What are the types of ELISA?
There are three types of ELISA:
As followed from the image below Direct ELISA involves only one antibody, which means it is quite useful for quantities and qualitative detection of a specific antigen in a sample. Each ELISA system has its primary antibodies which need to be labeled all the time, due to the specify of this approach. Indirect is quite similar but not as specific.
As in the picture below the sandwich ELISA is a method that uses the following procedure: antibody that is used for detection is placed and coated in a plate, next a sample is added and the target antigen binds to its specific antibody, later at the third stage from left, detection antibody is added and so it covers the antigen in the form of a “sandwich”, other antibodies are also added for further detection, and then the absorbance is measured to determine the quality and quantity of the present substance.
This type of ELISA is slightly different from other types, as the image below compares, the steps for The procedure are as follows, an incubation of the antibody and antigen is set up and carried out next this mixture is placed in a coated plate of antigen, this makes the competition of binding into the antigen and creating antigen-antibody complex hence it is named competitive ELISA, after that the substrate is added and signals are formed detecting either the presence or non-presence of the target.
It is worthwhile to mention that ELISA is a great application in forensics as it helps to identify biological prints of criminals, or anyone on the crime scene. It also can provide details on some types of deaths like poisoning for example.