Sterilisation is essential in laboratories to ensure that equipment and materials are free from microorganisms. This key process aims to solve two main problems, eliminate factors that can affect the accuracy of results, and avoid or kill harmful microorganisms. Sterilisation eliminates all forms of life, including bacteria, viruses, fungi, and spores. In this blog post, we will discuss the best methods of sterilisation for commonly used lab equipment.
1. Autoclaving
Autoclaving is the most commonly used method of sterilisation in laboratories. It involves the use of high pressure and temperature to kill microorganisms. Lab technicians place equipment in a sealed chamber that uses steam at a high temperature. And, this is usually done between 15 pounds of pressure per square inch (psi) for 15 to 30 minutes. Therefore, autoclaving is suitable for applications such as:
- Media Preparation: Researchers autoclave nutrient media and buffers to sterilise them, ensuring their purity for microbial culture and biological experiments.
- Surgical Instruments: Autoclaves sterilise surgical tools and equipment in facilities conducting animal studies, ensuring procedures remain infection-free.
- Glassware Sanitisation: Autoclaving glassware such as flasks, bottles, and test tubes eliminates all microbial life, preserving the integrity of experiments.
- Waste Management: Labs autoclave biohazardous waste before disposal to neutralise infectious agents, safeguarding public health and the environment.
- Culture Vessels: Researchers use autoclaves to sterilise culture vessels like petri dishes and bioreactors, preparing them for safe cell and microorganism growth.
- Pipette Tips and Tubes: To avoid cross-contamination, labs autoclave both disposable and reusable pipette tips and centrifuge tubes, ensuring they're free of DNA, RNA, and enzymes between samples.
- Protective Gear: Labs autoclave reusable lab coats, goggles, and gloves to eliminate biological hazards, protecting personnel from harmful agent exposure.
2. Dry Heat Sterilisation
Dry heat sterilisation is a method of sterilisation that uses high temperatures to kill microorganisms. This method is suitable for equipment that cannot withstand moisture. Lab personnel places a piece of equipment in an oven and heated to a temperature of 160°C for two hours or 170°C for one hour. Dry heat sterilisation is ideal for applications such as:
- Metal Instruments: Tools like scalpels and forceps use dry heat to ensure they're free from microbes and safe for medical procedures.
- Glassware: Laboratories use dry heat sterilisation to prepare glass items like Petri
- Powders and Oils: To avoid moisture-related contamination, labs apply dry heat to sterilise heat-stable powders and oils. This is done to preserve their purity for research use.
- Thermally Stable Equipment: Dry heat sterilises equipment that can withstand high temperatures but might degrade with moisture, like certain plastics and silicone materials.
- Dental Tools: Dental clinics employ dry heat sterilisation for their tools, ensuring patient safety by eliminating pathogens without corroding the instruments.
- Lab Benches: Specialists use dry heat to decontaminate laboratory benches and surfaces, providing a sterile workspace that minimises the risk of sample contamination.
- Veterinary Instruments: In veterinary practices, dry heat sterilisation ensures that surgical and diagnostic tools are free of infectious agents, protecting animal health.
3. Chemical Sterilisation
In chemical sterilisation, the lab equipment is soaked in a chemical solution for a specified time to kill the microorganisms. Researchers commonly use chemicals like ethylene oxide gas and hydrogen peroxide as chemical agents for sterilisation.
So, this method is suitable for heat-sensitive equipment, but it requires proper ventilation and handling of the chemicals. We recommend using chemical sterilisation for lab equipment like:
- Endoscopes: Medical staff sterilise sensitive endoscopes with chemical solutions, ensuring they're safe for patient procedures without damaging delicate components.
- Thermolabile Instruments: Labs use chemical sterilants for instruments that cannot withstand heat, preserving their functionality while eliminating microbes.
- Plasticware: Chemical sterilisation effectively disinfects plastic lab supplies, avoiding the warping or melting that can happen with dry heat sterilisation.
- Electronic Devices: Technicians apply chemical sterilants to sterilise lab electronics, protecting intricate circuits from heat damage while ensuring cleanliness.
- Surgical Gowns: Hospitals use chemical methods to sterilise non-woven surgical gowns, maintaining their integrity and providing a sterile barrier during operations.
- Rubber Items: Chemical sterilisation preserves the elasticity of rubber lab components, ensuring they remain sterile without heat-induced hardening.
- Biological Safety Cabinets: Staff periodically treat biological safety cabinets with chemical sterilants, safeguarding against contamination without harming sensitive equipment.
4. UV-C Radiation
UV-C radiation kills microorganisms if used for a specified time. For example, laminar flow hoods and biological safety cabinets do not easily sterilise. As such, UV-C radiation is a greater sterilisation method for surfaces and equipment than other methods. Here are some examples of the use of UV-C radiation in various applications:
- Safety Cabinets: Sterilising biological safety cabinets and PCR workstations to prevent sample contamination.
- Water Purification: UV-C radiation is used in lab water purification systems to kill microorganisms, ensuring sterile water for experiments.
- Air Purification: Integrated UV-C lamps in HVAC systems or standalone air purifiers sterilise lab air, reducing airborne transmission risks.
- Glassware and Plasticware: Lab glassware and plasticware like petri dishes and pipettes.
- Small Lab Instruments: Scissors and forceps, for example, are sterilised in UV-C chambers.
- Laboratory Surfaces: UV-C disinfection robots or devices sterilise lab countertops and surfaces to reduce pathogen transmission.
- PPE Storage Cabinets: UV-C lamps inside storage cabinets ensure lab coats, gloves, and goggles are free from microbial contamination.
5. Filtration
Filtration is a method of sterilisation that uses filters to remove microorganisms from liquids or gases. A filter traps microorganisms when the equipment passes through it. Therefore, this method is best for heat-sensitive liquids and gases, such as culture media and air in cleanrooms. Other examples include:
- Air Purification: Facilities filter air through high-efficiency particulate air (HEPA) filters, removing contaminants to maintain a clean laboratory environment.
- Water Treatment: Labs use filtration systems to purify water, ensuring it's free from microorganisms and suitable for sensitive experiments.
- Sterile Solutions: Researchers filter solutions such as media or reagents to sterilise them, preventing microbial contamination in culture studies.
- Vaccine Production: Pharmaceutical companies apply filtration to remove impurities from vaccines, ensuring their safety and efficacy.
- Protective Equipment: Manufacturers incorporate filters into protective masks and hoods, providing breathable air that's free from pathogens and particulates.
- Cell Culture: Scientists use filters to sterilise cell culture media, safeguarding the growth of cells from unwanted microbial interference.
- Ventilation Systems: Hospitals and labs install filters in ventilation systems, preventing the spread of airborne diseases and maintaining sterile conditions.
6. Irradiation
This method of sterilisation uses ionising radiation to kill microorganisms. Irradiation uses gamma rays, electron beams, or X-rays to kill the microorganisms on lab equipment. So, laboratories use irradiation for equipment that cannot be sterilised by other methods, such as:
- Culture Media Containers: Researchers sterilise containers for culture media using irradiation. This is to prevent contamination and are ready for microbial growth experiments.
- Surgical Sutures: Medical laboratories use irradiation to sterilise surgical sutures, guaranteeing sterility and safety for patient care.
- Pipettes and Tips: Irradiation sterilises pipettes and tips, allowing researchers to conduct precise measurements in sterile conditions.
- Petri Dishes: By applying irradiation, labs ensure petri dishes are sterile. It’s crucial for accurate microbial culture studies.
- Biopsy Tools: Pathology labs sterilise biopsy needles and tools with irradiation, preventing cross-contamination between samples.
- Laboratory Gloves: Irradiation sterilises gloves, providing a safe and sterile barrier for handling sensitive or hazardous materials.
- Centrifuge Tubes: Centrifuge tubes are sterilised through irradiation, making them safe for use in experiments involving DNA, RNA, or protein analysis.
So which of these methods of sterilisation is the best?
The answer depends on the lab equipment and materials you're working with. Researchers commonly use autoclaving because of its versatility and effectiveness. However, dry heat sterilization is ideal for equipment that cannot withstand moisture, while chemical sterilization is suitable for heat-sensitive equipment. Ultimately, the method you choose depends on the specific needs of your lab and the equipment you're using.
