Ways to Avoid Cell Contamination: Pipetting Tips You Need to Know
Among the many variables that are controlled in cell culture, one specific variable affects the entire experiment: contamination. One contributing factor to cellular contamination is not always on the radar, and although it can silently affect cell health and affect measurement data, it is pipetting contamination.
The choice of pipettes, pipette tips, and pipetting programs receives little attention when designing experiments. Even a blanket solution (autoclaving) to avoid pipetting contamination may not be as effective as is commonly believed.
The first rule of cell culture: avoid contamination. Why is sterile technique so important for successful cell culture?
Aseptic technique is the only way to obtain reliable and reproducible results. Pollution can affect cell growth, metabolism and health -- something that scientists are interested in studying. Contaminated cell lines do not have the desired properties, and they function differently each time, depending on the severity of the contamination. Also, if contaminants overgrow your cells of interest, you may end up studying the wrong organism.
What types of pollutants do scientists often encounter?
Common sources of contamination are bacteria, yeast and mold. In cell culture work, the most difficult to detect and eradicate is mycoplasma. Less common types of contamination include, for example, plastic leachables in laboratory consumables.
What are the common causes of cell contamination?
A common source of contamination is poor pipetting, such as the use of contaminated pipettes and non-filter tips. In addition, lack of good laboratory practices, such as inadequate decontamination of instruments such as incubators or laminar flow cabinets, is also an issue. To remove mycoplasma, filtration is required using a 0.1 µm filter instead of a 0.2 µm filter.
Three pipetting contaminations:
1. Pipette-to-sample contamination: The pipette or pipette tip contaminates the sample.
How to avoid:
Use sterile filter tips to prevent contamination of the pipette body.
Change the pipette tip after each sample.
Autoclave or sterilize pipettes regularly with ethanol. Choose an autoclave-compatible pipette.
2. Sample-to-pipette contamination: Pipetting the sample into the pipette body contaminates the pipette.
How to avoid:
Use filter tips or positive displacement tips to prevent samples from entering the pipette body.
When pipetting, keep the pipette in a vertical position. Store the pipette upright.
Tilt the bottle when pipetting.
Release the button slowly to avoid splashing the sample into the pipette. Choose a pipette equipped with a soft eject function.
3. Inter-sample contamination: Residual pipetting samples are transferred to the next sample. Usually occurs when the same tip is used multiple times.
How to avoid:
Change the pipette tip after each sample.
Use filter tips or positive displacement tips to prevent the sample from entering the pipette body and on to the next sample.
Make sure the pipette tip is sealed on the pipette to avoid sample leakage. For example, the tip of Yongyue Medical.
Are there contamination factors that scientists may not even be aware of?
The efficiency of autoclaving is often not verified, and if the autoclave is not working properly, the autoclaved pipette tips may not be sterile. Pre-sterilized filters wrapped in protective packaging are the safest option to prevent such accidents. The pre-sterilization process for high-quality pipette tips is regularly validated to ensure the efficiency of pre-sterilization.
How do pipetting and dispensing tools make it easier for scientists to handle samples in a sterile environment?
Choosing the right pipettes and pipette tips can make aseptic workflow easier. Yongyue medical pipettes are easy to clean and open without tools, speeding up daily cleaning. Since autoclaving is more effective at removing contamination than ethanol wipes, Sartorius mechanical pipettes are fully autoclavable, which means you can decontaminate your pipettes reliably. Soft tip ejection prevents the potential risk of contamination from splashing when the tip is ejected. Pre-sterilized filter tips protect your samples from cross-contamination. Yongyue medical tips are also packaged in leak-proof packaging, which means that any contamination under storage and delivery conditions will not come into contact with the tips or tip box.
How can scientists avoid pollution? What are your top tips for sterile work?
First, good laboratory practice and careful planning of work steps. Make sure to keep only what is needed for a specific workflow in the laminar flow cabinet and use one cell culture at the same time. Plus, regular testing for contaminants like mycoplasma gives you peace of mind and confidence in your results. When working under sterile conditions, the money spent on pre-sterilized filter tips and sterile reagents is worth the money.
