autofluorescensbildning

Autofluorescence is the spontaneous emission of light by endogenous fluorophores in biological tissue after excitation by light, without the need for external fluorescent labels. It arises from naturally occurring molecules that absorb light and re-emit photons at longer wavelengths. The emitted signal provides spectral and sometimes temporal information about tissue composition and metabolism.

Common endogenous fluorophores include NADH and NADPH, flavin adenine dinucleotide (FAD), lipofuscin, collagen, elastin, porphyrins, and heme-containing compounds. The spectral properties depend on the specific fluorophore. For example, NADH and NADPH typically emit blue to green light when excited near 340–360 nm; FAD emits green to yellow light with excitation around 450 nm; lipofuscin has a broad emission peak around 600–650 nm; porphyrins tend to emit in the red region when excited near 400 nm. Collagen and elastin contribute to blue-green autofluorescence in skin, connective tissue, and other areas.

Applications of autofluorescence include noninvasive imaging and diagnostic procedures across medicine and plant sciences. In ophthalmology, fundus autofluorescence helps assess retinal health. In endoscopy and intraoperative settings, autofluorescence can aid tissue-margin assessment and guidance. Autofluorescence is also used in cancer research to differentiate normal from neoplastic tissue based on metabolic and structural differences, as well as in dentistry to detect caries and demineralized lesions. In plants, autofluorescence tracks chlorophyll and phenolic compounds.

Advantages of autofluorescence include being label-free and enabling real-time information. Limitations include tissue- and condition-dependent background signals, spectral overlap between fluorophores, and potential photodamage with certain excitation wavelengths. Techniques such as spectral imaging, unmixing, and fluorescence lifetime imaging improve signal separation and interpretation.