Fluorescent small organic probes for biosensing

Small-molecule based fluorescent probes are increasingly important for the detection and imaging of biological signaling molecules due to their simplicity, high selectivity and sensitivity, whilst being non-invasive, and suitable for real-time analysis of living systems. With this perspective we highlight sensing mechanisms including Förster resonance energy transfer (FRET), intramolecular charge transfer (ICT), photoinduced electron transfer (PeT), excited state intramolecular proton transfer (ESIPT), aggregation induced emission (AIE) and multiple modality fluorescence approaches including dual/triple sensing mechanisms (DSM or TSM). Throughout the perspective we highlight the remaining challenges and suggest potential directions for development towards improved small-molecule fluorescent probes suitable for biosensing

Tunable ultranarrow linewidth of cavity induced by interacting dark resonances

A scheme for getting a tunable ultranarrow linewidth of a cavity due to an embedded four-level atomic medium with double-dark resonances is proposed. It is shown that the steep dispersion induced by double-dark resonances in the transparency window leads to the ultranarrow transmission peak. Compared with the case of a single-dark-resonance system, the linewidth can be narrowed even by one order under proper conditions. Furthermore, the position of the ultranarrow peak can be engineered by varying the intensity and detuning of the control field.Comment: 4 pages, 5 figure

Green Fluorescent Protein GFP-Chromophore-Based Probe for the Detection of Mitochondrial Viscosity in Living Cells

Viscosity is a pivotal factor for indicating the dysfunction of the mitochondria. To date, most of the fluorescent probes developed for mitochondrial viscosity have been designed using BODIPY, hemicyanine, or pyridine-based molecular rotors as part of the core structure. Our aim with this research was to extend the range of suitable fluorophores available for the construction of such fluorescent molecular rotors for evaluating the viscosity of mitocondria. Herein, we have developed a green fluorescent protein (GFP)-chromophore-based fluorescent probe (MIT-V) for the detection of mitochondrial viscosity in live cells. MIT-V exhibited a high sensitivity toward viscosity (from 7.9 cP to 438.4 cP). The "off-on"sensing mechanism of MIT-V was ascribed to the restricted rotation of single bonds and excited-state C= C double bonds of MIT-V. Cell studies indicated that MIT-V targets the mitochondria and that it was able to monitor real-time changes in the viscosity of live HeLa cell mitochondria. Therefore, we propose that MIT-V can be used as an effective chemosensor for the real-time imaging of mitochondrial viscosity in live cells. Our results clearly demonstrate the utility of such GFP-chromophore-based derivatives for the development of viscosity-sensitive systems.</p

Green Fluorescent Protein GFP-Chromophore-Based Probe for the Detection of Mitochondrial Viscosity in Living Cells

Viscosity is a pivotal factor for indicating the dysfunction of the mitochondria. To date, most of the fluorescent probes developed for mitochondrial viscosity have been designed using BODIPY, hemicyanine, or pyridine-based molecular rotors as part of the core structure. Our aim with this research was to extend the range of suitable fluorophores available for the construction of such fluorescent molecular rotors for evaluating the viscosity of mitocondria. Herein, we have developed a green fluorescent protein (GFP)-chromophore-based fluorescent probe (MIT-V) for the detection of mitochondrial viscosity in live cells. MIT-V exhibited a high sensitivity toward viscosity (from 7.9 cP to 438.4 cP). The "off-on"sensing mechanism of MIT-V was ascribed to the restricted rotation of single bonds and excited-state C= C double bonds of MIT-V. Cell studies indicated that MIT-V targets the mitochondria and that it was able to monitor real-time changes in the viscosity of live HeLa cell mitochondria. Therefore, we propose that MIT-V can be used as an effective chemosensor for the real-time imaging of mitochondrial viscosity in live cells. Our results clearly demonstrate the utility of such GFP-chromophore-based derivatives for the development of viscosity-sensitive systems.</p

Coumarin-based fluorescent probe for the detection of glutathione and nitroreductase

With this research we set out to develop a coumarin-based novel fluorescent probe NTR-AHC for the detection of biological thiols and nitroreductase (NTR). Probe NTR-AHC was constructed by attaching the NTR trigger moiety (p-nitrobenzyl) and biothiol acceptor (maleic acid monoamide), to the core fluorophore AHC. In the presence of both glutathione (GSH) and NTR, probe NTR-AHC produced a &gt;8-fold increase in fluorescence intensity at 463 nm

Coumarin-based fluorescent probe for the detection of glutathione and nitroreductase

With this research we set out to develop a coumarin-based novel fluorescent probe NTR-AHC for the detection of biological thiols and nitroreductase (NTR). Probe NTR-AHC was constructed by attaching the NTR trigger moiety (p-nitrobenzyl) and biothiol acceptor (maleic acid monoamide), to the core fluorophore AHC. In the presence of both glutathione (GSH) and NTR, probe NTR-AHC produced a &gt;8-fold increase in fluorescence intensity at 463 nm

Versatile Ratiometric Fluorescent Probe Based on the Two-Isophorone Fluorophore for Sensing Nitroxyl

Nitroxyl (HNO) is closely linked with numerous biological processes. Fluorescent probes provide a visual tool for determining HNO. Due to fluorescence quenching by HNO-responsive recognition groups, most of the current fluorescent probes exhibit an "off-on"fluorescence response. As such, the single fluorescence signal of these probes is easily affected by external factors such as the microenvironment, sensor concentration, and photobleaching. Herein, we have developed a ratiometric fluorescent probe (CHT-P) based on our previously developed two-isophorone fluorophore. CHT-P could be used to determine HNO through ratiometric signal readouts with high selectivity and sensitivity, ensuring the accurate quantitative detection of HNO. Additionally, the probe exhibited low cytotoxicity, was cell permeable, and could be used for ratiometric imaging of HNO in cells. Finally, CHT-P-coated portable test strips were used to determine HNO using the solid-state fluorescence signal readout. </p

Progress of fluorescent probes based on small organic molecules for pH value detection in biological systems

As traditional pH meters cannot work well for the real-time determination and quantitative detection of pH value changes in microenvironments (such as subcellular organelles) and complex biological systems,molecular pH-sensitive probes for monitoring pH changes in complicated and changeable biological systems are urgently needed.This review focuses on the current progress in small molecular fluorescence probes for the detection of pH value changes in biological systems (mainly in monitoring the pH fluctuation in the live cell).Future development of fluorescent probes for pH value detection in the biological systems was also discussed