Fluorescent Probe For Sensitive Detection Research Articles

Boronic acid-functionalized tungsten disulfide quantum dots as a fluorescence probe for sensitive detection of dopamine

A fluorescence probe comprising boronic acid-functionalized tungsten disulfide quantum dots for the label-free detection of dopamine was developed. The detection method is based on the selective interaction between diols and aminophenylboronic acid. This interaction generates quenching of fluorescence due to aggregation and the inner filter effect of the fabricated fluorescence probe. The proposed method allows the determination of dopamine in the concentration range from 0.05 μM to 100 μM including a correlation coefficient of 0.9925 along with a low detection limit of 0.01 μM. It manifests a better selectivity towards dopamine in the existence of different interfering analytes. Furthermore, the applicability of the proposed method has been utilized in the real sample which showed promising results for diagnostic purposes.

A New Phenylazo-Based Fluorescent Probe for Sensitive Detection of Hypochlorous Acid in Aqueous Solution.

In this paper, we designed and synthesized a novel phenylazo-based fluorescent probe (RHN) for the sensing and imaging of hypochlorous acid (HClO) in mitochondria in living cells. In this process, HClO promoted the oxidation of the phenylazo group to generate a free Rhodol fluorophore moiety, which in turn restored strong fluorescence and realized the detection of HClO. As expected, RHN exhibited high selectivity, high sensitivity and rapid response, with detection limits as low as 22 nM (1.155 ng/mL). Importantly, the results of the cell imaging experiments indicated that RHN has the ability to image and sense HClO in mitochondria, which is of great significance for exploration of the specific role of HClO in both the immune system and diseases.

Deep-Red Emissive Fluorescent Probe for Sensitive Detection of Cysteine in Milk and Living Cells

Deep-Red Emissive Fluorescent Probe for Sensitive Detection of Cysteine in Milk and Living Cells

Synthesis, Structure and Fluorescent Probes for Sensitive Detection for Nitrobenzene of a Cd-MOF

Synthesis, Structure and Fluorescent Probes for Sensitive Detection for Nitrobenzene of a Cd-MOF

Ultrabright silicon nanoparticle fluorescence probe for sensitive detection of cholesterol in human serum.

A highly sensitive fluorescence-based assay for cholesterol detection was developed using water-dispersible green-emitting silicon nanoparticles (SiNPs) as a fluorescence indicator and enzyme-catalyzed oxidation product PPDox (Bandrowski's base) as a quencher. The SiNPs were facilely synthesized via a simple, one-step hydrothermal treatment using 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (AEEA) as the silicon source, which has ultrahigh quantum yield and low phototoxicity. Under the catalysis of cholesterol oxidase (ChOx), hydrogen peroxide (H2O2) was generated as a result of cholesterol oxidation. Utilizing p-phenylenediamine (PPD) as the substrate for horseradish peroxidase (HRP) in the presence of H2O2 led to the production of PPDox. Based upon the inner filter effect (IFE), the established ultrasensitive fluorescent assay could accurately measure cholesterol. The limit of detection (LOD) of the assay was 0.018μM with a linear range of 0.025-10μM. The results for the detection of real serum samples by the proposed assay were comparable to those by a commercial reagent kit, demonstrating that our proposed strategy has high application potential in disease diagnosis and other related biological studies.

A phthalimide-based ESIPT fluorescent probe for sensitive detection of Cu2+ in complete aqueous solution.

A novel fluorescence-enhanced probe 2-butyl-1,3-dioxoisoindolin-4-yl picolinate (BDIP) has been developed for the detection of Cu2+ based on the excited-state intramolecular proton transfer (ESIPT) process. BDIP utilized a phthalimide derivative as the fluorophore and selected picolinate ester as the recognition site for Cu2+. The probe displayed high selectivity, strong anti-interference ability, and a significant fluorescence enhancement effect for Cu2+ in phosphate buffer saline (PBS, 10mM, pH 7.4) with the detection limit of 31nM. BDIP also possesses the advantages of simple synthesis steps, large Stokes shift, and good water solubility. Moreover, BDIP was used for Cu2+ detection in real water samples, with the result being satisfactory.

Development of a Highly Specific, Selective, and Sensitive Fluorescent Probe for Detection of Mycobacteria in Human Tissues.

Tuberculosis (TB), including extrapulmonary TB, is responsible for more than one million deaths in a year worldwide. Existing methods of mycobacteria detection have poor sensitivity, selectivity, and specificity, especially in human tissues. Herein, the synthesis of a cholic acid-derived fluorescent probe (P4) that can specifically stain the mycobacterium species is presented. It is shown that P4 probe specifically binds with mycobacterial lipids, trehalose monomycolate, and phosphatidylinositol mannoside 6. P4 probe can detect mycobacteria in polymicrobial planktonic cultures and biofilms with high specificity, selectivity, and sensitivity. Moreover, it can detect a single mycobacterium in the presence of 10000 other bacilli. Unlike the probes that depend on active mycobacterial enzymes, the membrane-specific P4 probe can detect mycobacteria even in formalin-fixed paraffin-embedded mice and human tissue sections. Therefore, the ability of the P4 probe to detect mycobacteria in different biological milieu makes it a potential candidate for diagnostic and prognostic applications in clinical settings.

A Tritopic Terpyridine-Based Fluorescent Probe for Sensitive Detection and Analysis of Th4+, Zn2+ and F- Ions

A Tritopic Terpyridine-Based Fluorescent Probe for Sensitive Detection and Analysis of Th4+, Zn2+ and F- Ions

PVP–gold–copper nanocluster based NIR fluorescence probe for sensitive detection of malachite green

A novel NIR fluorescent probe based on PVP–Au/CuNCs has been developed, exhibiting good selectivity and stability for detecting malachite green (MG).

A Tritopic Terpyridine-Based Fluorescent Probe for Sensitive Detection and Analysis of Th4+, Zn2+ and F- Ions

A Tritopic Terpyridine-Based Fluorescent Probe for Sensitive Detection and Analysis of Th4+, Zn2+ and F- Ions

Green Synthesized Carbon Quantum Dots as Fluorescent Probes for Sensitive Detection of Metal Ions

Green Synthesized Carbon Quantum Dots as Fluorescent Probes for Sensitive Detection of Metal Ions

A fluorescent sensor-based tripodal-Bodipy for Cu (II) ions: bio-imaging on cells.

A general synthetic method was improved to synthesize a chemosensor based on a tripodal Bodipy (t-BODIPY) structure. The product and its intermediate products were successfully prepared and fully characterized. The metal ion sensing performance of the tripodal compound was evaluated by UV/Vis and fluorescence spectroscopies. According to the obtained data, t-BODIPY is a selective and sensitive fluorescence probe for detection of Cu2+ ions in the presence and in the absence of competing ions. This chemosensor presents relatively a low detection limit of 5.4×10-7 M for Cu2+. Bio-imaging studies on living yeast cells suggest that t-BODIPY has some advantages over other chemosensors to recognize copper (II) ions.

Controllable release ratiometric fluorescent sensor for hyaluronidase via the combination of Cu2+-Fe-N-C nanozymes and degradable intelligent hydrogel

As a popular controllable-released carrier, intelligent hydrogels are often used in drug delivery and disease therapeutics. Meanwhile, benefit from the mimic-enzyme activity performance, Fe–N–C nanozymes have been widely used in sensing and analysis. However, the combination of intelligent hydrogels with specific degradability and Fe–N–C nanozymes with enhanced activity in one system to achieve controllable and sensitive detection is rare. Herein, we combine intelligent hydrogel with mimic peroxidase activity enhanced Fe–N–C nanozymes to construct a ratiometric fluorescence probe for sensitive detection of hyaluronidase (HAase). The modification of copper ions has been proved to enhance the mimic enzyme activity of Fe–N–C nanozymes greatly. Cu2+ modified Fe–N–C nanozymes were embedded in hyaluronic acid hydrogel. In the presence of HAase, the HA hydrogel structure was hydrolyzed and released Cu2+-Fe-N-C nanozymes gradually. The released Cu2+-Fe-N-C nanozymes are used to catalyze the hydrogen peroxide system so that o-phenylenediamine is oxidized to orange fluorescent 2, 3-diaminophenolazine (DAP). Due to the electrostatic interaction, the fluorescence resonance energy transfer can occur between the negatively charged copper nanoclusters emitted by 430 nm and the positively charged DAP emitted by 560 nm. The activity of HAase was monitored according to the ratio of fluorescence intensity at 560 nm and 430 nm (F560/F430). The linear range of this method is 0–10.0 U/ml and the detection limit is 0.43 U/mL (S/N = 3). This strategy has been further applied to biological samples successfully.

A novel sensitive NMOF fluorescent probe for two photon imaging of glutathione in chemo-resistant cancer cells

Nanoscale metal-organic frameworks (NMOFs) with fluorescence properties have been proved to be a kind of excellent single photon fluorescence probes for sensitive detection and imaging of bioactive molecules in recent years. However, this kind of NMOFs fluorescent probe still exists some problems to be solved such as biological autofluorescence interference and poor tissue penetration. Compared with single photon fluorescence probes, two-photon fluorescence probes have attracted more and more attention in biomedical research recently due to the intrinsic advantages originated from simultaneous absorption of two low energy photons, such as lower excitation energy, less photodamage, deeper tissue penetration, smaller interference of spontaneous fluorescence and higher imaging resolution. Here, simply based on host-guest interactions, we for the first time developed a novel sensitive two-photon NMOF fluorescence probe for monitoring the fluctuation of endogenous glutathione (GSH) level in living cells, which plays an important role in cellular redox homeostasis. The detection limit of this sensitive probe is as low as 87 nM. After being successfully devoted to monitor the fluctuation of endogenous glutathione levels in different types of living cell lines, the probe was also successfully employed to evaluate the relationship between chemotherapeutic drug doxorubicin (DOX) resistance and GSH levels in Hela, HepG2 and normal L02 cells.

Biocompatible sulfur nitrogen co-doped carbon quantum dots for highly sensitive and selective detection of dopamine

In this work, sulfur and nitrogen co-doped carbon quantum dots (S,N-CQDs) were prepared via one-pot hydrothermal treatment of EDTA disodium and sodium sulfide. The prepared S,N-CQDs were characterized by TEM, XRD, FT-IR, XPS, UV–vis absorption and fluorescence spectra to characterize their morphology, crystal structure, functional groups, elemental composition, and optical properties. It was found that S and N elements were successfully doped into the CQDs and the morphology was approximately spherical with an average particle size of 2.16 nm, in which the excitation/emission wavelengths were 350 and 420 nm, respectively. Compared with single element doped CQDs, double element doped CQDs have a higher quantum yield and excellent optical stability. Cell experiments showed that S,N-CQDs had good biocompatibility because they had no obvious toxicity on both normal cell lines and cancer cell lines. More importantly, based on the synergy of static quenching and dynamic quenching, the S,N-CQDs were used as effective fluorescent probes for sensitive detection of DA, with high anti-interference and low limit of detection. Based on the good biocompatibility of S,N-CQDs, the detection of dopamine in actual serum samples were carried out and the results showed an excellent recovery rate. Therefore, this work provides a dopamine sensor with a practical application prospect.

Development of a one-step synthesized red emission fluorescent probe for sensitive detection of viscosity in vitro and in vivo

Diseases caused by metabolic abnormalities, such as inflammation and fatty liver, which are characterized by high viscosity, so it is necessary to detect the change of viscosity in vivo and in vitro. Due to the advantages of high sensitivity, noninvasive detection, high selectivity and real-time imaging, fluorescence imaging has become an effective means to detect biological parameters of biomolecules and life systems. Therefore, we have prepared a red emitting fluorescent probe NBI-V with easy synthesis which can ensure that the probe can be developed for the widely used to detection of viscosity changes in vivo and in vitro. The probe NBI-V has good stability, high response times, selectivity, and good biocompatibility. As the viscosity of a water-glycerol system increased from 1.29 cp to 937.48 cp, the fluorescence of NBI-V was increased by about 77 times. Biological experiments showed that the probe NBI-V can target mitochondria, and the Pearson correlation coefficient was as high as 0.89. What's more, it can distinguish normal liver from fatty liver, and can detect the viscosity changes caused by inflammation in mice.

A simple “turn off-on” ratio fluorescent probe for sensitive detection of dopamine and lysine/arginine

Herein, a novel and unique “off-on” single-excited dual-emissive ratio fluorescence sensor for highly selective and sensitive detection of dopamine and lysine/arginine has been developed via covalently connecting the yellowish-green fluorescent carbon dots (CDs) with the orange-red fluorescent AgInSe2@ZnS quantum dots (AISe QDs). This ratiometric fluorescence sensor provided with two-emission peaks at 495 and 575 nm under a single-excitation wavelength of 395 nm. The fluorescence of AISe QDs (F575) is effective quenched by dopamine and only efficientlyrecovered by lysine/arginine; meanwhile, the light of CDs (F495) remains unchanged. The fluorescence intensity ratio (F495/F575) showed a linear relationship with the concentration of DA in the range of 0–100 μM, and the detection limit as low as 0.21 nM. lysine and arginine with the detection limit of 0.36 nM and 26 μM, respectively. Furthermore, the fluorescence probe is successfully used to detect DA in human serum. Therefore, the as-synthesized probe shows excellent potential application for the determination of DA in real samples.

Highly Sensitive Fluorescent Probe for Detection of Paraquat Based on Nanocrystals.

Paraquat is one of the most toxic materials widely applied in agriculture in most countries. In the present study, a simple, innovative and inexpensive nano biosensor which is based on a thioglycolic acid (TGA) - CdTe@CdS core-shell nanocrystals (NCs) to detect paraquat, is suggested. The NCs based biosensor shows a linear working range of 10-100nM, and limited detection of 3.5nM. The proposed sensor that has been well used for the detection and determination of paraquat in natural water samples is collected from corn field and a canal located near to the corn field yielding recoveries as high as 98%. According to our findings, the developed biosensor shows reproducibility and high sensitivity to determine paraquat in natural water samples in which the amount of paraquat has low levels. The suggested method is efficiently applied to paraquat determination in the samples of natural water that are collected from a tap water and a canal located near to the cornfield.

Sulfhydryl functionalized carbon quantum dots as a turn-off fluorescent probe for sensitive detection of Hg2.

Mercury ion (Hg2+) is one of the most toxic heavy metal ions and lowering the detection limit of Hg2+ is always a challenge in analytical chemistry and environmental analysis. In this work, sulfhydryl functionalized carbon quantum dots (HS-CQDs) were synthesized through a one-pot hydrothermal method. The obtained HS-CQDs were able to detect mercury ions Hg2+ rapidly and sensitively through fluorescence quenching, which may be ascribed to the formation of nonfluorescent ground-state complexes and electron transfer reaction between HS-CQDs and Hg2+. A modification of the HS-CQD surface by –SH was confirmed using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The HS-CQDs sensing system obtained a good linear relationship over a Hg2+ concentration ranging from 0.45 μM to 2.1 μM with a detection limit of 12 nM. Delightfully, the sensor has been successfully used to detect Hg2+ in real samples with satisfactory results. This means that the sensor has the potential to be used for testing actual samples.

Facile synthesis of B,N-doped CQDs as versatile fluorescence probes for sensitive detection of cobalt ions in environmental water and biological samples

Fabrication of carbon quantum dots (CQDs) as versatile fluorescence probes for simultaneous detection of cobalt ion (Co2+) in various samples is still unmet. Herein, novel boron, nitrogen-doped carbon quantum dots (B,N-CQDs) were facile synthesized via one-step hydrothermal method, in which 3-carboxyphenylboronic acid and ethylenediamine were selected as precursors. Owing to the unique properties of the precursors, the obtained B,N-CQDs exhibited excellent recognition capability of Co2+, favorable biocompatibility, and high fluorescence quantum yield (FLQY, 64.8%), which enabled the B,N-CQDs as versatile fluorescence probes for sensitive detection of Co2+. The response of the probes to Co2+ was linear in two ranges of 0.5–10 and 10–2000 nM with limit of detection (LOD) of 0.52 nM. Feasibility of practical application of the probes was assessed by quantitative detection of trace Co2+ in real water samples including sewage water, river water and tap water. Furthermore, Co2+ in human urine was detected by using the probes with recoveries between 96% and 104%, indicating that the established probes could meet the requirements of practical detection in urine samples. Besides, the probes were successfully applied to monitoring Co2+ in A549 cells via fluorescence imaging attributed to their excellent photostability and high signal-to-background ratio. All these results show that the designed B,N-CQDs are ideal probes for simultaneously detecting Co2+ in environmental water and biological samples, which would expand the practical application of CQDs.