Bioassays can be broadly classified based on the nature of the biological system used and the type of response measured.
Types of Bioassays
Graded Response Bioassay:
Measures the intensity of a response (e.g., smooth muscle contraction, blood pressure change) with increasing doses.
A classic example is the analytical method on isolated organ bath (e.g., guinea pig ileum for histamine).
Quantal (All-or-None) Response Bioassay:
A yes-or-no response (e.g., lethal or non-lethal in animal studies).
Typically used in toxicity studies (LD50).
Matching Method or Direct Bioassay:
Compare the response produced by a single known dose of standard with that of the test sample until you find a dose of the test that matches the standard’s response.
Interpolation Method:
Construct a dose-response curve for the standard and read off the test sample’s potency from the same curve.