How much do you know about sterilization methods?

Date:2022-05-13 0:00:00 Friday

Summary: Sterilization refers to the process used to confirm that a product is free of any form of viable microorganisms (NMPA. YY0033-2000. Good Manufacturing Practice for Sterile Medical Devices [S]). Sterilization refers to the techni......

Sterilization refers to the process used to confirm that a product is free of any form of viable microorganisms (NMPA. YY0033-2000. Good Manufacturing Practice for Sterile Medical Devices [S]). Sterilization refers to the technique of killing or removing the propagules and spores or spores of all microorganisms. At present, there are the following sterilization methods commonly used in medical and experimental research related equipment and various types of equipment and consumables.

Physical sterilization

Autoclave (moist heat sterilization)

An autoclave is a vessel similar to a pressure cooker. Place the object to be sterilized in it and seal it. It is then filled with high-temperature steam under high pressure to replace air. Moist heat kills microorganisms through irreversible coagulation and denaturation of enzymes and structural proteins. The time and temperature at which this is achieved depends on the pressure and the type of microorganism being killed. After the necessary time has elapsed, the steam is released and the sterilized object is removed. The cycle lasts 15-60 minutes.

The advantages of this sterilization method are non-toxic, environmentally friendly, easy to control and monitor the process, fast and effective sterilization, minimal impact of organic or inorganic dirt in the sterilization process, and short sterilization cycle time. The disadvantage is damage to heat-sensitive instruments, repeated sterilization exposure can damage precision surgical instruments, may cause instrument rust due to wet packing, and potential burn risk.

Chemical sterilization

A. Ethylene oxide (EO) sterilization

The basic principle of EO sterilization is that ethylene oxide induces cell death by alkylating proteins, DNA, and RNA, irreversibly preventing the metabolism and replication of normal cells. The sterilization process includes five steps: steam evacuation, gas injection, diffusion, evacuation and air flushing. After completion, ventilation operations are required to drain EO. Mechanical ventilation takes 8-12 hours at 50°C-60°C, and passive ventilation can also be used, but it takes a long time, taking about a week. After ventilation is complete, remove the sterilized object.

The sterilization method can sterilize heat- and moisture-sensitive medical equipment without harmful effects on its materials, but the method is costly, and ethylene oxide is toxic, carcinogenic and flammable, and the tank must be stored in an explosion-proof storage cabinet, which may cause potential harm to personnel around the sterilization environment, and requires long-term analysis to remove ethylene oxide gas residues.

B. Hydrogen peroxide plasma sterilization

Hydrogen peroxide sterilization is the use of hydrogen peroxide plasma with high oxidative activity to kill microorganisms by destroying cell proteins, enzymes and nucleic acids. The method is safe and environmentally friendly, no toxic substances remain, sterilization cycle 28-75 min, no need to analyze, suitable for heat and moisture sensitive sterilization, easy to operate, install and monitor, and compatible with most instruments. However, this method is not suitable for paper fibers, cotton and linen and liquids.

Radiation sterilization

A. Ionizing radiation sterilization

Taking γ radiation as an example, its sterilization principle is to use the γ rays emitted by the radioactive isotope cobalt 60 as an effective sterilization factor, and γ rays can induce cells to produce free radicals, destroy normal metabolism, and then lead to the inactivation of microorganisms. γ radiation can penetrate deep into the object, it is faster than physical and chemical methods, and it occurs at higher than room temperature and standard atmospheric pressure.

B. Electron beam sterilization

The method is to place the object to be sterilized in a conveyor device and slowly pass through the window of the electron beam generator. The speed of the delivery device is selected to ensure that the radiation dose is appropriate for continuous processing. Achieving the penetration depth required for sterilization requires energy levels in the order of 5 MeV to 10 MeV. Electron beam radiation forms free radicals that react with polymers, damaging DNA and causing cell death. The method destroys all types of pathogens, including viruses, fungi, bacteria, insects, spores, and mold.

The electron beam radiation has strong penetration, fast sterilization speed, cyclic sterilization, and safe and controllable, no radiation after shutdown. Because of its comprehensive, efficient, stable, safe and residue-free sterilization characteristics, Amngent has also chosen the electron beam sterilization method to sterilize various consumables such as centrifuge tubes, petri dishes, and cryopreservation tubes.