beadtests

Beadtests are bead-based analytical assays that use microscopic or macroscopic beads as a substrate or carrier to capture and report on target molecules. They are used in chemistry, biology, and medicine to detect proteins, nucleic acids, pathogens, or small molecules.

Principle: beads are functionalized with capture molecules such as antibodies, oligonucleotides, or aptamers to create a capture surface. In a typical workflow, samples are incubated with beads, targets bind, beads are separated (for example, magnetic beads) and signals are read by fluorescence, luminescence, or colorimetric methods. Multiplexing is achieved by using beads that carry distinct identification signatures (color codes or barcodes) allowing simultaneous assays in a single sample.

Types and readouts: Magnetic beads are commonly used for separation; polymer or silica beads provide different surface chemistries. Color-coded bead sets enable multiplex platforms, such as those used in bead-based immunoassays. Bead-based approaches include immunoassays and nucleic acid assays. Readouts typically involve flow cytometry, plate readers, or optical or electrochemical detectors.

Applications: Beadtests are employed in clinical diagnostics (for example, cytokine panels and infectious disease testing), basic and translational research (protein interactions, gene expression profiling), environmental and food safety testing, and drug discovery and pharmacodynamics assessments.

Advantages and limitations: Beadtests offer high sensitivity and specificity, low sample volumes, and multiplexing capabilities, with scalability to high-throughput workflows. Limitations include higher cost, need for specialized equipment and reagents, potential cross-reactivity, batch-to-batch variability, and more complex data analysis.