Overview: Phosphate Buffered Saline (PBS)

Phosphate Buffered Saline (PBS) is a widely used isotonic buffer solution designed to maintain stable pH and osmotic balance in biological systems. It plays a critical role in workflows such as cell culture, protein purification, and immunoassays by preserving cell integrity and biomolecular structure.

PBS is valued for its simplicity, reproducibility, and compatibility across a broad range of laboratory and bioprocessing applications.

PBS is a water-based salt solution containing phosphate salts and sodium chloride that maintains physiological pH (typically 7.0–7.4) and isotonic conditions.

It is commonly used to:

• Maintain cell viability during handling
• Stabilize proteins and biomolecules
• Provide a consistent ionic environment for assays and workflows

Understanding phosphate buffered saline composition is essential for selecting the right formulation for your workflow.

Key Components

Phosphate Buffer System

• Potassium phosphate monobasic / sodium phosphate dibasic
• Maintains pH between 7.0–7.4
• At Boston BioProducts, PBS pH is typically adjusted using sodium hydroxide
• Potassium-based pH adjustment is available for potassium-sensitive workflows

Salts for Osmotic Balance

• Sodium chloride (NaCl)
• Potassium chloride (KCl)
• Maintain isotonicity and cellular stability

Specialized PBS Options

• RNase-Free PBS
  - Designed for RNA-sensitive workflows such as RNA isolation and transcriptomics
• Low Endotoxin PBS
  - Suitable for endotoxin-sensitive applications including cell therapy and immune assays
• Potassium-Free PBS
  - Used in workflows where potassium ions may interfere with biological processes

Key Features

• Non-toxic and cell-friendly for extended exposure
• Available in RNase-free and low-endotoxin formats
• Supports consistent experimental reproducibility
• Compatible with a wide range of biological workflows

Dulbecco’s PBS (DPBS) is a modified PBS formulation designed for more specialized biological applications, particularly in cell culture.

Key Characteristics:

• Higher sodium phosphate content
• Reduced potassium phosphate concentration
• Optional inclusion of:
  • Calcium (Ca²⁺)
  • Magnesium (Mg²⁺)

These additions support:

• Cell adhesion
• Cell signaling
• Enzymatic activity

Use PBS when: 

• Performing washing, dilution, or protein workflows
• Avoiding interference from divalent cations

Use DPBS when: 

• Working with live or adherent cells
• Cell signaling or enzymatic activity is required

While standard PBS provides a stable, isotonic environment, some workflows require additional functionality such as reducing non-specific binding or disrupting cell membranes. In these cases, PBS is combined with detergents to enhance performance.

PBS with detergents is commonly used in immunoassays, protein workflows, and cell lysis applications, where controlling interactions at the molecular or membrane level is critical.

Common Types of PBS with Detergents

PBST (PBS + Tween-20)
PBST contains Tween-20, a mild, non-ionic detergent that reduces non-specific interactions.

Ideal for:

• ELISA washing steps
• Western blot washing
• Immunostaining workflows

Key benefit:

• Improves signal-to-noise ratio by minimizing background binding

PBS with Triton X-100
Triton X-100 is a stronger, non-ionic detergent used for membrane disruption and protein solubilization.

Ideal for:

• Cell lysis
• Protein extraction
• Membrane permeabilization

Key benefit:

• Efficiently disrupts lipid membranes to release intracellular components

Use PBST when:

• You need to reduce non-specific binding in assays
• Working with antibodies or detection systems

Use PBS + Triton X-100 when:

• You need cell lysis or membrane permeabilization
• Extracting intracellular proteins

Key Considerations

• Detergent concentration can affect assay sensitivity and protein stability
• Overuse of strong detergents may disrupt protein structure
• Always match detergent type to your application (washing vs lysis)

• PBS: General workflows and washing
• DPBS: Cell culture and cell-based assays
• RNase-free PBS: RNA-sensitive applications
• Low endotoxin PBS: Immune or therapeutic workflows
• Potassium-free PBS: Potassium-sensitive systems
• PBST: Immunoassays (ELISA, Western blot)
• PBS + Triton X-100: Lysis and protein extraction

Tips

• Use sterile-filtered PBS for cell culture workflows
• Select Ca²⁺/Mg²⁺-free PBS when washing cells prior to dissociation
• Use PBST for immunoassays to reduce non-specific binding
• Match ionic composition to your biological system

Phosphate Buffered Saline (PBS) is a foundational buffer system used across life science workflows. By understanding its composition, variations (including DPBS and PBST), and application-specific considerations, researchers can select the optimal formulation for reproducible and high-quality results.

Boston BioProducts PBS products

• Browse our catalog of pre-formulated PBS, DPBS, and detergent-containing PBS (PBST and Triton X-100), each designed for specific research applications.
• Use our Custom Manufacturing / Reagent Builder to design a balanced salts solution tailored to your specific needs