No, micro centrifuge tubes do not always need to be sterile. The necessity for sterility depends on the specific application you're using them for. Here's a breakdown to help you decide:

When Sterile Tubes Are Necessary

• Working with sterile samples: If your experiment involves starting with sterile materials or needs to maintain sterility throughout the process (e.g., cell culture experiments), you should definitely use sterile micro centrifuge tubes. These tubes typically undergo gamma irradiation to eliminate any microorganisms on their surface.
• Minimizing contamination risks:Even if your starting materials aren't sterile, using sterile tubes can significantly reduce the risk of contamination during sample handling and manipulation. This is especially important for experiments where even minor contamination can affect your results.

When Non-Sterile Tubes May Suffice

• Non-critical applications: For some less sensitive applications where maintaining sterility isn't crucial, non-sterile tubes may be perfectly acceptable. For example, if you're simply storing non-critical samples or using them for temporary sample holding during centrifugation, non-sterile tubes can be a cost-effective option.
• Aseptic Techniques Mitigate Risk: Even with non-sterile tubes, following proper aseptic techniques during sample handling is essential. This involves practices like using sterile pipettes, working in a clean environment, and minimizing contact with the inside of the tube to reduce the risk of introducing contamination.

Here are some additional factors to consider

• Cost: Sterile tubes are typically more expensive than non-sterile ones. If sterility isn't a critical requirement for your experiment, using non-sterile tubes can help save costs.
• Availability: Sterile tubes might not always be readily available in all labs or stores. Non-sterile options are generally more widely available.

Ultimately, the decision of whether to use sterile or non-sterile micro centrifuge tubes depends on the specific needs of your experiment and the level of contamination risk you're willing to tolerate. If you're unsure, consulting your lab protocols or a supervisor familiar with your application can help you make the best choice. And then you might want to figure out what are some common mistakes people make when using microcentrifuge tubes, and how can they be avoided.