A cell strainer is a common laboratory tool designed to separate cells or particles based on their size. It functions as a mechanical sieve with a mesh screen, allowing smaller components to pass through while retaining larger ones. This device plays a fundamental role in preparing biological samples for scientific experiments, ensuring sample quality before analysis. Designed for ease of use, cell strainers often fit directly onto standard laboratory tubes.
Purpose of Cell Strainers in Research
Cell strainers are widely used in biological research to prepare samples for applications like cell culture and flow cytometry. Their primary function is creating uniform single-cell suspensions from complex biological samples. This removes unwanted cell clumps, tissue fragments, or debris that could interfere with experimental accuracy.
Ensuring a consistent single-cell suspension is important for reliable experimental results. For instance, in applications like cell counting or viability assays, accurate measurements depend on individual cells rather than aggregates. Cell strainers also protect delicate downstream equipment, such as flow cytometers, from clogging by large particles or cell clumps.
Step-by-Step Cell Straining Process
Begin by preparing the sample and selecting the appropriate strainer. The sample (often a cell suspension or dissociated tissue) should be ready for filtration. Position the cell strainer securely on a collection tube, such as a 50 mL conical tube.
Gently introduce the cell suspension into the strainer by pouring or pipetting. Allow the liquid to pass through the mesh by gravity, or apply gentle pressure if the flow is slow.
Once filtered, desired cells collect in the tube below, while larger aggregates or debris remain on the strainer mesh. For maximum cell recovery, gently rinse the strainer with a small volume of appropriate buffer or medium. Maintaining an aseptic environment throughout this process is important to prevent contamination of the cell sample.
Selecting the Appropriate Cell Strainer
Selecting the correct cell strainer is important for effective sample preparation; mesh (pore) size is a primary consideration. Cell strainers are available in common pore sizes: 40 µm, 70 µm, and 100 µm. The choice depends on the cell size and experimental goal.
For example, a 40 µm strainer is often used for fine cell suspensions or to remove smaller debris while retaining single cells. A 70 µm strainer is a general-purpose size suitable for many mammalian cell types. Larger 100 µm strainers are useful for processing larger tissue fragments or removing substantial aggregates.
Beyond pore size, other factors influence selection. Most cell strainers are made of nylon or polyester mesh within a polypropylene frame and come pre-sterilized for sensitive biological applications. They fit snugly onto standard collection tubes, such as 50 mL conical tubes, ensuring compatibility with common laboratory setups.
Enhancing Straining Efficiency
Several practices optimize the cell straining process for better, more consistent results. Before adding the cell suspension, pre-wet the strainer mesh with buffer. This promotes even flow and prevents air bubbles from getting trapped.
Applying gentle pressure, either through gravity or pipetting, helps avoid damaging delicate cells. Avoiding excessive force is important, as it could compromise cell viability or push unwanted particles through the mesh. If the strainer becomes clogged with cell debris, it may be necessary to use a fresh strainer to maintain efficiency.
Ensure the sample is free of large, dense aggregates before straining. Pre-processing, such as gentle tissue disaggregation, can reduce clogging and allow smoother filtration.