How to achieve mild separation of biological samples using a vertical low-speed centrifuge?

　　Vertical low-speed centrifugesare core equipment for mild separation of biological samples(such as cells,proteins,and nucleic acids),with a typical speed range of 3,000–10,000 r/min.Mild separation is realized by precisely controlling centrifugal force,optimizing operation parameters,and standardizing sample handling,which ensures the structural and functional integrity of sensitive biological components during separation.

The implementation of mild separation relies on four key technical steps:

1.Sample pretreatment and loading optimization

Biological samples need to be preprocessed to reduce mechanical damage before centrifugation. For cell suspensions,add an appropriate amount of isotonic buffer(e.g.,PBS)to maintain osmotic pressure and avoid cell rupture caused by concentration differences. For protein solutions,add protease inhibitors to prevent degradation during centrifugation. When loading samples,use centrifuge tubes with good compatibility(polypropylene or glass),and ensure the sample volume is consistent in each tube(error≤0.5 mL)to achieve weight balance. This avoids vibration and noise during centrifugation,which can damage fragile samples such as stem cells and exosomes.

2.Precise setting of centrifugal force and speed parameters

Unlike high-speed centrifugation that pursues high efficiency,mild separation prioritizes the use of gradient centrifugal force matching sample characteristics. Select the corresponding speed according to the sample type:for example,3,000–5,000 r/min for separating blood cells to avoid red blood cell rupture; 6,000–8,000 r/min for precipitating protein aggregates. Use relative centrifugal force(RCF)instead of speed for parameter setting,because RCF is related to both rotational speed and rotor radius,and can more accurately reflect the actual separation force acting on the sample,ensuring repeatability of separation results.

3.Temperature control and operation mode regulation

Most biological samples are temperature-sensitive,soVertical low-speed centrifuges equipped with refrigeration systems(temperature range:0–4℃)should be selected to inhibit enzyme activity and slow down sample degradation. During operation,choose a gradient acceleration and deceleration mode instead of rapid start-stop:set the acceleration time to 1–3 minutes to avoid sample stratification disorder caused by sudden centrifugal force; set the deceleration time to 2–5 minutes to prevent the resuspension of the precipitated sample layer due to inertial impact.

4.Post-centrifugation sample handling and equipment maintenance

After centrifugation,take out the centrifuge tubes gently along the vertical direction to avoid shaking the sample precipitate. For layered samples(such as serum separation from blood),use a pipette to aspirate the target layer slowly along the tube wall. After the operation,clean the rotor and centrifuge chamber with 75%ethanol to avoid cross-contamination,and check the rotor for cracks regularly to ensure stable operation of subsequent centrifugation.

By following the above steps,Vertical low-speed centrifugescan achieve mild and efficient separation of biological samples,maximizing the retention of sample activity and structural integrity,which is suitable for scientific research and clinical detection scenarios such as cell culture and protein purification.