blottest

Blottest refers to a class of diagnostic assays that use blotting techniques to detect specific biomolecules on a membrane. The term is not standardized and is used in some discussions to refer to blot-based tests in molecular biology and clinical diagnostics. The concept builds on established blotting methods such as Southern blot (DNA), Northern blot (RNA), and Western blot (proteins), as well as dot blot and slot blot formats. In a typical blottest assay, a sample is applied to a membrane where target molecules are immobilized by binding, non-specific sites are blocked, and a labeled probe—an antibody for proteins or a nucleic acid probe for DNA/RNA—interacts with the target. Detection is achieved through chemiluminescence, fluorescence, or colorimetric signals.

Applications include detection of pathogens, verification of antibody responses, measurement of specific proteins or nucleic acids, and qualitative or semi-quantitative assessments in research and clinical labs. Blot-based tests can be simpler and cheaper than full molecular assays but generally offer lower sensitivity and dynamic range, and results can be semi-quantitative rather than absolute.

Limitations include the need for known target sequences or antibodies, potential cross-reactivity, and longer processing times for multiple samples. Modern multiplex or amplification-based methods have largely supplanted some blot-based tests in routine diagnostics, but blots remain valuable for confirmation and historical comparators.

See also: blotting, Southern blot, Northern blot, Western blot, dot blot, slot blot, ELISA.