Why is PBS Used for Washing?

PBS, or phosphate-buffered saline, is a frequently used solution in a wide range of applications that involve biological research, cell culture experiments, and general laboratory work. Its remarkable versatility stems from its ability to cleanse and maintain a neutral pH, making it an indispensable tool in various fields, including cell biology, microbiology, immunology, and biochemistry.

1. Buffering Properties:

PBS stands out due to its exceptional ability to maintain a constant pH. When acidic or alkaline substances are added to PBS, its buffering system quickly neutralizes them, preventing drastic pH changes. This stability is crucial for preserving the structural integrity and functionality of biological samples, as pH fluctuations can profoundly impact cellular processes. The pH of PBS is typically adjusted to 7.4, mirroring the physiological conditions found in the human body, enabling it to mimic the natural environment of cells and tissues.

2. Non-Toxic and Non-Reactive:

PBS is non-toxic to cells, ensuring that it can be employed without compromising the viability or function of biological samples. Its non-reactivity with biological molecules further adds to its utility. This remarkable inertness allows PBS to be used as a washing solution without interfering with cellular components or delicate experimental reagents.

3. Versatility:

The versatility of PBS extends beyond its use as a washing solution. It serves as a diluent for various biological samples and reagents, facilitating accurate and precise measurements. Its isotonicity, closely matching the osmotic properties of cells, prevents cellular damage during sample preparation and processing. Moreover, PBS is widely used in cell culture media to maintain optimal conditions for cell growth and proliferation.

4. Washing Applications:

A) Cell Washing:

PBS plays a pivotal role in cell washing procedures, where it gently removes cellular debris, culture media components, and unwanted substances while preserving cell integrity. This process is essential in cell culture techniques, experimental procedures, and flow cytometry, where pure and viable cells are paramount.

B) Sample Dilution:

PBS serves as an ideal diluent for preparing dilutions of biological samples. Its neutral pH and low ionic strength minimize sample interference, ensuring accurate and reliable results in downstream experiments. Dilutions using PBS are commonly employed in assays, enzyme reactions, and immunological techniques.

C) Reagent Preparation:

PBS is often used to dissolve and dilute reagents, creating solutions with specific concentrations and properties. Its inert nature ensures that it does not interfere with or alter the activity of the dissolved reagents, making it a suitable diluent for maintaining reagent stability and integrity.

5. Common Uses:

The versatility of PBS extends to a plethora of applications across various scientific disciplines:

  • Cell culture: Maintaining optimal conditions for cell growth and proliferation.
  • Protein purification: Removing impurities and contaminants from protein samples.
  • Immunoassays: Diluting antibodies and preparing buffers for antigen-antibody reactions.
  • Flow cytometry: Preparing cell suspensions for cell sorting and analysis.
  • Molecular biology: Diluting DNA and RNA samples for PCR and other nucleic acid-based techniques.
  • Microbiology: Washing bacterial and fungal cultures, preparing microbial suspensions, and diluting antibiotics.


PBS is an invaluable tool in the armamentarium of researchers, serving as a multi-purpose solution for washing, diluting, and maintaining the integrity of biological samples. Its remarkable versatility, non-toxicity, non-reactivity, and buffering capabilities make it a trusted and essential reagent in numerous laboratory applications. PBS continues to be an indispensable component in the pursuit of scientific knowledge and advancements.


1. In what ways is PBS superior to water for washing purposes?

PBS is far superior to water for washing as it maintains a neutral pH, mimicking physiological conditions and preventing cellular damage. Its non-toxic and non-reactive nature ensures compatibility with biological samples. Additionally, PBS prevents osmotic lysis by maintaining an appropriate osmotic pressure, which is crucial for cell viability.

2. What is the mechanism behind PBS's buffering capacity?

PBS contains a mixture of phosphate salts and sodium chloride, creating a balanced solution that resists pH changes. This buffering system neutralizes both acidic and alkaline substances, maintaining a stable pH within a narrow range.

3. Are there any specific precautions to consider when using PBS?

While PBS is generally safe and non-toxic, specific precautions should be taken to ensure its proper use. For cell culture applications, sterile PBS must be employed to prevent contamination. Additionally, PBS should be stored at 2-8°C to maintain its stability and integrity.

4. What are the advantages of using PBS in cell culture?

PBS plays a crucial role in cell culture by providing an optimal environment for cell growth and proliferation. Its isotonic nature prevents osmotic stress, while its buffer system maintains a stable pH. PBS also aids in nutrient delivery and metabolic waste removal, promoting healthy cell growth.

5. What are some alternative solutions that can be used instead of PBS?

In some instances, alternatives to PBS may be considered based on specific experimental requirements. These alternatives include Hanks' Balanced Salt Solution (HBSS), Dulbecco's Phosphate-Buffered Saline (DPBS), Roswell Park Memorial Institute (RPMI) Medium, and Minimum Essential Medium (MEM).



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