Boster Bio Life Science Blog

Proper fixation workflows support reliable antibody performance when experiments depend on monoclonal antibodies or Polyclonal antibodies.

Importance of Fixation in IHC/ICC

Why Proper Fixation is Essential

Sample fixation is a required and crucial step for every successful IHC/ICC experiment. Appropriate fixation of samples provides the following benefits during the tissue preparation process. Without proper fixation, cellular structures can collapse, antigens may degrade, and staining results become unreliable. Reliable fixation helps achieve specific staining while minimizing background staining that can interfere with interpretation. Within standardized immunohistochemistry services, fixation parameters are carefully controlled to support consistent staining performance across diverse sample types. Controlled protocols also help preserve protein-protein interaction, enabling more accurate biological analysis.

How Fixatives Preserve Morphology and Antigenicity

Fixatives work by stabilizing proteins and other cellular components, either by creating cross-links or by precipitating molecules to maintain structural integrity. This chemical stabilization preserves the spatial arrangement of cells and tissues, allowing accurate localization of antigens and reliable analysis.

Maintaining structural integrity is especially important for studies evaluating protein-protein interaction within complex tissue environments.

Choosing which fixing solution to use depends on your sample type and antigen. Since there is no standard fixing solution for all samples, we recommend testing to determine which specific type of solution will be most appropriate and effective for antigen immobilization in your sample. Optimization often includes adjusting Incubation time to balance antigen preservation with antibody accessibility. This step is particularly important when preparing slides for a multiplex IHC service, where inconsistent fixation can compromise the detection of multiple targets within the same section. Improper fixation may increase background staining and reduce specific staining clarity. For samples undergoing diagnostic evaluation or complex biomarker analysis, an expert Pathology Review Service ensures tissue quality and fixation adequacy before interpretation, improving experimental accuracy. Expert review can help confirm compatibility with monoclonal antibodies and Polyclonal antibodies.

As an example, compare the morphologies demonstrated below using different fixatives, both photographed at the same magnification.

Differences in morphology often reflect variations in incubation time and fixation chemistry.

On the left: A paraffin section of the small intestine mucosa that has been fixed in neutral buffered formalin, a cross-linking fixative. Nuclear and cytoplasmic preservation is satisfactory but some cellular shrinkage is present.

Cross-linking fixatives typically support strong specific staining with reduced background staining when protocols are optimized.

On the right: A paraffin section of the small intestine mucosa that has been fixed in 95% ethanol, a denaturing fixative. While nuclear preservation is fair, there is substantial shrinkage of cytoplasmic and extracellular elements.

Denaturing fixatives may alter protein-protein interaction if fixation conditions are not carefully controlled.

Several fixing solutions are available for use and should be chosen based on the sample type or antigen studied in the experiment. Below are the 3 different categories of fixatives:

Selection should consider antibody type, Incubation time, and the need to limit background staining.

Aldehyde Fixatives

How Aldehyde Fixatives Work

Aldehyde fixatives are di-functional cross-linking agents, which are widely used due to their strong penetrability, low contractibility, and low background. They help keep the cross-linking between tissues and maintain the antigen.

These properties make aldehydes compatible with both monoclonal antibodies and Polyclonal antibodies.

Common Examples of Aldehyde Fixatives

• Formaldehyde
• Formalin (Neutral Buffered Formalin)
• Paraformaldehyde
• Glutaraldehyde
• Bouin’s Solution
• Zamboni’s Solution

Proper Incubation time with aldehyde fixatives is necessary to prevent excessive background staining.

Formaldehyde vs. Formalin vs. Paraformaldehyde

Formaldehyde and formalin are often referred to interchangeably. They are similar, but their chemical compositions are in fact different. Formalin (aka NBF) is a saturated water solution consisting of 37 to 40% (w/v) formaldehyde, which is diluted with a phosphate buffer to...