Whole-object fluorescence lifetime setup for efficient non-imaging quantitative intracellular fluorophore measurements.

In the present study we introduce a Whole-Object Fluorescence Life Time (wo-FLT) measurement approach for ease and a relatively inexpensive method of tracing alterations in intracellular fluorophore distribution and in the physical-chemical features of the microenvironments hosting the fluorophore. Two common fluorophores, Rhodamine 123 and Acridine Orange, were used to stain U937 cells which were incubated, with and without either Carbonyl cyanide 3-chlorphenylhydrazon or the apoptosis inducer H(2)O(2). The wo-FLT, which is a non-imaging quantitative measurement, was able to detect several fluorescence decay components and corresponding weights in a single cell resolution.

The individual-cell-based cryo-chip for the cryopreservation, manipulation and observation of spatially identifiable cells. II: functional activity of cryopreserved cells.

Background: The cryopreservation and thawing processes are known to induce many deleterious effects in cells and might be detrimental to several cell types. There is an inherent variability in cellular responses among cell types and within individual cells of a given population with regard to their ability to endure the freezing and thawing process. The aim of this study was to evaluate the fate of cryopreserved cells within an optical cryo apparatus, the individual-cell-based cryo-chip (i3C), by monitoring several basic cellular functional activities at the resolution of individual cells.

The individual-cell-based cryo-chip for the cryopreservation, manipulation and observation of spatially identifiable cells. I: methodology.

Background: Cryopreservation is the only widely applicable method of storing vital cells for nearly unlimited periods of time. Successful cryopreservation is essential for reproductive medicine, stem cell research, cord blood storage and related biomedical areas. The methods currently used to retrieve a specific cell or a group of individual cells with specific biological properties after cryopreservation are quite complicated and inefficient.

Polymer live-cell array for real-time kinetic imaging of immune cells.

Direct quantitative experimental investigations of the function of lymphocytes and other immune cells are challenging due to the cell mobility and the complexity of intercellular communications. In order to facilitate such investigations, an in vitro system is required that is noninvasive and provides kinetic data on cellular responses to challenges such as drug treatments. The present work reports the development of a disposable, inexpensive polymer-made device, the Polymer Live Cell Array (PLCA), for real-time, kinetic analysis of immune cells.

Fluorescence resonance energy transfer imaging via fluorescence polarization measurement.

Fluorescence resonance energy transfer (FRET) has become a widely used spectroscopic tool for detecting molecular interactions and molecular proximity in solution, as well as in membranes. On the other hand, fluorescence polarization (FP) is a convenient measure: ratiometric and simple to execute. This work presents a novel methodology for determining energy transfer efficiency (E) via FP measurement.

Influence of fluorescence anisotropy on fluorescence intensity and lifetime measurement: theory, simulations and experiments.

The significance of fluorescence anisotropy in fluorescence intensity and lifetime measurements, and erroneous measurements and interpretations resulting from its disregard, are thoroughly discussed, formulated and quantified. In all fluorescence-related measurements--including excitation and emission spectra, relative fluorescence intensity (FI), fluorescenc life time (FLT), fluorescence resonance energy transfer (FRET), etc., with the exception of fluorescence polarization and anisotropy--it is generally true that the higher the fluorescence anisotropy, the greater the distortion of fluorescence measurements.