Luminescent labels generate light through biological or chemical reactions rather than requiring excitation light, as is the case for fluorescent labels. This provides extremely low background and high sensitivity for immunoassays, clinical diagnostics, and molecular detection. Acridinium esters are the most widely used direct chemiluminescent labels, producing flash luminescence when triggered by alkaline hydrogen peroxide.

AAT Bioquest offers a variety of luminescent labels, summarized in the table below.

Acridinium can be used as a direct chemiluminescent label that emit light when triggered by alkaline hydrogen peroxide. It is the gold standard for high-sensitivity immunoassays and is used in major clinical diagnostic platforms. For improved sensitivity and stronger luminescence signals, Lumiwox™ acridinium NHS ester is recommended. This compound remains attached to the labeled biomolecule (e.g., protein) after activation, unlike standard acridinium labels, which are lost upon hydrogen peroxide-induced chemiluminescence reactions.

How it works: The acridinium ester reacts with hydrogen peroxide under alkaline conditions, producing N-methylacridone in an excited state that emits light at ~430 nm as it returns to ground state.

RuFluor™ generates luminescence through electrochemical excitation and is useful for ECL-based platforms.

In addition to reactive luminescent tags, AAT Bioquest also offers substrates for enzyme-based chemiluminescent detection that generate light when processed by an appropriate enzyme, such as HRP or ALP.

Luminol is oxidized by HRP in the presence of hydrogen peroxide to produce blue light (~425 nm). These signals can be enhanced with p-coumaric acid or other enhancers.

ReadiUse™ APS-5 is an acridan-based substrate for alkaline phosphatase that provides rapid signal development and detection limits below 10⁻¹⁹ moles of ALP.