat. No. 5,141,327 describes a stirrer that includes a stator and a housing containing a rotor. The rotor is a hollow cylinder with openings at both ends and with slots in the center. The liquid which flows in through two communication ports of housing is sucked into the rotating rotor, mixed and returned through slots of rotor to the container through an additional port present in the center at the top of housing. This configuration has no mechanism to prevent dialysis bags of different diameters and lengths either blocking the ports or getting sucked into housing and then, into the rotating cylindrical rotor. Therefore, the dialysis bags may block the flow of liquid, may get ruptured by the rotor or may stop the motion of rotor itself. The unit is bulky and needs maintenance.
Hyden in U.S. Pat. No. 4,192,748 describes a dialysis apparatus where a long dialysis membrane forms a partition between a sample to be dialyzed and the buffer to be used in dialysis. This apparatus which has several peripheral equipment, is expensive, bulky, and requires extensive maintenance. It is highly suitable for patient care. For instance, blood is continuously pumped into apparatus to remove unwanted chemicals and the dialyzed blood is then returned to the body of patient.
Shukla in U.S. Pat. No. 5,733,442 describes a microdialysis system for the dialysis of microliter volume of biological materials. However, this system is not convenient for samples of higher volumes (several milliliters to deciliters). Placing a small magnet inside the chamber is cumbersome and inefficient for rapid stirring. Also, the magnet does not stir outside buffer surrounding the dialysis system. Besides, the area of membrane, and therefore the volume of sample, exposed for dialysis is small when compared to the area of an entire bag exposed to buffer. Hence, the microdialysis system takes a lot longer time to complete dialysis of samples.
OBJECTS AND ADVANTAGES
The objects and advantages of the Revolutionary Dialysis Container are:
(a) to provide in the buffer reservoir, a flat top plate and a vertical side wall (together called as Sample Saver) which irrespective of the speed of mixing prevent physical contact between delicate dialysis bag and highly spinning bar magnet;
(b) to provide apertures in the flat top plate and in the vertical side wall so that only buffer circulates but dialysis bag do not percolate;
(c) to distribute holes in the flat top plate away from its center so that formation of vortex in buffer is suppressed, and
(d) to provide a handle, which has a wide top and which is separated from buffer reservoir by a large gap, so that a human can carry the unit with a non-slippery grip.
Further objects and advantages will be apparent from the following description and drawings.
BRIEF SUMMARY OF THE INVENTION
The Revolutionary Dialysis Container, with a built in handle and Sample Saver, is useful for safe dialysis of research biological materials. The side handle can be used by a research worker to lift and carry the unit and its contents with a firm grip. Sample Saver, a special device with a flat top plate and a vertical side wall, which is located inside the dialysis container, prevents physical contact between highly spinning bar magnet and delicate dialysis bag. However, it allows rapid mixing of buffer at all speeds of the enclosed bar magnet. Sample Saver, because of special spacial arrangement of apertures in its flat top plate, suppresses vortex formation in the buffer of container. Long dialysis bags safely rest on the flat top plate of Sample Saver.
REFERENCES:
patent: 4192748 (1980-03-01), Hyden
patent: 5141327 (1992-08-01), Shiobara
patent: 5733442 (1998-03-01), Shukla
Gaffar Shaik A.
Reifsnyder David A.
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