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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]

Subcellular microenvironment plays a crucial role in maintaining cell homeostasis being hydration an essential parameter to monitor the variations of lipid organization in biological membranes. Fluorescent microenvironment‐sensitive probes are stimuli‐responsive molecules and able to change their fluorescence profile according to the microenvironment properties (polarity, hydration, microviscosity and tension). Here we present an organic fluorescent probe, NPM‐1, as a new microenvironmental dye with selective plasma membrane localization in live cells. Using high‐resolution confocal microscopy and fluorescence spectroscopy, we explored the hydration and polarity variations during the formation of apoptotic bodies in real time. To have a clear understanding of the cell microenvironment variations, an analogue polarity probe able to localize the cytosol and nucleoli was also synthetized, CellPol‐1. Then, we were able to monitor the subcellular hydration variations during the apoptotic body dynamics. [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]

Local microviscosity monitoring in living cells is a powerful tool to determine their healthy status in either a specific organelle or in the cytosol. Here is presented the rational design of a new family of self-calibrating dual-microviscosity probes as a strategy to improve the probe response at low viscosity ranges. We found one of the probes is useful to determine low viscosity variations in living cells where subtle stiffening of the rotor group in the probe can increase its viscosity sensitivity. Further X-ray structure analysis, fluorescence anisotropic measurements, and quantum chemical calculations of the electronic excitation by means of a natural transition orbital (NTO) analysis confirmed the observed response. The present work demonstrates that small viscosity variations (0.01–0.1 cP) in cells require improved analytical sensitivity to be properly monitored. [ABSTRACT FROM AUTHOR]

Abstract: The measurement of physicochemical parameters in living cells can provide information on individual cellular organelles, helping us to understand subcellular function in health and disease. While organelle‐specific chemical probes have allowed qualitative evaluation of microenvironmental variations, the simultaneous quantification of mitochondrial local microviscosity (ηm) and micropolarity (ϵm), along with concurrent structural variations, has remained an unmet need. Herein, we describe a new multifunctional mitochondrial probe (MMP) for simultaneous monitoring of ηm and ϵm by fluorescence lifetime and emission intensity recordings, respectively. The MMP enables highly precise measurements of ηm and ϵm in the presence of a variety of agents perturbing cellular function, and the observed changes can also be correlated with alterations in mitochondrial network morphology and motility. This strategy represents a promising tool for the analysis of subtle changes in organellar structure. [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]

Fluorophore chemistry is at the forefront of bioimaging, revolutionizing the visualization of biological processes with unparalleled precision. From the serendipitous discovery of mauveine in 1856 to cutting-edge fluorophore engineering, this field has undergone transformative evolution. Today, the synergy of chemistry, biology, and imaging technologies has produced diverse, specialized fluorophores that enhance brightness, photostability, and targeting capabilities. This review delves into the history and innovation of fluorescent probes, showcasing their pivotal role in advancing our understanding of cellular dynamics and disease mechanisms. We highlight groundbreaking molecules and their applications, envisioning future breakthroughs that promise to redefine biomedical research and diagnostics. Conceptually innovative fluorophores represent groundbreaking molecules enabling precise and efficient cellular imaging. [Display omitted] • The evolution of fluorophores is traced from the 1856 discovery of mauveine to modern innovations in fluorophore engineering. • Synergistic advances in chemistry, biology, and imaging technologies yield specialized fluorophores with enhanced targeting. • Innovative fluorescent probes are introduced, highlighting groundbreaking molecules and their roles in cellular dynamics. • The revolution in fluorophore chemistry has transformed bioimaging, enabling precise visualization of biological processes. • Upcoming advances in fluorophore chemistry are analyzed, promising to redefine biomedical research and diagnostics. [ABSTRACT FROM AUTHOR]