What is the Origin of Biological Assay?

The term "assay" is derived from the Old French assai, meaning "trial" or "test," originally referring to the testing of metals. The concept evolved into "biological assay" as scientists began to use living systems to quantify the effects of drugs and biological substances in the early 20th century. This clinical practice arose from the need to standardize therapeutic agents like insulin and pituitary extracts based on their actual effect on an organism.

What is the Mechanism of Biological Assay?

The mechanism involves exposing a responsive biological system—such as a receptor-expressing cell culture—to the substance of interest and then quantifying the resulting physiological response. For instance, a hormone bioassay might measure the degree of receptor activation or the downstream production of a secondary messenger molecule. By comparing the response to a known standard, researchers can calculate the compound's potency, providing a measure of efficacy that is directly relevant to human physiology and therapeutic dosing.

Biological Assay ∞ Area

Biological Assay

Meaning

A Biological Assay, or bioassay, is an analytical procedure used to determine the potency, concentration, or biological activity of a substance, such as a hormone or peptide, by measuring its effect on a living system. This system could involve whole organisms, isolated tissues, or specific cell lines. Unlike purely chemical assays, bioassays provide a functional measurement, reflecting how a compound interacts with its biological target. In hormonal health, these assays are essential for validating the true physiological impact of a compound, moving beyond simple quantitative concentration measurements.