What is the Difference Between Dot Blot and Slot Blot

The main difference between dot blot and slot blot is that a dot blot uses a dilation series of a sample for testing, whereas a slot blot uses a group of random samples.

Dot blot and slot blot are two techniques that do not use gel electrophoresis to separate proteins or nucleic acids. Only the intensity of the signal depends on the concentration of the analyte in the sample.

Key Areas Covered

1. What is Dot Blot
– Definition, Facts, Importance
2. What is Slot Blot
– Definition, Facts, Importance
3. Similarities Between Dot Blot and Slot Blot
– Outline of Common Features
4. Difference Between Dot Blot and Slot Blot
– Comparison of Key Differences

Key Terms

Dot Blot, Slot Blot

What is Dot Blot

Dot blot is a simplification method of the western blot method that detects proteins. Importantly, it does not separate the sample by gel electrophoresis in the beginning. Instead, the sample is directly applied as a single dot on the membrane. Although it is a simple method, it saves time in contrast to gel electrophoresis and chromatography. However, it does not reveal the size of the protein. Importantly, the intensity of the dot is proportional to the concentration of the protein present in the sample. The general protocol of dot blot involves the spotting of 1-2 microliters of the sample onto a PVDF or nitrocellulose membrane. After drying, a blocking buffer is added to prevent the non-specific binding of antibodies onto the membrane. Then, the incubation of the membrane with the primary antibody allows the colorimetric identification of the protein as the primary antibody is bound to the conjugate molecule.

Figure 1: Dot Blot

Furthermore, the conjugated molecules used in dot blot include HRP or alkaline phosphatase. The addition of the substrate allows the color to appear.

What is Slot Blot

Slot blot is another technique of molecular biology used to analyze a large number of samples in a single experiment. Therefore, the geometry of the blot is a key difference between dot blot and slot blot. Also, both techniques are important alterations of the western blot. Since they do not use gel electrophoresis, the sample is not separated according to size. Similar to dot blot, the sample that contains the target protein is added directly onto the nitrocellulose or PVDF membrane. Blocking, antibody incubation, and the detection of the target protein are also similar to the dot blot. Importantly, the samples that contain the target protein produce gray color bands on the membrane.

Figure 2: Slot Blot

Moreover, slot blot does not use a dilution series of the sample. It uses random samples in the assay. Therefore, it allows us to determine the presence or absence of the target protein in the sample. Importantly, the intensity of the band depends on the concentration of the target protein.

Similarities Between Dot Blot and Slot Blot

• Dot blot and slot blot are two techniques that determine the presence of a protein and nucleic acid in the sample.
• They do not use gel electrophoresis to separate samples according to size.
• The intensity of the sample gives the concentration of the analyte.

Difference Between Dot Blot and Slot Blot

Definition

Dot blot refers to a method of identifying DNA, RNA, and Protein in the sample. In contrast, slot blot refers to an approach to analyzing a large number of samples in a single experiment.

Sample Size

A dot blot uses a small number of samples, while a slot blot uses a large number of samples.

Characteristics

Dot blot uses a dilation series of a sample for testing, while slot blot uses a group of random samples.

Target Detection

Dot blot produces spots in the presence of the target protein, while slot blot produces bands.

Conclusion

In brief, dot blot and slot blot are two techniques in molecular biology that do not use gel electrophoresis for the separation of the sample by size. Also, both techniques are important for the analysis of nucleic acids and proteins. Dot blot analyzes a small number of samples. Also, it analyses a dilution series of the sample. It produces spots in the presence of the target protein. In comparison, slot blot analyzes a large number of samples. However, it does not use a dilution series of the sample. It produces bands in the presence of the target protein. Therefore, the main difference between dot blot and slot blot is their characteristics.

References:

1. Bio-Rad. (n.d.). Test blots, slot blots & dot blots – immunodetection: Bio-rad. Bio. 

Image Courtesy:

1. “Dot blot de ADN” By UPODMG 1213 lmorgue – Own work (CC-BY SA 3.0) via Commons Wikimedia
2. “Slot Blot Technique with Chicken Genomic DNA (2005)” By Spring Images – Own Work (CC-BY 2.5) via Commons Wikimedia