Speed Staining!
With the Olympics just past, questions such as how high and how fast come to the fore. So here’s our little IHC mini Olympics.
How High… can you dilute out your primary antibody?
Primary antibodies are usually the most expensive part of an IHC stain, they determine the specificity of the test and if they are not well optimised with the staining system your staining may well fall short of the bar. Apart from temperature & incubation time, the dilution achieved is normally dependent on the detection method and also on the sensitivity of the substrate used.
How Fast
Generally the fewer steps in a method the faster it is. Although there are recommended staining methods with most kits, some can come with modifications of increased concentrations and higher incubation temperatures that allow for a faster method. Medal rankings based on standard method.
How controlled?
Sometimes a balance needs to be found between strength and precision. As with sports, you also have to deliver in the test, as well as in ‘training’.
Although more layers can increase sensitivity, each can introduce more opportunity for unwanted background and then it takes more to With each layer, any existing unwanted reactions are also amplified, and usually cost!
Detection Method Medal Table
| Event | |||
Detection Methods | Highest Primary Dilution (Sensitivity) | Fastest Method | Ease of trouble shooting / background control | Examples |
Polymer/ ABC & Tyramide | 1 | 4 | 3 | Biotinyl Tyramide [Signal Amplifier], ( tyramide) * |
Amplified Polymer | 2 | 3 | 2 | |
Polymer | 3 | 1 | 1 |
|
ABC (with Secondary) | 3 | 2** | 2 | |
Labelled Primary & HRP Streptavidin | 4 | 1 | 1 |
- Fluorescent tyramides also available here. Fluorescent mounting media recommended.
** A rapid staining method is available
Photo finish
At the end of the method finishing the sections for imaging is also important and can impact on the time taken, although there are restrictions as to appropriate mountants based on chemical compatibility which must be the primary consideration.
| Event | ||
Section Mounting | Speed to microscope post mounting | Longevity | Examples |
Permanent (Non-Aqueous) Dehydration Required | 3 | 1 |
|
Non-Aqueous Express | 1 | 2 | |
Aqueous | 1 | 3 |