Fluorescent probes for the simultaneous detection of multiple analytes in biology

This review identifies and discusses fluorescent sensors that are capable of simultaneously reporting on the presence of two analytes for biological application.</p

A cobalt(II) complex with unique paraSHIFT responses to anions

A cobalt(ii) complex can distinguish between anions by observing the paramagnetic 1H NMR shift.</p

A ratiometric fluorescent sensor for the mitochondrial copper pool

Ratiometric probe for Cu(i) reveals influence of cisplatin on mitochondrial copper homeostasis.</p

Drawing on biology to inspire molecular design: a redox-responsive MRI probe based on Gd(iii)-nicotinamide

A novel, reversible redox-active MRI probe, GdNR1, has been developed for the study of redox changes associated with diseased states. This system exhibits switching in relaxivity upon reduction and oxidation of the appended nicotinimidium. Relaxivity studies and cyclic voltammetry confirmed the impressive reversibility of this system, at a biologically-relevant reduction potential. A 2.5-fold increase in relaxivity was observed upon reduction of the complex, which corresponds to a change in the number of inner-sphere water molecules, as confirmed by luminescence lifetimes of the Eu(iii) analogue and NMRD studies. This is the first example of a redox-responsive MRI probe utilising the biologically-inspired nicotinimidium redox switch. In the future this strategy could enable the non-invasive identification of hypoxic tissue and related cardiovascular disease.status: publishe

Nicotinamide-Appended Fluorophores as Fluorescent Redox Sensors

Fluorescent sensors have proved invaluable in elucidating the regulation and dysregulation of redox processes in biology, but understanding of the breadth of biological redox reactions requires development of new sensors based on a range of sensing groups with varied reduction potentials. The aim of this work was to investigate the use of nicotinamide as a redox switch when conjugated to two classes of amino-fluorophores. We prepared four fluorophore conjugates based on 7-aminocoumarins and 4-amino-1,8-naphthalimides via the nicotinamide Zincke salt. These conjugates all showed clear fluorescence changes in response to chemical reduction, but this reduction was irreversible both chemically and electrochemically. The reduction behaviour of the 1,8-naphthalimides was investigated further by spectroelectrochemistry, revealing that conjugate NNpR1 showed the clearest spectral changes upon both chemical and electrochemical reduction. Cells dosed with NNpR1 and maintained under hypoxic conditions exhibited a significantly higher green:blue fluorescence ratio than cells cultivated under normoxia, confirming the potential of this molecule as a sensor for reductive biological environments

TCAg1 supplementary information from A reversible fluorescent probe for monitoring Ag(I) ions

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Pro-fluorescent mitochondria-targeted real-time responsive redox probes synthesised from carboxy isoindoline nitroxides: Sensitive probes of mitochondrial redox status in cells.

Here we describe new fluorescent probes based on fluorescein and rhodamine that provide reversible, real-time insight into cellular redox status. The new probes incorporate bio-imaging relevant fluorophores derived from fluorescein and rhodamine linked with stable nitroxide radicals such that they cannot be cleaved, either spontaneously or enzymatically by cellular processes. Overall fluorescence emission is determined by reversible reduction and oxidation, hence the steady state emission intensity reflects the balance between redox potentials of critical redox couples within the cell. The permanent positive charge on the rhodamine-based probes leads to their rapid localisation within mitochondria in cells. Reduction and oxidation also leads to marked changes in the fluorophore lifetime, enabling monitoring by fluorescence lifetime imaging microscopy. Finally, we demonstrate that administration of a methyl ester version of the rhodamine-based probe can be used at concentrations as low as 5 nM to generate a readily detected response to redox stress within cells as analysed by flow cytometry

Respiratory syncytial virus co-opts host mitochondrial function to favour infectious virus production

© Hu et al. Although respiratory syncytial virus (RSV) is responsible for more human deaths each year than influenza, its pathogenic mechanisms are poorly understood. Here high-resolution quantitative imaging, bioenergetics measurements and mitochondrial membrane potential- and redox-sensitive dyes are used to define RSV’s impact on host mitochondria for the first time, delineating RSV-induced microtubule/dynein-dependent mitochondrial perinuclear clustering, and translocation towards the microtubule-organizing centre. These changes are concomitant with impaired mitochondrial respiration, loss of mitochondrial membrane potential and increased production of mitochondrial reactive oxygen species (ROS). Strikingly, agents that target microtubule integrity the dynein motor protein, or inhibit mitochondrial ROS production strongly suppresses RSV virus production, including in a mouse model with concomitantly reduced virus- induced lung inflammation. The results establish RSV’s unique ability to co-opt host cell mitochondria to facilitate viral infection, revealing the RSV-mitochondrial interface for the first time as a viable target for therapeutic intervention

28-09-2018-RA-eLife-42448_Source data

Source data including numerical data and image file