ABSTRACT
This chapter presents a set of steady-state experiments in which the fluorescence intensity of a fluorophore increases/decreases as a result of interactions with other molecules. Practical applications are the most important drivers for fluorescence technology development. Many applications of fluorescence are based on fluorescence signal change resulting from fluorophores interacting with the surrounding environment. The chapter also presents experimental examples where the observed fluorescence intensity changes due to “trivial” effects like reabsorption of emitted light or absorption of excitation light. The apparent decrease in fluorescence due to the absorption of emitted light by absorbing background or attenuation of excitation by highly absorbing/scattering background are undesirable perturbations. Many practical biomedical applications are measurements of biological specimens that are optically dense, such as blood or tissue presenting very high absorption and scattering. Working with such samples leads to many perturbations of the fluorescence signal.
