Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – By sudden release of pressure
Reexamination Certificate
2001-08-07
2004-02-24
McKane, Elizabeth (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
By sudden release of pressure
C435S236000
Reexamination Certificate
active
06696019
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to methods for sterilizing materials and preparing vaccines.
Various methods and devices exist for the sterilization, decontamination, or disinfection of biological and non-biological materials. These methods include thermal destruction (e.g., burning), heat sterilization, irradiation (e.g., ultraviolet or ionizing irradiation), gas sterilization (e.g., using ethylene oxide), photosensitization, membrane sterilization, or the use of chemical disinfectants (formaldehyde, glutaraldehyde, alcohols, mercury compounds, quaternary ammonium compounds, halogenated compounds, solvent/detergent systems, or peroxides).
Heat sterilization (e.g., autoclaving) is often used, for example, for sterilizing medical solutions prior to use in a patient. Heat sterilization typically requires heating a solution to 121° C. for a minimum of 15 minutes under pressure in an autoclave, maintaining the heat and pressure conditions for a period of time sufficient to kill bacteria, fungi, and protists and inactivate viruses in the solution.
Many reusable medical articles and materials are not suitable for disinfection or sterilization in an autoclave. For example, plastic parts on medical devices, hemodialyzers, and fiber optic devices are commonly sterilized by chemical germicide treatment. In general, germicides require several hours of treatment for the inactivation of microorganisms.
To ensure sterility in pharmaceutical production, gas sterilization is often employed. However, gas sterilization (e.g., using ethylene oxide) can be time-consuming, requiring prehumidification, heating, and evacuation of a sample chamber, followed by treatment with high concentrations of the gas for up to 20 hours at a time. When properly used, traditional disinfectants can inactivate vegetative bacteria, certain fungi, and lipophilic or medium-sized viruses. However, these disinfectants often do not arrest tubercle bacillus, spore-forming bacteria, or non-lipophilic or small-sized viruses.
Another method for lysing cells, and thereby sterilizing a sample is described in
Microbiology
(Davis et al., Harper & Row, Hagerstown, Md., 1980). This procedure of freezing and thawing the sample is believed to exert its effect through formation of tiny pockets of ice within the cells when a suspension of bacteria is frozen. The ice crystals and the high localized concentrations of salts both cause damage to the bacteria. A single freezing event is generally sufficient to kill only some of the bacteria, but repeated freeze-thaw cycles result in a progressive decrease in viability. Lethality is correlated with slow freezing and rapid thawing.
Traditional freeze-thaw methods are limited in the speed of the freeze-thaw cycle by the time needed to transfer heat to and from the center of the sample to effect phase changes. The equilibrium rate is particularly slow in the case of large volume samples (e.g., about 100 ml or larger). Sterilization efficiency of the traditional methods is limited by the impracticality of performing a large number of freeze-thaw cycles by those methods.
Traditional methods of food preservation include pasteurization, in which a food is held at an elevated temperature for a period of time.
There is presently a need to develop methods for inactivating microbes and viruses from protein preparations while maintaining the integrity and therapeutic value of the proteins. The development of methods for inactivation of non-encapsulated viruses is especially challenging, since the outer coats of such viruses generally include proteins similar to the proteins one wishes to retain.
SUMMARY OF THE INVENTION
The invention is based on the discovery that biological and non-biological materials can be sterilized, decontaminated, or disinfected by repeatedly cycling between relatively high and low pressures. Pressure cycling can be carried out at low, ambient, or elevated temperatures (e.g., from about −40° C. to about 95° C., e.g., −40° C., −35° C., −30° C., −25° C., −20° C., −15° C., −10°C., −5° C., 0° C., 4° C., 5° C., 10° C., 15° C., 20° C., 25° C., 30° C., 35° C., 37° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., 95° C., or intermediate ranges). New methods based on this discovery can have applications in, for example, the preparation of vaccines, the sterilization of blood plasma or serum, plant, animal, and human tissue, sputum, urine, feces, water, and ascites, the decontamination of military devices, food and beverage production, and the disinfection of medical equipment. The new methods can also be incorporated into production processes or research procedures.
In general, in one embodiment, the invention features a method for sterilizing a material that includes at least one desired macromolecule (e.g., a nucleic acid, a protein, a lipid, a carbohydrate, a drug, a steroid, or a nutrient). The method includes the steps of providing the material at an initial pressure; and increasing the pressure to an elevated pressure sufficient to sterilize the material but insufficient to irreversibly inactivate the biological activity of the desired macromolecule.
The invention also features a method for sterilizing a material initially contaminated with at least one infectious agent selected from the following: a bacterium, a prion, a virus, an infectious nucleic acid, or an infectious protein. The method includes the steps of providing the material at an initial temperature and pressure; and increasing the pressure to an elevated pressure sufficient to sterilize the material. The initial temperature is generally lower than 60° C.
Examples of contaminants that can be destroyed or inactivated by these new methods include, but are not limited to, bacteria, prions, viruses, fungi, protists, nucleic acids, and proteins.
In some cases, the method can also include decreasing the pressure to a decreased pressure, and cycling the pressure between the decreased pressure and the elevated pressure at least two times (e.g., 2, 3, 4, 5, 6, 8, 10, 20, 25, 50, 100, 250, 500, 1000 times or more). The decreased pressure can be the same as or different from the initial pressure, and is typically (although not necessarily) about half of the elevated pressure or less. Thus, if the elevated pressure is 40,000 psi, the decreased pressure will generally be 20,000 psi, 10,000 psi, 5,000 psi, 1,000 psi, 500 psi, 250 psi, 100 psi, 50 psi, 20 psi, 1 atm or less, or any intermediate value.
The invention also features a method for sterilizing a material. The method includes the steps of providing the material at an initial temperature and pressure; increasing the pressure to an elevated pressure sufficient to sterilize the material; decreasing the pressure to a decreased pressure; and repeating the increasing and decreasing steps at least once. In this method, the initial temperature can be, for example, about 40° C. or lower.
The material sterilized by the above methods can be, for example, a biological sample; blood plasma, serum, or other plant, animal (including insects, mammals, reptile, etc.), or human tissue; feces; urine; sputum; medical or military equipment; a foodstuff; a pharmaceutical preparation; ascites; a vaccine; or any other material to be sterilized.
The initial pressure can be, for example, atmospheric pressure (i.e., about 1 atm, or about 14.7 psi), or a lower pressure (less than 1 atm, e.g., 0.01 psi, 0.1 psi, 1 psi, 10 psi, or intermediate pressures) or a higher pressure (greater than 1 atm, e.g., 20 psi, 50 psi, 100 psi, 200 psi, 500 psi, 1000 psi, 2000 psi, 5000, 10000 psi, 20,000 psi, or higher). The material can be provided at an initial temperature in the range of from about −40° C. to about 95° C. (e.g., −40° C., 35° C., −30° C., −25° C., −20° C., −15° C., −10° C., −5° C., 0° C., 4° C., 5° C., 10° C., 15° C., 20° C., 25° C., 30° C., 35° C., 37° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C
Bradley David W.
Hess Robert A.
Laugharn, Jr. James A.
BBI BioSeq, Inc.
Fish & Richardson P.C.
McKane Elizabeth
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