A Fluorescent Chemodosimeter for Organelle-Specific Imaging of Nucleoside Polyphosphate Dynamics in Living Cells

Abstract

Nucleoside polyphosphates (NPPs) are mainly produced in mitochondria and used as a universal energy source for various cellular events. Although numerous fluorescent probes for adenosine triphosphate (ATP) have been reported, they are not ideally suited for live monitoring of the subtle variation of the mitochondrial ATP level. A new coumarin-based fluorescent probe is synthesized, and this reagent is utilized for specific recognition of NPPs in mitochondria by super-resolution microscopy in physiological condition. Detailed 31P NMR studies reveal that the probe, L·Zn­(II), binds to NPPs through their pendent phosphate functionalities. Such binding leads to a substantial enhancement in the luminescence intensity of L·Zn­(II) + ADP or L·Zn­(II) + ATP as compared to L·Zn­(II). Thisas well as 1H NMR spectroscopyhas enabled us to evaluate the probe’s binding affinities to these NPPs. Structured illumination and wide field fluorescence microscopy confirmed that this physiologically benign reagent is localized within mitochondria of live RAW 264.7 macrophage cells. This reagent has been utilized to probe real-time changes in ATP concentrations within mitochondria during drug-induced apoptosis.

Small Molecule as Fluorescent Probes for Monitoring Intracellular Enzymatic Transformations

“…Most luminophores with longer excitation/emission wavelength, specifically the NIR-active reagent, are generally highly conjugated organic derivatives and suffer from the problem of faster photobleaching on laser source irradiation during imaging studies. There is a distinct scope for exploring various physiologically benign inorganic metal complexes, specifically coordination complexes of certain lanthanide (Eu 3+ /Tb 3+ ) ions, graphene quantum dots, and Eu/Tb-based up-conversion nanoparticles for imaging application. , Many of these materials owing to their two-photon activity are also better suited for studying disease models with tissues and animals. In general, biological tissues strongly scatter light and this poses serious problem in recording high-resolution deep imaging even for confocal laser scanning microscopy.…”

Photoactive Lanthanide‐Based Upconverting Nanoclusters for Antimicrobial Applications

“…[ 137 ] Further, an UCNPs nanorod applicable for multimodal theranostics were also found to target specific organelle like mitochondria after the conjugating the former with mitochondria specific triphenylphosphonium cation. [ 138 ] In a nutshell, all these targeting strategies could, [ 139 ] in principle, be potentially translated into aPDT application against challenging drug‐resistant microbes. 4)As the majority of UCNPs‐based nanosystems or other nanomaterials meant for multimodal aPDT are developed while taking inspiration from antitumor therapy, their mere translation would be counter‐productive especially in design principles. The concept of photodynamic inactivation requires irradiation of cell with light having appropriate energy that causes the excitation of exogenous or endogenous photosensitizer molecules to yield ROS, which attributes to cell apoptosis.…”

Nanocarriers used as probes for super-resolution microscopy

“…3,6,7 As a consequence, optical microscopy has been a powerful and widely used technique for subcellular studies owing to its minimally invasive effects of light either on living cells and tissues for in-vivo studies. [8][9][10][11][12] However, until recently, this technology relied on discriminating objects through focusing, 13,14 and diffraction effects limit the application of such optical microscopy in achieving higher resolution. This phenomenon restricts the ability of conventional optical instruments to differentiate between two objects separated by a lateral distance that is less than the half of the wavelength of light used to image the objects.…”