Autofluoreszenzbildgebung

Autofluorescence is the natural emission of light by biological structures after they absorb light, without the use of external fluorescent labels. The phenomenon arises from endogenous fluorophores such as NADH, FAD, collagen, elastin, lipofuscin, porphyrins, and melanin. These molecules absorb light in the ultraviolet to visible range and re-emit at longer wavelengths, with emission colors and intensities that depend on tissue composition and excitation wavelength.

Autofluorescence is widely used as an imaging contrast in medicine. In ophthalmology, fundus autofluorescence uses blue light to excite lipofuscin in the retinal pigment epithelium, providing information about retinal health and degenerative diseases. In pathology and basic science, autofluorescence can reveal structural features of tissue and metabolic states, but strong endogenous signals can also complicate fluorescence labeling by creating background. Autofluorescence is also studied in dentistry and dermatology for lesion detection.

To distinguish endogenous signals from externally administered fluorophores or to enhance specificity, researchers employ approaches such as spectral imaging and unmixing, fluorescence lifetime imaging (FLIM), and selective excitation in the near-infrared. Reducing illumination intensity and exposure time also helps minimize photobleaching and phototoxicity. Limitations include variability among tissues, overlap of emission spectra, and a lack of universal standards for quantification. Ongoing work seeks to improve reliability, standardization, and integration with complementary imaging methods.