bioassay

BioAssay is a laboratory method that uses living systems or biological components to measure the effects of a substance. It is designed to quantify biological activity, potency, or toxicity rather than chemical concentration alone, and is widely used in drug development, diagnostics, and environmental testing.

Bioassays are typically categorized into cell-based assays and biochemical or immunoassays. Cell-based assays monitor cellular responses such as viability, proliferation, signaling pathway activation, or reporter gene expression. Biochemical assays measure an enzyme's activity or the interaction between molecules, while immunoassays detect target substances using antibody binding, often producing a measurable signal like color, fluorescence, or chemiluminescence.

Readouts may rely on optical, luminescent, colorimetric, radioactive, or electrochemical signals, and can be performed in microplate formats for high-throughput screening. Selection of an assay depends on the target, required sensitivity, specificity, throughput, and the available biological system.

Applications include evaluation of drug candidates' potency and safety, diagnostic tests and potency assays for biologics, quality control of vaccines and biologics, and environmental monitoring for pollutants that affect biological systems.

Validation and standardization are important to ensure reliability. Assays are evaluated for accuracy, precision, dynamic range, and robustness, and may be conducted under Good Laboratory Practice or regulatory guidelines when used for regulatory decisions.