Carbazole-Based Eu Complexes for Two-Photon Microscopy Imaging of Live Cells.

Lanthanide(III) complexes with two-photon absorbing antennas are attractive for microscopy imaging of live cells because they can be excited in the NIR. We describe the synthesis and luminescence and imaging properties of two Eu complexes, and , with (-carbazolyl)-aryl-alkynyl-picolinamide and (-carbazolyl)-aryl-picolinamide antennas, respectively, conjugated to the TAT cell-penetrating peptides. Contrary to what was previously observed with related Eu complexes with carbazole-based antennas in a mixture of water and organic solvents, these two complexes show very low emission quantum yield (Φ < 0.

Efficient cytosolic delivery of luminescent lanthanide bioprobes in live cells for two-photon microscopy.

Lanthanide(iii) (Ln) complexes have desirable photophysical properties for optical bioimaging. However, despite their advantages over organic dyes, their use for microscopy imaging is limited by the high-energy UV excitation they require and their poor ability to cross the cell membrane and reach the cytosol. Here we describe a novel family of lanthanide-based luminescent probes, termed dTAT[Ln·L], based on (i) a DOTA-like chelator with a picolinate moiety, (ii) a two-photon absorbing antenna to shift the excitation to the near infrared and (ii) a dimeric TAT cell-penetrating peptide for cytosolic delivery.

Tuning the Photophysical Properties of Aza-BODIPYs in the Near-Infrared Region by Introducing Electron-Donating Thiophene Substituents.

This study presents the synthesis, the spectroscopic and electrochemical properties of new bis- and tetra-substituted azaboron-dipyrromethene (aza-BODIPY) dyes substituted by different electron donating groups connected to the aza-BODIPY core through a thiophene unit. In line with theoretical calculations, experimental measurements point out the positive impact of the thiophene group that behave as a secondary donor group leading to an enhancement of the intramolecular charge transfer process in comparison to previously reported aza-BODIPY dyes. This heterocycle has also been found to tune the oxidative potential and to stabilize the electro-generated species.

Domes and semi-capsules as model systems for infrared microspectroscopy of biological cells.

It is well known that infrared microscopy of micrometer sized samples suffers from strong scattering distortions, attributed to Mie scattering. The state-of-the-art preprocessing technique for modelling and removing Mie scattering features from infrared absorbance spectra of biological samples is built on a meta model for perfect spheres. However, non-spherical cell shapes are the norm rather than the exception, and it is therefore highly relevant to evaluate the validity of this preprocessing technique for deformed spherical systems.

Assembly of Aggregation-Induced Emission Active Bola-Amphiphilic Macromolecules into Luminescent Nanoparticles Optimized for Two-Photon Microscopy In Vivo.

The (Z) and (E)-isomers of an extended tetraphenylethylene-based chromophore with optimized two-photon-induced luminescence properties are separated and functionalized with water-solubilizing pendant polymer groups, promoting their self-assembly in physiological media in the form of small, colloidal stable organic nanoparticles. The two resulting fluorescent suspensions are then evaluated as potential two-photon luminescent contrast agents for intravital epifluorescence and two-photon fluorescence microscopy. Comparisons with previously reported works involving similar fluorophores devoid of polymer side chains illustrate the benefits of later functionalization regarding the control of the self-assembly of the nano-objects and ultimately their biocompatibility toward the imaged organism.