Chemistry: molecular biology and microbiology – Treatment of micro-organisms or enzymes with electrical or... – Cell membrane or cell surface is target
Reexamination Certificate
1998-11-12
2001-09-11
Tate, Christopher R. (Department: 1651)
Chemistry: molecular biology and microbiology
Treatment of micro-organisms or enzymes with electrical or...
Cell membrane or cell surface is target
C435S173100, C435S306100, C204S194000, C204S280000, C204S600000
Reexamination Certificate
active
06287831
ABSTRACT:
BACKGROUND
It is known that an electrical field can be used to manipulate cells. Electrical manipulation of cells can be used for separating cells, holding cells, killing micro-organisms, or other operations.
Electrical manipulation of a cell is based on dielectrophoresis. A neutral particle, such as a microbial cell, will become polarized when subjected to a non-uniform electric field. Due to the non-uniformity of the field, a net force will act on the particle. This force will produce movement of the suspended cell. This phenomenon known as dielectrophoresis. the inside of the cell has and holds a different charge than the outside of the cell.
Macro sized electroporation systems have been designed for injecting genes into cells. See, “Electroporation and Electrofusion in Cell Biology,” E. Newman, A. E. Sauer, C. A. Jordan, ed. Plenum Press, N.Y. 1989. These systems often use electrical fields to make microsized pores on cell membranes.
Cell lysis typically refers to opening a cell membrane to allow the cell interior to come out. Cell lysing can be used to obtain intracellular material for further analysis such as DNA identification.
It is known to use the science of micromachining to manipulate cells. See, for example, S. Lee, “A Study of Fabrication and Applications of Micromachined Cell Manipulating Devices,” Ph.D. Thesis, Seoul National University, pp. 77-81, 1996. However, no one has previously reported using micromachining to form a device for cell lysis. Usually, these systems use cuvets that have a few millimeter range electrode gap. Lysing cells with this kind of size requires a few kilovolts of voltage source across such a gap.
Prior cell lysing has been reported using pulsed electric fields in a macrosized electroporation system. See, for example, T. Grahl and H. Markl, “Killing of Microorganisms by Pulsed Electric Fields,” Appl. Microbio. Biotechnol., 45, pp. 148-157, 1996. The disadvantages of such a macrosized device have been described above.
J. Cheng, et al, “Preparation and Hybridization analysis of DNA/RNA from
E. Coli
on Microfabriacted Bioelectronic Chips” has suggested electronic cell lysis on a chip. However, this system still required hundreds of volts for lysing the cell.
SUMMARY
The present disclosure describes a new micromachined cell lysis device. A microsized cell lysis device as disclosed reduces the size of the entire system including the power source, since the electrode gap could be reduced to a few &mgr;m or smaller. This micro-sized cell lysis device is capable of operating on a small number of cells due to its small size.
A special way of using the electric field that can greatly simplify the purification steps is described. This can be used to prepare biosamples. In addition, the small size allows a reduction in voltage required for lysing. The voltage can be reduced to practical levels, e.g., less than 50 volts, since the electrode gap is on the order of microns.
A new structure is also described for cell lysis.
REFERENCES:
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patent: 4971910 (1990-11-01), Zimmermann
patent: 4975175 (1990-12-01), Karube et al.
patent: 5491097 (1996-02-01), Ribi et al.
Cheng et al. Nature Biotechnology vol. 16, pp. 541-546, Jun. 1998.
Lee Sang-Wook
Tai Yu-Chong
California Institute of Technology
Fish & Richardson P.C.
Tate Christopher R.
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