Search

This study introduces a paradigm-shifting approach to optimize mitochondrial targeting. Employing a new fluorescent probe strategy, we unravel a combined influence of both Nernst potential (ψ) and partitioning (P) contributions. Through the synthesis of new benz[e]indolinium-derived probes, our findings redefine the landscape of mitochondrial localization by optimizing the efficacy of mitochondrial probe retention in primary cortical neurons undergoing normoxia and oxygen--glucose deprivation. This methodology not only advances our understanding of subcellular dynamics, but also holds promise for transformative applications in biomedical research and therapeutic development. [ABSTRACT FROM AUTHOR]

Mitochondrial voltage dynamics plays a crucial role in cell healthy and disease. Here, a new fluorescent probe to monitor mitochondrial early voltage variations is described. The slowly permeant probe is retained in mitochondria during measurements to avoid interferences from natural membrane potential by incorporating an hydrolizable ester function. Voltage, local polarity, pH parameters and transmembrane dynamics were found to be deeply correlated opening a approach in mitochondrial sensing. [ABSTRACT FROM AUTHOR]

Small-molecule fluorescent probes having optimized optical properties, such as high photostability and brightness, local microenvironment sensitivity and specific subcellular localizations, are increasingly available. Although the basis for designing efficient fluorophores for bioimaging applications is well established, implementing an improvement in a given photophysical characteristic always tends to compromise another optical property. This problem has enormous consequences for in vivo imaging, where ensuring a specific localization and precise control of the probe response is challenging. Herein we discuss a fluorescent probe, CC334, as a case study of the chromenylium-cyanine family that commonly exhibits highly complex photophysical schemes and highly interfered bioanalytical responses. By an exhaustive and concise analysis of the CC334 optical responses including detailed spectroscopic calibrations, steady-state microenvironment effects, ultrafast photophysics analysis and computational studies, we elucidate a new strategy to apply the probe in the singlet oxygen reactive oxygen species (1O2-ROS) monitoring using in vitro and in vivo models. The probe provides a new avenue for designing fluorescent probes to understand the dynamic behavior of subcellular environments. [ABSTRACT FROM AUTHOR]

A dual-emissive fluorescent probe enabling dynamic changes in nuclear local microviscosity monitoring was developed. The new sensing scenario involves probe subcellular localization redistribution, allowing a quantitative analysis of the local microviscosity related to nuclear damage in the presence of agents perturbing the nuclear morphology. With the aid of an organotin(iv) in situ formed complex we propose a different scenario of bioanalytical applications through confocal microscopy. [ABSTRACT FROM AUTHOR]

The dual-emissive fluorescent probe described here enabled dynamic tracking of singlet oxygen (1O2)-ROS species production and localization dynamics between the mitochondria and nucleoli in the presence of agents perturbing the mitochondrial membrane potential and under a photodynamic (PDT) system. Local structural information during the probe-1O2 interaction was followed by spectrally resolved confocal microscopy. [ABSTRACT FROM AUTHOR]

Non-classical protomerism of Schiff bases offers several advantages; for example, specific interactions in the –C=N– linkage can be controlled and differentiated because the interactions are not governed by keto–enol tautomerism. Herein, the pH sensing properties of a new protomeric Schiff base probe (S1) are reported. In particular, among several acids, the probe displays significant optical responses upon interaction with hydrochloric acid (HCl). X-ray structural analysis confirmed the existence of an intermolecular interaction with HCl through a –C=N…H–Cl…O– linkage. Moreover, an optical response via a second channel is manifested as photochromic fluorescence behavior. The properties of S1 were investigated by UV-vis and fluorescence spectroscopy in a solution and the solid state. Its strong acidofluorochromic behavior was analyzed and its pKa and UGRAPHIC DISPLAY="INLINE" ID="UGT1" SRC="UGT1"/ values were determined, which revealed a photobasic character. Positive solvatochromism that resulted from specific interactions taking place in S1 was studied using four different solvent scales, namely, Lippert–Mataga, Kamlet–Taft, Catalán and the recently proposed scale of Laurence et al., which yielded consistent results. Finally, theoretical calculations were conducted to analyze the mechanism of the probe in terms of natural transition orbitals (NTOs) and the spatial extent of charge transfer excitations. [ABSTRACT FROM AUTHOR]

BODIPY-derived molecular fluorescent rotors are one of the most useful families of fluorescent probes for the quantitative measurement of microviscosity. Here, we report the photophysical properties of two molecular rotors as ratiometric viscosity sensors, meso-(4-(9H-fluoren-2-yl)ethynyl)phenyl-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (1) and meso-(5-(9H-fluoren-2-yl)ethynyl)thiophen-2-yl-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (2) having two independent chromophores; one (fluorene) is not influenced by viscosity and is used to determine concentration properties, and the other chromophore (BODIPY) acts as a molecular rotor. The fluorescence ratiometric calibration against microviscosity for the most sensitive probe (1), was obtained in a wide linear dynamic range. The sensitivity of the spectroscopic observables for 1 and 2 towards solvent viscosity and the typical analytical interfering solvent polarity and polarizability parameters were investigated by means of two different solvent scales, namely Lippert–Mataga and Catalán, finding consistent results. Quantum chemical calculations were conducted to analyze the probe mechanism in terms of Natural Transition Orbitals (NTOs) and the spatial extent of charge transfer excitations. [ABSTRACT FROM AUTHOR]

Two simple and low cost 2,4-di-tert-butyl-6-[(1-hydroxycyclohexylmethylimino)methyl]phenol (L1) and 2-[{(1-hydroxycyclohexyl)methylimino}methyl]phenol (L2) Schiff base sensors exhibiting selectivity for Zn2+ in water : methanol (95 : 5, v/v, 10 mM HEPES) are described. L1 and L2 display an “off–on” fluorescence effect forming the L1·Zn and L2·Zn complexes, respectively. In the case of L1·Zn, the emission response is quenched by the addition of Cu2+ forming the respective L1·Cu complex; in spite of that, the fluorescence signal can be completely restored only by the addition of tartrate anions (C4H4O62−) forming again L1·Znvia the “off–on” displacement approach. However, in the case of L2·Zn no Cu2+ interference is observed, which is a typical problem for Zn2+ sensors. Here we describe that a very subtle structural change in the ligand during transition from the enol-imine tautomer in L1 to the keto-enamine tautomer in L2 is enough to modulate the Zn2+/Cu2+ selectivity. Also, the Zn2+vs. Cd2+ discrimination for L1 and L2 is proved. Moreover, we found that the interaction between both L·Zn complexes and tartrate anions completely restored the free ligands by the ligand substitution mechanism even in a more efficient association than phosphate anions. Further, a second colorimetric response channel upon addition of Fe2+ was observed for L1 and L2. Then, TD-DFT theoretical calculations were conducted in order to study the efficiency of the sensors to give different responses in the presence of such metal ions. Finally, the L2 sensor successfully detects Zn2+ in Jurkat cells cultured with and without Zn2+ enriched medium. [ABSTRACT FROM AUTHOR]

Seven Schiff base derivatives of 4-dimethylamino-trans-cinnamaldehyde were synthesized in good yield. The structures of all new derivatives were established by IR, 1H, 13C NMR and HRMS experiments and three of them were corroborated by X-ray diffraction studies. Analysis of the supramolecular structures evidenced the presence of strong intermolecular hydrogen bonds (O–H…N) which promote the formation of molecular chains. The linear properties of this series of chromophores were investigated by UV-Vis and fluorescence spectroscopy in solution and in the solid state. The results revealed interesting photochromic properties for compound 2a promoted by a hydrogen bonding interaction in the solid state, which was established by absorption and emission spectra. Further evidence of the specific interactions that take place in compound 2a was obtained by studying the solvent effects observing a solvato- and acidochromic behavior. [ABSTRACT FROM AUTHOR]

The dual-emissive fluorescent probe described here enabled dynamic tracking of singlet oxygen (1O2)-ROS species production and localization dynamics between the mitochondria and nucleoli in the presence of agents perturbing the mitochondrial membrane potential and under a photodynamic (PDT) system. Local structural information during the probe-1O2 interaction was followed by spectrally resolved confocal microscopy.

Two simple and low cost 2,4-di-tert-butyl-6-[(1-hydroxycyclohexylmethylimino)methyl]phenol (L1) and 2-[{(1-hydroxycyclohexyl)methylimino}methyl]phenol (L2) Schiff base sensors exhibiting selectivity for Zn(2+) in water:methanol (95:5, v/v, 10 mM HEPES) are described. L1 and L2 display an "off-on" fluorescence effect forming the L1·Zn and L2·Zn complexes, respectively. In the case of L1·Zn, the emission response is quenched by the addition of Cu(2+) forming the respective L1·Cu complex; in spite of that, the fluorescence signal can be completely restored only by the addition of tartrate anions (C4H4O6(2-)) forming again L1·Znvia the "off-on" displacement approach. However, in the case of L2·Zn no Cu(2+) interference is observed, which is a typical problem for Zn(2+) sensors. Here we describe that a very subtle structural change in the ligand during transition from the enol-imine tautomer in L1 to the keto-enamine tautomer in L2 is enough to modulate the Zn(2+)/Cu(2+) selectivity. Also, the Zn(2+)vs. Cd(2+) discrimination for L1 and L2 is proved. Moreover, we found that the interaction between both L·Zn complexes and tartrate anions completely restored the free ligands by the ligand substitution mechanism even in a more efficient association than phosphate anions. Further, a second colorimetric response channel upon addition of Fe(2+) was observed for L1 and L2. Then, TD-DFT theoretical calculations were conducted in order to study the efficiency of the sensors to give different responses in the presence of such metal ions. Finally, the L2 sensor successfully detects Zn(2+) in Jurkat cells cultured with and without Zn(2+) enriched medium.