Fluorescence Intensity Of Probe Research Articles

Detecting viscosity changes in the limb ischemia-reperfusion in mice with a near-infrared fluorescence probe

BackgroundLimb ischemia-reperfusion is a common phenomenon in clinical surgery, which disrupts the balanced physiological response process and ultimately leads to changes in intracellular viscosity. Intracellular viscosity is an important microenvironmental parameter that affects the normal function of organisms, and its level is closely related to many diseases. In addition, oxidative stress in the lower limbs can impair body function, and changes in pressure can lead to changes in the viscosity of limb tissues. Therefore, it is necessary to develop effective tools to detect changes in intracellular viscosity and visualize the progression of hind limb ischemia-reperfusion injury. ResultsIn order to solve this problem, a near infrared viscometry sensitive fluorescence probe (PH-XQ) with long emission wavelength and stable luminescence performance was designed and synthesized by using oxanthracene derivatives and malononitrile. The fluorescence probe (PH-XQ) has excellent selectivity, high sensitivity, low toxicity, high biocompatibility and excellent detection performance. The fluorescence intensity of the PH-XQ probe at 667 nm is highly sensitive to the change of viscosity. With the increase of viscosity, the fluorescence intensity of probe PH-XQ was significantly enhanced, and the fluorescence enhancement ratio was about 14-fold. In addition, PH-XQ can detect not only changes in viscosity between normal cells and drug-induced inflammatory cells, but also changes in the viscosity of the hind limbs of normal mice and mice after ischemia reperfusion. SignificanceIn particular, we are the first to successfully detect changes in handlimb viscosity after ischemia-reperfusion in mice using a probe. This study clearly elucidates changes in viscosity during ischemia-reperfusion of mouse limbs, providing favorable support for the relationship between viscosity and related diseases, and further providing a potential tool for the diagnosis of viscosity-related diseases.

Coumarin-based fluorescent probe synthesized by one-step reaction for sensitive detection of hydrazine and its application

Abstract A coumarin-derivative fluorescent probe 3-(2-naphthyl)-7-acetoxycoumarin (TTAM) for hydrazine detection was successfully designed and synthesized. Hydrogen nuclear magnetic resonance (1H NMR) spectroscopy and high-resolution mass spectrometry showed that the nucleophilic substitution that occurred between hydrazine and the acyl oxide group of TTAM led to the probe fluorescence intensity increasing significantly and a remarkable color change that could be distinguished by using the naked eye. The reaction could be finished in 120 s and the detection limit was only 3.1 × 10−8 M. Moreover, a simple test paper was successfully developed that could be applied for the rapid detection of hydrazine in water samples.

Cucurbit[8]uril-Based Supramolecular Probe for the Detection of 3-Nitrotyrosine in Human Serum and Plasma.

The biomarker 3-nitrotyrosine (3-NT) is widely recognized as an indicator of renal oxidative stress injury, making its detection crucial for the early identification of renal insufficiency. This study presents the design and synthesis of a tetraphenylstyrene imidazole derivative (TIPE-MI), which is utilized to create a supramolecular probe in conjunction with cucurbit[8]uril (Q[8]) through host-guest interactions. The resulting supramolecular self-assembly exhibits excellent optical properties and has been employed for the specific detection of 3-NT through fluorescence quenching. The introduction of 3-NT resulted in a decreased fluorescence intensity of the yellow fluorescent probe, which gradually transitioned from bright yellow to light yellow and then became colorless as the 3-NT concentration was increased. A portable detection platform was devised to augment the efficiency of detection. In order to facilitate biological applications, we have substantiated the probe's exceptional precision in detecting 3-NT in biological samples, encompassing human serum and plasma. The probe also exhibited negligible cytotoxicity. The accumulation of the probe in renal cells elicited a fluorescence signal, thereby indicating the prospective viability of this system for visual detection with renal cytocompatibility.

Singlet Oxygen Detection by Chemiluminescence Probes in Living Cells.

Singlet oxygen is a reactive oxygen species that causes oxidative damage to plant cells, but intriguingly it can also act as a signalling molecule to reprogram gene expression required to induce plant physiological/cellular responses. Singlet oxygen photosensitization in plants mainly occurs in chloroplasts after the molecular collision of ground-state molecular oxygen with triplet-excited-state chlorophyll. Singlet oxygen direct detection through phosphorescence emission in chloroplasts is a herculean task due to its extremely low luminescence quantum yield. Because of this, indirect alternative methods have been developed for its detection in biological systems, for example, by measuring the changes in the EPR signal or fluorescence intensity of singlet oxygen reaction-based probes. The singlet oxygen chemiluminescence (SOCL) is a chemiluminescence probe with high sensitivity and selectivity towards singlet oxygen and promising use to detect it in living cells without the inconvenience of low stability of the EPR signal of spin probes in the presence of redox compounds, spurious light scattering coming from the light source required for the excitation of fluorescence probes or the light emission of endogenous fluorescent molecules like chlorophyll in chloroplasts. The protocol presented in this chapter describes the first steps to characterizing singlet oxygen production within the biological system under study; this is accomplished through monitoring molecular oxygen consumption by SOCL using a Clark-type oxygen electrode and measuring the chemiluminescence generated by SOCL 1,2-dioxetane using a spectrofluorometer. For singlet oxygen detection within living cells, a version of SOCL with increased membrane permeability (SOCL-CPP) is described.

Construction and Application of Fluorescent Probes with Imine Protective Groups for Hypochlorite Detection.

Several fluorescent probes have been designed to detect ClO- in biological systems based on the isomerization mechanism of C = N bonds. Particularly, fluorescein has emerged as an important fluorophore for detecting ClO- because of its unique properties. Previously, we introduced the fluorescein analog F-1 with an active aldehyde group. In this study, two ClO- fluorescent sensors (F-2 and F-3) with imine groups were designed and synthesized using diaminomaleonitrile and 2-hydrazylbenzothiazole as amines. The electron cloud distribution of F-2 and F-3 in ground and excited states was explored via Gaussian calculations, reasonably explaining their photophysical properties. The fluorescence detection of ClO- in solution using the two probes (F-2 and F-3) was realized based on the mechanism of imine deprotection with ClO-. NaClO concentration titration demonstrated that the colorimetric detection of ClO- with the naked eye could be achieved using both F-2 and F-3. However, after adding ClO-, the fluorescence intensity of probe F-2 increased, whereas that of probe F-3 first decreased and then increased. Probes F-2 and F-3 exhibited good selectivity, anti-interference capability, and sensitivity, with the detection limits of 169.95 and 37.30 µM, respectively. Owing to their low cell toxicity, probes F-2 and F-3 can be applied to detect ClO- in vivo. The design approach adopted in this study will further advance the future development of ClO- chemical probes through the removal of C = N bond isomerization.

A Fluorescent Benzothiazole Probe for the Detection of Carboxylesterase and Carbamate Pesticides

AbstractA benzothiazole fluorescent probe (probe 1) was developed for the determination of carboxylesterase and carbamate pesticides. The probe used benzothiazole as the fluorescent group and chlorophenyl acetate as the recognition group. The recognition mechanism of probe 1 for carboxylesterase was based on the enzymatic hydrolysis of chlorophenyl acetate by carboxylesterase. The solution of probe 1 gradually changed from light blue to dark blue as the concentration of carbamate pesticide increased. Probe 1 could detect the concentration of carbamate pesticide based on the linear functional relationship between the R/B*G (red, blue, green) value of the probe 1 solution photo and the concentration of carbaryl without professional personnel and equipment. Additionally, probe 1 was successfully used to detect the concentration of carbaryl in actual samples based on the curve function relationship between the fluorescence intensity of probe 1 at 434 nm and the concentration of carbaryl.

Pyrene based Schiff base ligand: A highly selective fluorescence chemosensor for the detection of Cu2+ ions

A Schiff base ligand L has been designed and synthesized by the condensation of 1′-Hydroxy-2′-acetonaphthonehydrazide with pyrene aldehyde for the detection of Cu2+ ions. The ligand was spectroscopically characterized by all possible techniques. Among different metal ions, Cu2+ ions give a tremendous enhancement of fluorescence intensity in 20% water with THF. The “Turn-On” fluorescence for Cu2+ ions utilizes the Photo-induced Electron Transfer (PET) mechanism. It has been observed that the presence of relevant cations and anions did not affect the probe's fluorescence intensity. The stoichiometric binding mode of the complex is confirmed using Job's method. The low detection limit and reversibility make it cost-effective.

Empagliflozin attenuates the renal tubular ferroptosis in diabetic kidney disease through AMPK/NRF2 pathway.

Renal tubular damage plays a key role in the pathogenesis of diabetic kidney disease (DKD), and one of the main pathological process associated with DKD in diabetic mice is the ferroptosis, a novel form of cell death caused by iron-dependent lipid peroxidation. Several researches suggested that empagliflozin may treat renal injury, but its effects on diabetic-related ferroptosis and underlying mechanisms were not fully elucidated. In this study, the influence of empagliflozin on renal injury was evaluated in vivo and in vitro in a mouse model and in high-glucose (HG) or Erastin-stimulated renal HK-2cell line, respectively. Ferroptosis-related markers were assessed, including GSH, labile iron levels, and ferroptosis regulators by Western blot, qRT-PCR, immunohistochemistry, and immunofluorescence. The level of malondialdehyde (MDA) and the fluorescence intensity of BODIPY probe indicated the level of lipid peroxidation. It was demonstrated that solute carrier family 7, member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) were less expressed in renal biopsy samples from patients affected by DKD than in those from non-diabetic renal disease patients (NDRD), proving the ferroptosis of tubular epithelial cells in case of DKD. Furthermore, empagliflozin markedly decreased the ferroptosis impairment in DKD mice, as well as in HG model of HK-2cells. Our investigations showed the ability of empagliflozin to suppress ferroptosis was partially countered by AMP-activated protein kinase (AMPK) inhibitor, which led to a reduction of the nuclear translocation of the antioxidant transcription factor NFE2-related factor 2 (NRF2) and downregulation of target genes such as GPX4, ferritin heavy chain 1 (FTH1), and SLC7A11, while AMPK agonists were responsible for the enhancement of the protective effects of empagliflozin. Taken together, our findings showed that empagliflozin may prevent the development of ferroptosis by promoting the AMPK-mediated NRF2 activation pathway, providing important insights for possible novel treatment approaches for DKD.

1, 10-phenanthroline derivative as colorimetric and ratiometric fluorescence probe for Zn2+ and Cd2+

A colorimetric and ratiometric fluorescent probe 2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline (probe 1), was designed and synthesized for sensitive and selective detection of Zn2+ and Cd2+ ions in methanol, test paper and actual water samples. When probe 1 was excited at 350 nm in methanol solution, in the presence of alkali metal ions, alkali-earth metal ions and a variety of transition metal ions, it showed sensitive fluorescence selectivity to Zn2+ and Cd2+ ions. With the addition of Zn2+, the color of the solution changed from purple to cyan with the naked eye, and with the addition of Cd2+, the color of the solution changed from purple to blue. The fluorescence intensity of probe 1 showed a good linear relationship with Zn2+ and Cd2+ concentrations, and the detection limits were 0.04 μM and 0.11 μM, respectively. The binding mode of probe 1 and Cd2+ was discussed according to the 1-Cd single X-ray crystal structure. In addition, the results of strip test and real water sample test showed that probe 1 has potential application in environmental metal ion recognition and detection.

Phenanthroline-based ligand scaffold as an efficient colorimetric and ratiometric fluorescence probe for Zn2+ and Cd2+ ion detection

A colorimetric and ratiometric fluorescent probe 2-(naphthalen-2-yl)-2,11b-dihydro-1H-imidazo[4,5-f][1,10]phenanthroline (probe 1), was designed and synthesized for sensitive and selective detection of Zn2+ and Cd2+ in methanol, test paper and actual water samples. When probe 1 was excited at 350 nm in methanol solution, in the presence of alkali metal ions, alkali-earth metal ions and a variety of transition metal ions, it showed sensitive fluorescence selectivity to Zn2+ and Cd2+. With the addition of Zn2+, the color of the solution changed from purple to green with the naked eye, and with the addition of Cd2+, the color of the solution changed from purple to cyan. The fluorescence intensity of probe 1 showed a good linear relationship with Zn2+ and Cd2+ concentrations, and the detection limits were 0.09 μM and 0.06 μM, respectively. The binding mode of probe 1 and Zn2+ was discussed according to the 1-Zn single X-ray crystal structure. In addition, the results of strip test and real water sample test showed that probe 1 has potential application in environmental metal ion recognition and detection.

Luminescent Pyrene-based Schiff base Receptor for Hazardous Mercury(II) Detection Demonstrated by Cell Imaging and Test Strip.

Qualitative and quantitative analysis of mercury at concentration levels as low as parts per billion (ppb) is a basic and practical concern. The vast majority of research in this field has centered on the development of potent chemosensor to monitor mercuric (Hg2+) ions. Mercury exists in three oxidation states, + 2, + 1 and 0, all of which are highly poisonous. In this study, (N1E,N2E)-N1,N2-bis(pyrene-1-ylmethylene)benzene-1,2-diamine (PAPM), a novel photoluminescent sensor based on pyrene platform was synthesized. Over the tested metal ions (Cd2+, Co2+, Cu2+, Mg2+, Mn2+, Ni2+, K+, Na+, Zn2+, Sr2+, Pb2+, Al3+, Cr3+ and Fe3+) the sensor responds only to Hg2+ by showing high selectivity and sensitivity. After treatment with mercuric ions at room temperature, the luminescence intensity of probe was quenched at 456nm. The quenching of fluorescence intensity of probe upon addition of mercury is due to the effect of "turn-off" chelation enhanced quenching (CHEQ) by the formation of 1:1 complex. The ESI-MS spectrum and the Job's experimental results confirm the formation of 1:1 complex between PAPM and Hg2+. The detection limit and association constant of sensor for mercury is computed using fluorescence titration data and were found to be 9.0 × 10-8M and 1.29 × 105M-1 respectively. The practical application of sensor towards recognition of mercury(II) ions was explored through economically viable test strips and also using cell imaging studies.

PH/Viscosity dual-response fluorescent probes as highly selective tumor visualization tools

Due to the complexity of physiological environment and the small changes of related parameters, it is difficult for a single-mode fluorescent probe to achieve excellent and accurate detection. In this paper, two dual-mode fluorescent probes responding to both pH and viscosity were designed and synthesized based on inhibited intramolecular charge transfer (ICT) and twisted intramolecular charge transfer (TICT) processes. At low pH and high viscosity, the fluorescence intensity of probes would be doubly amplified, providing excellent contrast for biological imaging. The wavelength of CL-2 was redshifted by 45 nm for better penetration by extending the conjugated system of CL-1. Fluorescence imaging in living cells, tissue and organs further illustrated that the probes synthesized in this paper could selectively realize the visualization of cancer.

Air fine particulate matter induced alveolar type Ⅱ epithelial cell injury in rats

To investigate the damage of rat alveolar type II epithelial cells(RLE-6 TN) caused by air fine particulate matter(PM_(2.5)) and its related mechanism. PM_(2.5) in the atmosphere of Weifang City in 2020 was collected and cell culture medium was used to prepare particulate suspension. RLE-6 TN cells were exposed to different concentrations(25, 50, 100, 200, 400 μg/mL) of particulate matter suspensions for 24 h. The morphological changes of RLE-6 TN cells were observed under inverted microscope, and the cell viability was determined by MTT method. The concentration of lactate dehydrogenase(LDH) in cell supernatant was determined by microplate method. DCFH-DA, Annexin V-FITC/PI, JC-1 probe and laser confocal fluorescence intensity were used to determine the levels of reactive oxygen species(ROS), apoptosis and mitochondrial membrane potential. Total superoxide dismutase(T-SOD), glutathione(GSH) and malondialdehyde(MDA) contents and activity levels in cells were determined by colorimetric method. Caspase-3 and Caspase-9 kit were used to detect the relative expression activity of apoptosis proteins. PM_(2.5) could lead to morphological changes of RLE-6 TN cells, enlarged cell space and decreased cell viability. Compared with the control group, there were statistically significant differences in each dose group(P<0.05). LDH concentration in the supernatant of ≥50 μg/mL infected group increased, and LDH concentration was ≥(377.82±29.84), which was significantly different from that of the control group(278.51±23.76)(P<0.05). The result of laser confocal detection of ROS showed that the intracellular green fluorescence increased gradually in the ≥50 μg/mL group, and the relative fluorescence intensity was ≥(2.77±0.18), which was statistically significant compared with the control group(P<0.05). The level of apoptosis was significantly increased compared with the control group(P<0.05). The level of mitochondrial membrane potential decreased gradually, and the level of mitochondrial membrane potential in the ≥25 μg/mL group was ≤(4.22±0.45), which was statistically different from that in the control group(6.16±0.49)(P<0.05). PM_(2.5) could reduce the levels of T-SOD and GSH, and the levels of T-SOD and GSH in ≥50 μg/mL exposed group were ≤(14.67±0.49) and ≤(433.29±39.24), respectively, significantly lower than those in control group((16.58±0.60) and(542.90±45.06))(P<0.05). MDA level increased with the increase of PM_(2.5) concentration. Compared with the control group(1.15±0.19), MDA level in ≥50 μg/mL exposed group was ≥(1.72±0.13), with statistical significance(P<0.05). The activity levels of Caspase-3 and Caspase-9 increased in ≥100 μg/mL group, and the activity levels were ≥(1.62±0.27) and ≥(1.23±0.06), respectively, compared with the control group, the differences were statistically significant(P<0.05). Exposure to a certain concentration of PM_(2.5) can induce oxidative stress of rat alveolar type II epithelial cells, reduce the membrane potential, and eventually lead to cell apoptosis.

A colorimetric and ratiometric fluorescence probe for Zn2+ and Cd2+ with 1,10-phenanthroline derivative

A colorimetric and ratiometric fluorescent probe 2-([1, 1′-biphenyl]-4-yl)-2, 3b,11a,11b-tetrahydro-1H-imidazo[4,5-f][1,10]phenanthroline (probe 1), was designed and synthesized for sensitive and selective detection of Zn2+ and Cd2+ in methanol, test paper and actual water samples. When probe 1 was excited at 350 nm in methanol solution, in the presence of alkali metal ions, alkali-earth metal ions and a variety of transition metal ions, it showed sensitive fluorescence selectivity to Zn2+ and Cd2+. With the addition of Zn2+, the color of the solution changed from purple to green with the naked eye, and with the addition of Cd2+, the color of the solution changed from purple to cyan. The fluorescence intensity of probe 1 showed a good linear relationship with Zn2+ and Cd2+ concentrations, and the detection limits of both Zn2+ and Cd2+ were 0.11 μM. The binding mode of probe 1 and Zn2+ was discussed according to the 1-Zn single X-ray crystal structure. In addition, the results of strip test and real water sample test showed that probe 1 has potential application prospect in environmental ion recognition.

Ionic thermoresponsive fluorescent polymers for detecting countercharged surfactants without phase separation

Thermoresponsive polymers containing ionic and fluorescent groups were designed and synthesized for use as fluorescent probes to sense ionic surfactants without phase separation. The synthesized ionic thermoresponsive fluorescent polymers interact with countercharged surfactants, resulting in increases in their fluorescence intensities, even at temperatures lower than their phase-transition temperatures. The observed increases in the fluorescence intensities are attributable to the incorporation of fluorophores within the soluble aggregates formed by the polymers and ionic surfactants at temperatures lower than the phase-transition temperatures. The synergistic effects of the hydrophobic and ionic interactions between the two moieties lead to the formation of soluble aggregates, which enhance the fluorescence of the fluorophores bound to the polymers. The fluorescence intensities of cationic and anionic fluorescent polymer probes were found to be linearly dependent on the concentrations of sodium dodecyl sulfate (SDS) and zephilamine, respectively, at the 10−5 mol/L level. Moreover, the concentration of SDS, an anionic surfactant used commonly in detergents, as determined using the cationic fluorescent probe was in keeping with that determined by the conventional methylene blue method. Thus, it was confirmed that the synthesized thermoresponsive fluorescent polymers with ionic groups can function as probes for countercharged ionic surfactants in homogeneous aqueous media without any phase-separation processes, which require hazardous organic solvents.

The location of octenyl succinate anhydride groups in high-amylose maize starch granules and its effect on stability of pickering emulsion stability

Octenyl succinate anhydride (OSA) modified high amylose maize starch (HAMS) showed limited emulsion stability due to the OSA groups were located on the surface of starch granules. However, amylose is enriched in the internal region of HAMS and provides the reaction site for OSA groups. In this study, five types of starches with different amylose content were prepared using optimized reaction conditions. Our data showed that amylose content (AC) was the most important parameter controlling the degree of substitution (DS), in comparison with temperature, pH, starch concentration and time. DS reached a maximum (2.1%) at AC of 58%. Importantly, OSA groups were mainly located in the internal regions of HAMS under the optimized reaction conditions. This was supported by (1) the decrease of the crystallinity, (2) the weaker fluorescence intensity of the starch fluorophore probe 8-amino-1,3,6-pyrenetrisulfonic acid (APTS) in the internal regions of HAMS, and (3) unchanged signals from Fourier transform infrared spectroscopy which characterized the granular surface structure ordering. This new OSA reaction pattern permits HAMS to be used in stabilizing Pickering emulsions This is the first report that OSA groups located in the internal regions of HAMS granules.

Label-free hairpin probe for the rapid detection of Hg(II) based on T-Hg(II)-T

A simple thymine-rich mercury-specific oligonucleotide (G9T24C9) was designed to quickly detect Hg(Ⅱ) via thymine-Hg(II)-thymine (T-Hg(Ⅱ)-T) coordination chemistry by using 4′,6-diamidinyl-2-phenylindole (DAPI). When the stable GC-paired stem of the DNA hairpin occurred, DPAI could intercalate into the T-Hg(Ⅱ)-T base pairs as a fluorescent recognizer. As a result, the hairpin structure was able to promote the rapid formation of T-Hg(Ⅱ)-T mismatches in the presence of Hg(Ⅱ), trigger DAPI to recognize T-Hg(Ⅱ)-T as well as TA/AT base pairs and restore fluorescence; moreover, fluorescence increases were not observed when Hg(Ⅱ) was not introduced. This method represents a simple strategy to detect Hg(Ⅱ). Taking advantage of the hairpin structure, the fluorescence intensity of the G9T24C9 hairpin probe was positively correlated with the concentration of Hg(Ⅱ) from 2.87 to 1400 nM (R2 = 0.9968), and the limit of detection (3σ) was as low as 2.87 nM. Furthermore, this probe had high selectivity for Hg(Ⅱ) detection. The probe was applied to real samples of pond water for the detection of Hg(Ⅱ), and a recovery rate from 95.9% to 104.4% was obtained.

A “Turn-On” fluorescent probe for detection and removal of Zn2+ in aqueous and its application in living cells

Using 3-hydroxy-2-naphthoic acid hydrazine and 4-(diethylamino) salicylaldehyde.as raw materials, compound L with an acylhydrazones structure was synthesized. The structure of compound L was characterized by nuclear magnetic resonance spectroscopy, X-ray single crystal diffraction, Fourier transform infrared spectroscopy, and mass spectrometry. The results show that Compound L can quickly and selectively recognize zinc ions in the H2O/DMSO (V:V = 3:7) solvent system. After that, the spectral performance of probe L was studied by fluorescence spectroscopy and UV–vis spectroscopy. The results show that the combination with Zn2+ can significantly enhance the fluorescence intensity of probe L while being almost unaffected by other coexisting ions. After that, Job’s curve method, nuclear magnetic titration analysis, and mass spectrometry were used to study the binding mechanism of probe L and Zn2+. The results showed that probe L coordinated with Zn2+ is 1:1. The linear equations of different concentrations of Zn2+ and fluorescence intensity were obtained by fitting, and the detection limit of probe L for Zn2+ was determined to be 6.75 × 10-9 mol/L. The experimental study of standard addition and recovery showed that probe L could be used for the quantitative detection of Zn2+ in natural water samples. After that, we prepared L-doped sodium alginate hydrogel (SAL). The research results show that SAL has obvious adsorption capacity for Zn2+ in solution, and the color change before and after adsorption can be easily distinguished by the naked eye under ultraviolet light. SEM-EDS study showed that the microscopic morphology and composition of SAL changed significantly before and after adsorption. This fluorescent probe can be used for detection and removal of Zn2+ in aqueous solution. Also, probe L is effective for sensing for zinc (II) in living tumor cells. Overall, this work allows us to obtain a great potential to be applied to detect and remove Zn2+.

PEGylated near-infrared fluorescence probe for mitochondria-targetable hydrogen peroxide detection

Oxidative stress plays significant roles in the development of various diseases. H2O2 acts as a signaling molecule physiologically or harmful substance pathologically and the mitochondria are one of the most active places for the generation of H2O2. Thus, a new mitochondria-targeted probe 1 for H2O2 detection was synthesized herein, based on D-π-A structure with a large Stokes shift (150 nm) due to its ICT process. To improve its water solubility and sensitivity, probe 2 with PEG chain and probe 3 with two responsive boronated groups were then designed based on the structure of probe 1. As a result, the fluorescence intensity of probe 2 was far higher than that of probe 1 and probe 3 not only in vitro experiment but in cell imaging study with a larger linear range and signal-to-noise ratio, rendering it the best probe for further exogenous and endogenous H2O2 detection in Hela cells.

Fluorescent probe visualization for selective detection of cuprous ion.

Cuprous ion is an essential element for human life activities. However, excessive cuprous can cause dysfunction of the human body system. To help explain this evolving biology, we report a fluorescent probe for detecting unstable Cu(I). Cu(I) undergoes a metal complexation reaction with the sulfur element in the probe, resulting in a photoelectron transfer (PET) effect. The probe fluorescence is greatly suppressed, and rapid and selective visual detection of Cu(I) in the inorganic environment is realized. There is also a good linear relationship between the probe fluorescence intensity and the Cu(I) concentration (R2 = 0.992), which can realize the quantitative detection of Cu(I). When the probe concentration is 0.1μM, the detection limit is 15nM, and the detection limit of the visual method is as low as 0.1μM. This work provides a valuable starting point for real-time monitoring of the Cu(I) concentration in a human anaerobic environment based on active probes.