Fluorescent Probe For Selective Detection Research Articles

A novel benzo[a]phenazin-based fluorescence probe for selective detection of cysteine with anti-cancer potency

Among the physiological and pathological sulfur-containing species, cysteine (Cys) is the most typical one which is an important component of the REDOX system in vivo. Monitoring the level of Cys from other competing species seems quite important in pre-clinical diagnosis and therapeutic evaluation. Herein, we developed a selective fluorescent probe, BPCys, for Cys from the benzo[a]phenazin backbone which had the potential of anti-cancer potency. BPCys suggested advantages including high specificity (40 fold over other species), high sensitivity (detection limit: 18 nM), wide pH adaptability (6.0–11.0) and in particular, the anti-cancer effect. Biological assays and in silico simulation hinted the potency of the detecting product on Topoisomerase I/II. In brief, this study raised a practical strategy for monitoring the Cys level in living cells, especially in cancer models with its anti-cancer potential, thus opened the mind of exploring more specific tool for specific applications.

Nile-Red-Based Fluorescence Probe for Selective Detection of Biothiols, Computational Study, and Application in Cell Imaging.

A new colorimetric and fluorescence probe NRSH based on Nile-red chromophore for the detection of biothiols has been developed, exhibiting high selectivity towards biothiols over other interfering species. NRSH shows a blue shift in absorption peak upon reacting with biothiols, from 587 nm to 567 nm, which induces an obvious color change from blue to pink and exhibits a 35-fold fluorescence enhancement at 645 nm in red emission range. NRSH displays rapid (<1 min) response for H2S, which is faster than other biothiols (>5 min). The detection limits of probe NRSH towards biothiols are very low (22.05 nM for H2S, 34.04 nM for Cys, 107.28 nM for GSH and 113.65 nM for Hcy). Furthermore, NRSH is low cytotoxic and can be successfully applied as a bioimaging tool for real-time monitoring biothiols in HeLa cells. In addition, fluorescence mechanism of probe NRSH is further understood by theoretical calculations.

A quinoline-based chromogenic and ratiometric fluorescent probe for selective detection of Mg2+ ion: Design, synthesis and its application in salt lake brines and bioimaging

A fluorescent probe was rational designed and prepared to distinguish Mg2+ ion from Ca2+ ion, in which 8-hydroxyquinoline acted as not only a fluorophore but also a recognition group. Notably, this probe QB (8-hydroxyquinoline-5-benzothiazole) shows two fluorescence response modes for highly selective detection of Mg2+ ion, namely fluorescence ratiometric mode and turn-on mode, which can be realized by controlling the excitation wavelength at 356 nm or 425 nm. After the addition of Mg2+ ion, the color of the QB solution changed from colorless to yellow, which can be easily found by naked eye. All experimental results suggested that probe QB has a high selectivity toward Mg2+ ion in the presence of other cations. Its detection limit for Mg2+ ion was estimated as low as 0.142 μM, and this value was far lower than the intracellular concentration (0.5–1.2 mM). The detection mechanism was proposed further by the experiment of 1H NMR titration and theoretical calculation. More significantly, this probe was successfully used to detect Mg2+ ion in brine samples as a quantitative method, and was also applied to detecting and imaging Mg2+ ion in living cells, indicating its great application value in practical use for the detection of Mg2+ ion.

Ascorbic acid stabilized copper nanoclusters as fluorescent probes for selective detection of tetracycline

In this work, we synthesized the copper nanoclusters (AA-Cu NCs) by protection and chemical reduction of ascorbic acid. The characterization results illustrated that the water-soluble nanoclusters were stable and well monodispersed with strong fluorescence intensity. The fluorescence of the nanoclusters could be selectively and efficiently quenched by tetracycline. There were two excellent linear relationships between the F0/F values and tetracycline concentrations in the range of 0.9–70 μM and 80–150 μM. The quenching mechanism might be static quenching and inner filter effect (IFE). More importantly, the fluorescent probe AA-Cu NCs could efficiently detect tetracycline in environmental water.

A novel ratiometric fluorescent probe for selective detection and imaging of H2S.

In this work, a novel phenoxazine-based fluorescent probe BPO-N3 was developed to detect H2S. The results showed that the probe had high selectivity and sensitivity toward H2S, and its detection mechanism was based the ratio between green and red fluorescence signals; its detection limit was as low as 30nM. The fluorescent imaging experiments further showed that the probe BPO-N3 could successfully detect endogenous and exogenous H2S in living cells. This probe can be used as a powerful tool for in-depth study of H2S function in various physiological processes.

Cyanide Sensing in Water Using a Copper Metallogel through "Turn-on" Fluorescence.

The development of fluorescent probes for selective detection of cyanide has gained considerable attention over the past two decades due to benefits like high selectivity as well as sensitivity, fast response, visual output, accurate quantification, and a simplified sample preparation procedure. However, the propensity of supramolecular gels toward fluorescence sensing of cyanide in aqueous medium is not well explored until now. Herein, we report the design and synthesis of a novel copper based metallogel capable of sensing cyanide in water by fluorescence "turn on". Toward this, a terpyridine attached poly(aryl ether) dendrone derivative (G1) is synthesized which forms gel and exhibits Aggregation Induced Emission (AIE). The addition and diffusion of copper ions to the gel resulted in the formation of a nonluminescent copper metallogel (CuG). The copper metallogel could selectively sense cyanide in water by a fluorescence "turn-on" signal due to the regeneration of the AIE active gel. The mechanistic pathways of the sensing have been studied, and the detection limit for sensing was found to be as low as 1.09 μM. A thin film of CuG was prepared by casting the gel and used as a test strip for the visual detection of cyanide in water.

Coumarin-Based Dual Chemosensor for Colorimetric and Fluorescent Detection of Cu2+ in Water Media.

A novel coumarin derivative (5) was synthesized and used as a colorimetric and fluorescent probe for selective detection of Cu2+ ions in the presence of other metal ions, with the detection limits of 5.7 and 4.0 ppb, respectively. Cu2+ ion reacts with probe 5 to form a 1:1 stoichiometry complex, resulting in a remarkable redshift of absorption maximum from 460 to 510 nm, as well as almost completely quenching fluorescence intensity of probe 5 at the wavelength of 536 nm. These changes can be distinctly observed by naked eyes. In addition, the working pH range of probe 5 is wide and suitable for physiological conditions, thus probe 5 may be used for detection of Cu2+ ions in living cells. The stable structures of probe 5 and its 1:1 complex with Cu2+ ion were optimized at the PBE0/6-31+G(d) level of theory. The presence and characteristics of bonds in compounds were studied through atoms in a molecule and natural bond orbital analysis. The formation of the complex led to a strong transfer of electron density from probe 5 as a ligand to Cu2+ ion, resulting in breaking the π-electron conjugated system, which is the cause of fluorescence quenching and color change of 5-Cu2+ complex.

Fluorescent detection of Al(III) and CN− in solid and aqueous phases and their recognition in biological samples

A new simple Schiff base based chemoreceptor (R) has been designed, synthesized and characterized using 1H and 13C NMR, mass and single crystal XRD techniques. R acts as an efficient fluorescent probe for selective detection of Al(III) and cyanide ions in methanol: water (20:80, v/v) medium thorough different emissions. The mode of coordination of R with Al(III) has been recognized by 27Al and 1H NMR and FT-IR studies and the results suggest an octahedral complex formation between them. The detection of cyanide occurs via the deprotonation of phenolic –OH group followed by nucleophilic addition of cyanide to imine C-atom which has been confirmed from 1H and 13C NMR titration experiments. R reacts with Al(III) and cyanide in a 1:1 stoichiometric manner with detection limits of 1.8 and 0.76 μM, respectively. The receptor shows an excellent ability for the detection these ions in a wide pH range. Most interestingly, R could detect these ions also in solid phase via similar mechanisms which are delineated using solid state reflectance, fluorescence and FT-IR spectral techniques and TD-DFT calculations. The probe has also been successfully applied for the bio-imaging of Al(III) in living cells and detection of endogenous biological cyanide in food samples.

Coumarin-Based Reversible Fluorescent Probe for Selective Detection of Cu2+ in Living Cells.

Copper ion plays an important role in many biological processes in human body. H2S is considered as the third gasses transmitter after carbon monoxide and nitric oxide. Here a novel ICT-based fluorescent ON-OFF-ON probe for Cu2+ and H2S detection was developed. Selectivity and sensitivity of probe was confirmed in aqueous Tris-HCl buffer (10mM, pH7.4, containing 90% acetonitrile). Probe DF-CU shows high selectivity over other analytes. The degree of fluorescence quenching is linearly associated with the concentration of Cu2+ (R2= 0.9919). The limit of detection (LOD, calculated according to the 3σ/slope) for Cu2+ was 6.4μM. Probe can work in almost all pH. The probe shows a very fast response to Cu2+ (within 10s). Its response to copper ion could be reversed by H2S. The complex of probe with Cu2+ could be used for H2S detection. Furthermore, this ON-OFF-ON fluorescent probe successfully applied in the living cells for the detection of Cu2+ and H2S.

A water-soluble fluorescent probe for selective detection of 2,4,6-trinitrophenol (TNP) in real samples

In this study, we presented a water-soluble fluorescent probe (HBN) for 2,4,6-trinitrophenol (TNP) detection by introducing a quaternary ammonium group. Probe HBN exhibited significant fluorescence quenching toward 2,4,6-trinitrophenol via electrostatic and charge transfer interactions. The obtained results demonstrated that probe HBN could rapidly (<30 s) and selectively detect 2,4,6-trinitrophenol over other nitroaromatic compounds and relevant ions with a low detection limit of 57 nM. The excellent sensing properties of probe HBN enable its applications in visual detection of 2,4,6-trinitrophenol by a paper test system and monitoring 2,4,6-trinitrophenol in environmental water systems.

A novel coumarin‐based fluorescent probe for selective detection of cysteine over homocysteine

AbstractA coumarin‐based fluorescent probe containing both acrylate moiety and an allyl substituent was developed for distinguishing cysteine from homocysteine. The maximum absorption wavelength of the probe showed a bathochromic shift upon addition of cysteine and the colour changed from colourless to yellow. The maximum fluorescence emission at 462 nm of the probe was dramatically enhanced upon addition of cysteine in aqueous solution. In HEPES buffer (pH = 7.4, EtOH/H2O = 9:1, v/v), both of the fluorescence emission bands of the probe at ca. 390 and 462 nm were intensely enhanced upon the addition of cysteine, while other amino acids, namely, homocysteine, asparaginic acid, methionine, glycine, phenylalaninase, valine, tryptophan, serine, glutamic acid and glutathione, did not cause a remarkable change. The probe can be used for selectively colorimetric and ratiometric fluorescent detection of cysteine over homocysteine and other common amino acids in both organic media and aqueous solution. The concentration of cysteine can be estimated by titration of the probe in aqueous solution, and the detection limit of the probe towards cysteine was 2 μmol/L.

A near-infrared fluorescent probe for selective detection of fluorion

Abstract In this work, we have designed and synthesized the fluorescent probe 1, which was capable to selectively detect fluoride anion (F−). More importantly, the probe 1 possessed near-infrared excitation and emission wavelengths (excitation at 650 nm and emission at 695), and the probe solution had changed dramatically from yellow to cyan with the addition of F–. In addition, the fluorescence intensity exhibited perfectly positive correlation with concentration of F− concentration from 0 to 40 μM (R2 = 0.9972), which offered the important condition for quantitative analysis. The probe 1 owned detection limit of 46 nM. Therefore, this near-infrared probe can be of great benefit for detecting F− in practical application.

A “Turn‐On” Fluorescence Probe for Selective Detection of Al 3+ in Aqueous Environment: Crystal Structure, Theoretical and Cell Imaging Studies

A “Turn‐On” Fluorescence Probe for Selective Detection of Al ³⁺ in Aqueous Environment: Crystal Structure, Theoretical and Cell Imaging Studies

A New Fluorescent Probe for Selective Detection of Endogenous Cysteine and Live Cell Imaging

AbstractThe detection of biothiols has attracted extensive interest owing to their vital importance in maintaining bioprocesses. Here, we reported a fluorescent probe MANK with facile preparation and excellent water solubility, which can effectively distinguish Cys from its two analogues glutathione (GSH) and homocysteine (Hcy) with a large “turn‐on” fluorescent signal of more than 40‐fold enhancement. Importantly, during the selective detection of Cys, the large concentration differences of three biothiols in living cells had been taken into account. The maleyl group in MANK acted both as a recognition site and fluorescence quenching group. And in the presence of Cys, the thiol group of Cys reacted with maleyl group of MANK by nucleophilic addition and the resulting adduct restored fluorescence emission with a high fluorescent quantum yield of 0.40 in phosphate buffered saline (PBS). Finally, it was successfully utilized to map the endogenous Cys in living cells by confocal microscopy.

Fabrication of a water-soluble near-infrared fluorescent probe for selective detection and imaging of dipeptidyl peptidase IV in biological systems.

Dipeptidyl peptidase IV (DPP-IV) is a transmembrane glycoprotein known to regulate T cell activation, which is related to various pathological processes and has become a potential target to treat type 2 diabetes mellitus. Therefore, it is significant for the evaluation of endogenous DPP-IV activity in various biological systems. Herein, a water-soluble near-infrared (NIR) fluorescent probe HCA-D based on cyanine dyes as the fluorophore and glycyl-prolyl peptide as the specific recognition sequence was developed for the assay of dipeptidyl peptidase IV (DPP-IV) activity. Upon addition of DPP-IV, HCA-D can emit a significant turn-on NIR fluorescence signal under physiological conditions and exhibit high selectivity toward DPP-IV. This feature was available for quantifying DPP-IV in the range from 0.62 to 10 ng mL-1 with a detection limit of 0.19 ng mL-1. Furthermore, the present probe was successfully employed for monitoring DPP-IV in serum samples from diabetic and healthy people, and imaging of DPP-IV in living cells and tumor mice models. These results demonstrate that the designed probe provides a promising tool to explore the relationship between DPP-IV and diabetes mellitus or other diseases. Perhaps, it may become a prospective image-guided tumor resection indicator based on the abnormal expression of DPP-IV activity in the future.

Deep imaging for visualizing nitric oxide in lipid droplets: discovering the relationship between nitric oxide and resistance to cancer chemotherapy drugs.

A near-infrared two-photon fluorescent probe (TAN) was synthesized for selective detection and deep-depth imaging of NO in lipid droplets. All results demonstrated that NO production in lipid droplets is closely correlated with the resistance to anti-tumor drugs, and NO inhibitors can effectively improve the efficacy of chemotherapeutic agents.

Synthesis of green-emitting carbon quantum dots with double carbon sources and their application as a fluorescent probe for selective detection of Cu2+ ions.

Green-emitting carbon quantum dots (G-CQDs) were prepared using tartaric acid and bran by one-pot solvothermal treatment and had photoluminescence quantum yields (PL QY) as high as 46%. The morphology of the G-CQDs is characterized by TEM, which shows the average diameter of G-CQDs is approximately ∼4.85 nm. The FT-IR spectra display the presence of –OH, C–N, N–H and –COOH on the surface of the G-CQDs. The emission wavelength of the G-CQDs was ∼539 nm in the case of ∼450 nm excitation wavelength, which corresponds to the green fluorescence. Furthermore, the G-CQDs were used as a fluorescent probe for detection Cu2+ ions, and demonstrated a linear distribution between ln(F/F0) and the Cu2+ ions concentration. Specifically, the Cu2+ ion concentration should fall in the G-CQD concentration range of 0–0.5 mM and the detection limit is 0.0507 μM. Thus, due to the excellent chemical stability and good luminescence performance, these G-CQDs could be excellent probes widely used in detection fields.

A quinoline-based fluorescent probe for selective detection and real-time monitoring of copper ions - a differential colorimetric approach.

A quinoline moiety was used as a building block for designing a probe for the selective detection of copper ions in a partially aqueous medium. We have developed a molecular sensing system which gives insight into the complex physiological and redox aspects of labile copper. The probe provides a colorimetric approach for distinguishing cuprous and cupric ions along with their simultaneous discrimination from other metal ions in the visible range of the spectrum. The chemosensor showed a remarkable fluorescence enhancement along with a significant bathochromic shift of about 35 nm. The detection limit of the probe was found to be 1.03 μM which is optimally favorable to be applied in real-time monitoring. Fabrication of paper strips with the probe was done to detect the presence of cuprous ions in the real sample. The value of the binding constant (1.37 × 104 M-1) suggests stable complex formation between the metal ion and the sensing probe. The photoluminescence and structural aspects of the chemosensor were characterized by using fluorescence, absorption, ESI-MS, and 1H NMR spectroscopy. Furthermore, the cytotoxic nature and bioimaging properties of the probe were interpreted in vitro on RAW 264.7 macrophage cell lines and peripheral blood mononuclear cells (PBMCs) respectively.

Carbon quantum dot-AgOH colloid fluorescent probe for selective detection of biothiols based on the inner filter effect

Here, we present a selective and sensitive fluorescent probe for the detection and distinction of biothiols, such as glutathione (GSH) and cysteine (Cys). The adsorbance of Cys onto the surface of AgOH colloid could result in enhanced absorbance from 250 to 400nm in the UV-vis absorption spectrum, while the addition of GSH could dissolve the AgOH colloid resulting in no change in the UV-vis absorption spectrum. Utilizing these different phenomena, two fluorescent probes were established based on the inner filter effect (IFE). The first probe, the "CDs-AgOH colloid" fluorescent probe, was used to quantitatively analyze Cys over a linear concentration range from 33 to 317μM and a detection limit of 7.2μM. The second probe, the "CDs-AgOH colloid-Cys" fluorescent probe, was used to quantitatively analyze GSH, with a detection limit down to 3.6μM, and a linear range of detection of approximately 16.7 to 100μM. The fluorescent probes were successfully applied for the detection of GSH in a fetal bovine serum (FBS) sample. Based on these results, IFE is considered to be an effective way to distinguish GSH and Cys.

AND-Logic Based Fluorescent Probe for Selective Detection of Lysosomal Bisulfite in Living Cells.

Sulfur dioxide (SO2) plays significant roles in regulating cell apotosis and inflammation. However, there are complex interactions between small biomolecules in cells, and the identification of these coexisting biomarkers remains a challenge. Herein, we report an AND logic gate based fluorescent probe (NY-Lyso), operating by responding to pH differences between organelles in cell and selectively reacting with bisulfite (HSO3-). This approach allows the fluorescence of the probe to remain silent under neutral or alkaline conditions, notably, is activated by costimulation of lower pH and bisulfite. Furthermore, it was confirmed to be biocompatible and could be employed to monitor HSO3- in lysosomes of living cells. The proposed method demonstrated more practical and outstanding capabilities in targeted and real-time monitoring, providing an effective optical tool for biomarker sensing.