Fluorescence recovery after photobleaching (FRAP) enables characterization of quantitative dynamic properties such as diffusion coefficients of fluorescent molecules in living cells by analyzing the recovery of fluorescence intensity after photobleaching in a specific cellular compartment or area. To quantitatively determine high intracellular diffusion coefficients, a suitable optical system a...

The autofluorescence of the retina that originates primarily from lipofuscin fluorophores in retinal pigment epithelial cells, is observed to undergo photobleaching during the acquisition of fundus autofluorescence images. Bisretinoid fluorophores isolated from retinal pigment epithelial cells have the spectral characteristics consistent with their being the source of fundus autofluorescence. C...

We present a theoretical technique for quantifying the cellular copy-number of fluorophores that relies on the random nature of the photobleaching process. Our approach does not require single-molecule sensitivity, and therefore can be used with commonly used epifluorescence microscopes. Fluctuations arising from photobleaching can be used to estimate the proportionality between fluorescence in...

Confocal and two-photon fluorescence microscopy techniques using genetically encoded fluorescent probes are widely used in cell biology. Beyond the common problems of photobleaching and phototoxicity, we present evidence that photounbinding also has the potential to compromise such methods, especially in quantitative studies. We show that laser intensities within excitation regimes typical for ...

Dynamics of dissolved organic carbon concentration (DOC) and capacity to absorb light (color) are determined by in-lake and external properties and processes. In this study, the influence of external factors such as rainfall and solar radiation on DOC and color dynamics was assessed for a small forested lake. DOC and absorption coefficients at 440 nm (a440) ranged 4-fold from 0.46 to 1.62 mM an...

Abstract Europa’s leading-hemisphere chaos regions have a spectral feature at 450 nm that has been attributed to absorption by crystal defects in irradiated sodium chloride, known as F-centers. Some discrepancies exist between the laboratory data of chloride and observations, including ?10 shift central wavelength F-center band lack prominent 720 on Europa from M-centers, which result coalescen...

The investigation in this report aimed at providing photophysical evidence that the long-lived triplet excited state plays an important role in the non-single-exponential photobleaching kinetics of fluorescein in microscopy. Experiments demonstrated that a thiol-containing reducing agent, mercaptoethylamine (MEA or cysteamine), was the most effective, among other commonly known radical quencher...