Electronically Preresonant Stimulated Raman Scattering Microscopy of Weakly Fluorescing Chromophores.

Stimulated Raman Scattering microscopy is an important imaging technique. Its broader application, however, is hampered by its comparatively low sensitivity. Using organic fluorophores, it has recently been demonstrated that, similar to spontaneous Raman microscopy, the sensitivity of stimulated Raman microscopy is increased by orders of magnitudes if electronic preresonances are exploited.

Influence of chain length and branching on poly(ADP-ribose)-protein interactions.

Hundreds of proteins interact with poly(ADP-ribose) (PAR) via multiple PAR interaction motifs, thereby regulating their physico-chemical properties, sub-cellular localizations, enzymatic activities, or protein stability. Here, we present a targeted approach based on fluorescence correlation spectroscopy (FCS) to characterize potential structure-specific interactions of PAR molecules of defined chain length and branching with three prime PAR-binding proteins, the tumor suppressor protein p53, histone H1, and the histone chaperone APLF. Our study reveals complex and structure-specific PAR-protein interactions.

Imaging Arm Regeneration: Label-Free Multiphoton Microscopy to Dissect the Process in .

Cephalopod mollusks are endowed with an impressive range of features that have captured the attention of scientists from different fields, the imaginations of artists, and the interests of the public. The ability to spontaneously regrow lost or damaged structures quickly and functionally is among one of the most notable peculiarities that cephalopods possess. Microscopical imaging techniques represent useful tools for investigating the regenerative processes in several species, from invertebrates to mammals.

Live Cell Imaging of Enzymatic Turnover of an Adenosine 5'-Tetraphosphate Analog.

The hydrolysis of nucleotides is of paramount importance as an energy source for cellular processes. In addition, the transfer of phosphates from nucleotides onto proteins is important as a post-translational protein modification. Monitoring the enzymatic turnover of nucleotides therefore offers great potential as a tool to follow enzymatic activity.

Double modulation SRS and SREF microscopy: signal contributions under pre-resonance conditions.

Pre-electronic resonance enhancement can increase the sensitivity of non-linear Raman microscopy to the single molecule detection limit. A major problem, however, is the generation of background signal due to unwanted linear and non-linear photophysical processes. In this work, we report the setup of a novel detection scheme for stimulated Raman scattering microspectroscopy based on the simultaneous modulation of pump and Stokes beam.

Beyond the borders--Biomedical applications of non-linear Raman microscopy.

Raman spectroscopy offers great promise for label free imaging in biomedical applications. Its use, however, is hampered by the long integration times required and the presence of autofluorescence in many samples which outshines the Raman signals. In order to overcome these limitations, a variety of different non-linear Raman imaging techniques have been developed over the last decade.

Water-soluble pyrrolopyrrole cyanine (PPCy) NIR fluorophores.

Water-soluble derivatives of pyrrolopyrrole cyanines (PPCys) have been synthesized by a post-synthetic modification route. In highly polar media, these dyes are excellent NIR fluorophores. Labeling experiments show how these novel dyes are internalized into mammalian cells.

Vibrational spectroscopic imaging and multiphoton microscopy of spinal cord injury.

Spinal cord injury triggers a series of complex biochemical alterations of nervous tissue. Up to now, such cellular events could not be studied without conventional tissue staining. The development of optical, label-free imaging techniques could provide powerful monitoring tools with the potential to be applied in vivo.

Photophysics of aminophenyl substituted pyrrolopyrrole cyanines.

A series of novel pyrrolopyrrole cyanines (PPCys) bearing various aminophenyl substituents at the diketopyrrolopyrrole (DPP) core are presented. Compared to their alkoxyphenyl substituted analogues, these dyes feature additional intense electronic transitions of charge-transfer character which give detailed insight into the optical properties of PPCys. The energetic mixing of the involved orbitals has pronounced effects on the absorption and fluorescence behavior.

Fast and long term lipid droplet tracking with CARS microscopy.

Photobleaching of organic fluorophores commonly used in fluorescence microscopy puts a limit to the number of images which can be acquired. Label-free imaging techniques therefore offer advantages both for rapid image acquisition and for long-term observations. CARS microscopy is a label-free imaging technique offering molecule specific contrast.