Is the chemiluminescence of acridinium esters the same as that of fluorescence immunity?

Acridine ester chemiluminescence reagent is a commonly used detection reagent in the field of in vitro diagnostics. Its chemiluminescence is not like the substrate of HRP or ALP and can directly chemiluminescence. So what is the difference between the chemiluminescence of acridinium ester and the fluorescence in fluorescence immunity? What's the difference?

Chemiluminescence is a molecular luminescence phenomenon in which the product returns from the excited state to the ground state when a substance produces a chemical reaction. In fact, there are three types of molecular luminescence: chemiluminescence, fluorescence, and phosphorescence. Their luminescence principles are different:

Chemiluminescence in nature

1. Principles of Chemiluminescence

For example, the chemical reaction between acridine ester and hydrogen peroxide produces another acridinium ester derivative. The energy released by the reaction is absorbed by the molecules of this product and transitions to an excited state, and the excited molecule returns to the ground state. Light radiation is generated during the process. The product here is a luminous body, and the luminescent product directly participates in the reaction during this process, so it is called direct chemiluminescence. Luminol's luminescence principle is similar, but requires HRP or POD catalysis, so it is called enzymatic chemiluminescence.

2. The principle of fluorescence

When light irradiates certain atoms, the energy of the light makes some electrons around the nucleus transition from the original orbit to a higher energy orbit, that is, transition from the ground state to the first excited singlet state or the second excited singlet state. The first excited singlet state or the second excited singlet state is unstable, so it will return to the ground state. When the electron returns from the first excited singlet state to the ground state, energy will be released in the form of light, so fluorescence is generated.

3. The principle of phosphorescence

When a certain room temperature substance is irradiated with incident light of a certain wavelength (usually ultraviolet or X-ray), it absorbs the light energy and enters an excited state (usually with a spin multiplicity different from the ground state), and then slowly de-excites and emits a ratio. Outgoing light with a long wavelength of incident light.

Seeing this, many people may still not be able to distinguish, but it doesn't matter. For example, the luminescence of fireflies belongs to bioluminescence or chemiluminescence, phosphorous fire or "ghost fire" is also chemiluminescence, and fluorescent sticks are also chemiluminescence; ultraviolet rays illuminate RMB anti-counterfeiting signs to emit fluorescence; luminous pens and luminous watches belong to phosphorescence. In daily life, people usually call all kinds of faint light fluorescence in a broad sense.

In the field of analysis and detection, chemiluminescence immunoassay and fluorescence immunoassay are two different detection methods, which need to be distinguished. Luminol and acridine esters of Desheng belong to chemiluminescence reagents, and the reagents for fluorescence immunity are reagents of different systems.