Fluorescent Probe For Detection Research Articles

Coumarin-hemicyanine-based ratiometric fluorescent probes for detection of strong acidity

Fluorescent probes for determination of strongly acidic pH values are urgently needed, especially the ones with ratiometric signal changes. Here, two fluorescent probes (CP and CyC) based on coumarin-hemicyanine were synthesized. Both probes emitted red fluorescence under weakly acidic to weakly alkaline conditions, whereas blue fluorescence under strongly acidic conditions. Notably, probe CP displayed good stability, water solubility, anti-interference ability, repeated utilization and instant response. Encouraged by the good performance, probe CP based test strips were used to indicate the pH of aqueous solutions, and to detect HCl or NH3 vapor in air reversibly.

A new fluorescent probe for detection of hydrazine and extremely acidic pH in different modes

Toxic hydrazine poses a huge threat to living organisms and our environment. Extremely acidic pH is also harmful to various ecosystems. Here, a coumarin-based dye called CMM has been synthesized for the ratiometric detection of hydrazine (F504 nm/F560 nm). CMM could detect gaseous hydrazine in the environment and endogenous hydrazine in live cells. Furthermore, the fluorescence at 563 nm of CMM was stable from pH 10.0 to 2.0, whereas increased greatly from pH 2.0 to 1.2. Thus, the probe could also detect extremely acidic pH with great fluorescence enhancement. The pKa value was determined to be as low as 1.41. We anticipate that the probe could provide a good candidate for detection of toxic hydrazine and extremely acidic pH.

A sensitive analytical strategy of oligonucleotide functionalized fluorescent probes for detection of nusinersen sodium in human serum

Spinal muscular atrophy (SMA) is a rare autosomal recessive neuromuscular disease. Nusinersen sodium (NS) is the world's first antisense oligonucleotide (ASO) drug for SMA precise targeted therapy. However, the limited half-life of oligonucleotides and their tendency to accumulate in hepatic and renal tissues presented significant challenges for clinical investigation and therapeutic drug monitoring. In this study, we proposed an analytical strategy based on the specific capture of oligonucleotide functionalized fluorescent probes by single stranded binding proteins (SSB) for ultra-sensitive and high-throughput detection of nusinersen sodium in human serum. The magnetic nanoparticles modified with single-strand binding protein (MNPs-SSB) selectively bonded to the red fluorescent quantum dots functionalized with oligonucleotides (RQDs-ssDNA) that were complementary to nusinersen sodium. Upon interaction with nusinersen sodium, RQDs-ssDNA formed a double-stranded complex (RQDs-ssDNA-NS), resulting in enhanced red fluorescence after magnetic separation as it was no longer captured by MNPs-SSB but remained in the supernatant. A quantitative analysis of nusinersen sodium in biological samples was successfully achieved by establishing a relationship between fluorescence intensity and its concentration. The detection signal F/F0 exhibited a linear correlation (R2 = 0.9871) over a wide range from 0.1 nM to 200 nM, with a limit of detection (LOD) of 0.03 nM, demonstrating the high specificity and rapid analysis time (only 30 min). This method provided a novel approach for sensitive, high-throughput, and specific analysis of nusinersen sodium and similar ASO drugs.

Advancements in Small Molecule Fluorescent Probes for Superoxide Anion Detection: A Review.

Superoxide anion (O2•-), a significant reactive oxygen species (ROS) within biological systems, plays a widespread role in cellular function regulation and is closely linked to the onset and progression of numerous diseases. To unveil the pathological implications of O2•- in these diseases, the development of effective monitoring techniques within biological systems is imperative. Small molecule fluorescent probes have garnered considerable attention due to their advantages: simplicity in operation, heightened sensitivity, exceptional selectivity, and direct applicability in monitoring living cells, tissues, and animals. In the past few years, few reports have focused on small molecule fluorescence probes for the detection of O2•-. In this small review, we systematically summarize the design and application of O2•- responsive small molecule fluorescent probes. In addition, we present the limitations of the current detection of O2•- and suggest the construction of new fluorescent imaging probes to indicate O2•- in living cells and in vivo.

Near-infrared fluorescent probe for detection of hydrogen sulfide in water samples and food spoilage

Hydrogen sulfide (H2S) is a common toxic gas that threatens the quality and safety of environmental water and food. Herein, a new near-infrared fluorescent probe DTCM was synthesized and characterized by single crystal X-ray diffraction for sensing H2S. It exhibited a remarkable “turn-on” near-infrared (NIR) emission response at 665 nm with a remarkably massive Stokes shift of 175 nm, super-rapid detection ability (within 30 s), excellent photostability, high selectivity and sensitivity (limit of detection, LOD = 58 nM). Additionally, the probe was successfully utilized for the detection of H2S in environmental water samples. The DTCM-loaded test papers enabled convenient and real-time monitoring of H2S produced by food spoilage.

Development of a Coumarin-derived Fluorescent Probe for Detection of HOCl and its Application in Cells and Zebrafish.

We have prepared a simple, universal and efficient coumarin-derived fluorescent probe (XDS1) to detecting HOCl. The experimental findings revealed that the introduction of HOCl produced an obvious quenching effect on the probe with high selectivity and sensitivity. The calculated limit of detection (LOD) was as low as 0.02μM. Furthermore, an impressive response time of less than 10 s was observed when XDS1 detecting HOCl. Importantly, the probe XDS1 exhibited negligible cytotoxicity, thereby facilitating its application for imaging HOCl within biological environment. The probe XDS1 had been successfully used for specific detection in cells.

Fabrication of a ratiometric fluorescent probe based on Tb3+ doped dual-emitting carbon dots for the detection of cytochrome c

Cytochrome c (Cyt-c) was commonly an intrinsic biomarker for a variety of cellular characteristics, such as respiration, energy levels, and apoptosis. Herein, a simple fluorescence sensor was constructed for the detection of Cyt-c in buffer and real serum samples. The carbon dots doped with Tb3+ on the premise of 1-(2-pyridylazo)-2-naphthol (PAN) were fabricated and used as a dual-emission ratiometric fluorescent probe for detecting Cyt-c based on the internal filtering effect (IFE). As a fluorescent probe for ultra-sensitive detection, Cyt-c was quantitatively detected at different concentrations from 1 to 1000 nM. The fluorescent detection method for Cyt-c showed a good linear relationship from 1 to 50 nM, and the limit of detection (LOD) was 0.35 nM. In the recovery range of 101.27–103.39 % in human serum samples, the relative standard deviation (RSD) was less than 3.27 % (n = 3). In the end, the possible structures of CDs were predicted by DFT theoretical simulation calculations. All the results proved the ability of carbon dots as fluorescent probes to detect biomarkers and the application prospects in bioanalysis.

Room temperature, ultrafast and one-step synthesis of highly fluorescent sulfur quantum dots probe and their logic gate operation

The direct and rapid conversion of abundant and cheap elemental sulfur into fluorescent sulfur quantum dots (SQDs) at room temperature is a critical and urgent challenge. Conventional synthesis methods require high temperatures, high pressures, or specific atmospheric conditions, making them complex and impractical for real applications. Herein, we propose a simple method for synthesizing SQDs simply by adding H2O2 to an elemental sulfur-ethylenediamine (S-EDA) solution at room temperature. Remarkably, within a mere 10 min, SQDs with a photoluminescence quantum yield of 23.6 % can be obtained without the need for additional steps. A comprehensive analysis of the mechanism has demonstrated that H2O2 is capable of converting Sx2− ions generated in the S-EDA solution into zero-valent sulfur atoms through oxidation. The obtained SQDs can be utilized as a fluorescent probe for detection of tetracycline (TC) and Ca2+ ions with the limit of detection (LOD) of 0.137 μM and 0.386 μM respectively. Moreover, we have developed a sensitive logic gate sensor based on SQDs, harnessing the activated cascade effect to create an intelligent probe for monitoring trace levels of TC and Ca2+ ions. This paper not only presents a viable approach for ultrafast and scalable synthesis of SQDs at room temperature, but also contributes to the efficient utilization of elemental sulfur resources.

Aggregation-induced-emission red carbon dots for ratiometric sensing of norfloxacin and anti-counterfeiting

The detection of trace antibiotic residues holds significant importance because it’s related to food safety and human health. In this study, we developed a new high-yield red-emitting carbon dots (R-CDs) with aggregation-induced emission properties for ratiometric sensing of norfloxacin. R-CDs were prepared in 30 min using an economical and efficient microwave-assisted method with tartaric acid and o-phenylenediamine as precursors, achieving a high yield of 34.4 %. R-CDs showed concentration-dependent fluorescence and aggregation-induced-emission properties. A ratiometric fluorescent probe for detecting the norfloxacin was developed. In the range of 0–40 μM, the intensity ratio of two emission peaks (I445 nm/I395 nm) towards norfloxacin show good linear relationship with its concentrations and a low detection limit was obtained (36.78 nM). In addition, complex patterns were developed for anti-counterfeiting based on different emission phenomenon at different concentrations. In summary, this study designed a novel ratiometric fluorescent probe for detection of norfloxacin, which greatly shortens the detection time and improves efficiency compared with high-performance liquid chromatography and other methods. The study will promote the application of carbon dots in anti-counterfeiting and other related fields, laying the foundation for the preparation of low-cost photosensitive anti-counterfeiting materials.

Cover Picture: Metal‐Organic Frameworks as a Fluorescent Probe for Detection of Pathogenic Biomarkers in Human Urine (BKCS 4/2024) Seyeon Jeong, Hoi Ri Moon

The cover picture illustrates metal‐organic frameworks (MOFs) being used as fluorescent probes to detect biomarkers in human urine. MOF‐based fluorescent probes facilitate the diagnosis of diseases, including pheochromocytoma, toluene exposure, vitamin deficiencies, gout, hyperuricemia, cancers, various body disorders, and teratogenic effects, with low detection limits. Unlike conventional disease diagnosis methods such as biopsies or blood collection, detecting pathogenic biomarkers in human urine is non‐invasive and carries less risk. More details are available in the article by Seyeon Jeong and Hoi Ri Moon. image

An efficient lipid droplet-targeted fluorescent probe for detection of intracellular viscosity.

Lipid droplet, an intracellular lipid reservoir, is vital for energy metabolism and signal transmission in cells. The viscosity directly affects the metabolism of lipid droplets, and the abnormal viscosity is associated with the occurrence and development of various diseases. Therefore, it is indispensable to develop techniques that can detect viscosity changes in intracellular lipid droplets. Based on twisted intramolecular charge transfer (TICT) mechanism, a novel small-molecule lipid droplet-targeted viscosity fluorescence probe PPF-1 was designed. The probe was easy to synthesize, it had a large Stokes shift, stable optical properties, and low bio-toxicity. Compared to being in methanol solution, the fluorescence intensity of PPF-1 in glycerol solution was increased 26.7-fold, and PPF-1 showed excellent ability to target lipid droplets. Thus, the probe PPF-1 could provide an effective means of detecting viscosity changes of lipid droplets and was of great value for physiological diagnosis of related diseases, pathological analysis, and medical research.

Controllable functionalization of amino-functionalized graphene quantum dots as fluorescent probe for detection of Cu(Ⅱ) ions detection

Herein, the amino-functionalized graphene quantum dots (GQDs) can be applied for selective detection of Cu(Ⅱ) ions in solutions via photoluminescence (PL) measurement, the PL emission intensities of the GQDs gradually decreased with the increase of Cu2+ concentration (0–100 μm), the PL intensity (quenching effect) decreases almost linearly with increasing Cu2+ concentration. Its correlation coefficient R2 is 0.9529. Quenching of the PL emission by the presence of copper(Ⅱ) ions is attributed to the surface functional groups attached to the GQDs, which can interact with metal ions so that the electrons in the excited state of the GQDs are transferred into the unoccupied orbits of Cu(Ⅱ) ions. Corresponding physical mechanism is proposed to gain an understanding about how the presence of the Copper(Ⅱ) ions can affect the PL emission from GQDs.

A simple, rapid and sensitive sandwich immunoassay based on poly(N-isopropylacrylamide) for the detection of alpha-fetoprotein

Alpha-fetoprotein (AFP), as a tumor marker, plays a vital role in the diagnosis of liver cancer. In this work, a novel sandwich immunoassay based on a thermosensitive polymer, poly(N-isopropylacrylamide) (PNIPAM), was developed for the detection of AFP. This immunoassay could realize one-step rapid reaction within 1 h, and facilitate the separation of the target molecules by incorporating PNIPAM. In this method, a conjugate of PNIPAM and capture antibody (Ab1) was successfully synthesized as a capture probe and the synthetic method of PNIPAM-Ab1 was simple, while the detection antibody (Ab2) was labeled with fluorescein isothiocyanate (FITC) to form a fluorescent detection probe. By employing a sandwich immunoassay, the method achieved quantitative determination of AFP, exhibiting a wide linear range from 5 ng/mL to 200 ng/mL and a low detection limit of 2.44 ng/mL. Furthermore, it was successfully applied to the analysis of spiked human serum samples and the screening of patients with hepatic diseases in clinical samples, indicating its potential application prospect in the diagnosis of liver cancer.

Near-infrared dual-response fluorescent probe for detection of N2H4 and intracellular viscosity changes in biological samples and various water samples

N2H4 is a common raw material used in the production of pesticides and has good water solubility, so it may contaminate water sources and eventually enter living organisms, causing serious health problems. Viscosity is an important indicator of the cellular microenvironment and an early warning signal for many diseases. The high reactivity of hydrazine depletes glutathione (GSH) in hepatocytes, causing oxidative stress ultimately leading to significant changes in intracellular viscosity and even death. Therefore, it is particularly important to develop an effective method to detect N2H4 and viscosity in environmental and biological systems. On this basis, we developed two fluorescent probes, BDD and BHD, based on xanthene and 2-benzothiazole acetonitrile. The experimental results show that BHD and BDD have good imaging capabilities for N2H4 in cells, zebrafish and Arabidopsis. BHD and BDD also showed sensitive detection and fluorescence enhancement in the near-infrared region when the intracellular viscosity was changed. Notably, the probe BDD has also successfully imaged N2H4 in a variety of real water samples.

Rhodamine B- and coumarin-modified chitosan as fluorescent probe for detection of Fe3+ using quenching effect

Rhodamine B- and coumarin-modified chitosan as fluorescent probe for detection of Fe3+ using quenching effect

A hemicyanine-based fluorescent probe for detection of pH and its applications in live cells imaging and food monitoring

pH as an important parameter is closely related to many pathological processes and food freshness. In this paper, a new pH-sensitive fluorescent probe 1 based on hemicyanine dye was synthesized and used for the detection of pH in live cells and food spoilage. Under neutral and alkaline conditions, the phenolic hydroxyl group of the probe deprotonates, forming a closed spirocyclic structure and resulting in fluorescence quenching. Under acidic conditions, the probe maintains an open-loop structure and has intense fluorescence. The probe possessing good selectivity and stability can target lysosomes and visualize the exogenous pH in live cells. Furthermore, by using this probe, we successfully achieved the monitoring of pH in metamorphic process of shrimp and pork. This probe is expected to provide a good imaging tool for real-time detection of pH in live cells and food monitoring.

Reusable Cu‐Poly(4‐vinylpyridine‐co‐ethylbenzene) Complex as Catalyst for Chan‐Lam C−N Cross Coupling

AbstractA novel heterogeneous polymer supported catalyst Cu‐PVPEVB has been developed by complexation of CuI in the matrix of the polymer poly(4‐vinylpyridine‐co‐ethylvinylbenzene). Characterization of the catalyst using different spectroscopic techniques revealed that the copper metal is bound through the pyridine substructure of the polymer. The versatility of the catalyst was established by utilizing it for Chan‐Lam coupling reactions in an eco‐friendly solvent methanol. High yields of C−N cross coupled products are obtained within a short time in presence of K2CO3 and 10 weight % of the catalyst having 13.6 weight % of copper. The catalyst could be recovered after carrying out the reaction by simple filtration and reused. Additionally, among a variety of N‐functionalized products synthesized during this study, an N‐phenyl isatin derivative was found to be promising candidate as a fluorescent probe for detection of the Hg2+ ion in aqueous acetonitrile solution.

A Non-Bonding Interaction-Based Fluorescent Probe for Detection of Halogenated Carbonyl Compounds

The fluorescent detection of neutral and volatile carbonyl halogenated compounds had not been studied before. We describe here a simple and sensitive turn-on rhodamin fluorescent probe for the selective detection of fluorinated/brominated/chlorinated/iodinated carbonyl compounds. A wide range of linear or cyclic volatile organic halides was detected with a limit of detection as low as 45.6 nM within 1 min. Mechanistic experiments and DFT calculations indicate the reversible formation of a 1:1 complex of sensor and analyst through non-bonding interaction.

Metal–organic frameworks as a fluorescent probe for detection of pathogenic biomarkers in human urine

AbstractMetal–organic frameworks (MOFs) are actively explored as sensing materials owing to their high porosity, substantial surface area, and structural diversity, providing diverse chemical and physical properties. Their fluorescent characteristics are pivotal, enabling MOFs to function as probes for detecting specific target molecules. Unlike conventional disease diagnosis methods such as biopsies or blood collection, the detection of pathogenic biomarkers in human urine is conventional and less risky. While mass spectroscopy identifies proteins and metabolites in urine at high costs, MOF test papers offer a convenient solution. These papers confirm the existence of the target molecules through naked‐eye observation upon UV light irradiation at specific wavelengths. MOF‐based fluorescent probes facilitate disease diagnosis, including pheochromocytoma, toluene exposure, vitamin deficiencies, gout, hyperuricemia, cancers, body disorders, and teratogenicity, with low detection limits. This review delves into recent developments in MOF fluorescent probes, covering synthesis, emission spectra, and sensing mechanisms.

Carbazole-alt-fluorene based π-conjugated Cu(II)-metallopolymer with pendent diketopyrrolopyrrole unit as highly selective and sensitive turn-on fluorescent probe for detection of amino acids

Highly emissive and soluble poly(carbazole-alt-fluorene) (P1) based π-conjugated alternative copolymers with thiophene-diketopyrrolopyrrole as pendent unit have been designed and synthesized via Pd(0)-catalyzed Suzuki coupling polymerization from the corresponding monomers 3,6-dibromo-9H-carbazol-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole and 2,7-bis-oxaborolan-9,9-dioctylfluorene. The well-defined copolymer P1 has been characterized by multinuclear NMR spectra as well as by tetradetector GPC showing molecular weight (Mn) of 15.6 kg/mol with the polydispersity indices of 1.38. The red emissive polymer has been explored for the detection of amino acids based on a secondary ‘‘turn-on’’ sensing approach. The thiophene-diketopyrrolopyrrole anchored carbazole-alt-fluorene copolymer shows high selectivity towards Cu2+ ions by changing the emission wavelength from red to blue due to the formation of the Cu(II)-metallopolymer (P1–Cu2+). The resulting metallopolymer P1–Cu2+ exhibits high sensitivity and selectivity towards amino acids over the other biologically relevant analytes. More importantly, the P1–Cu2+ metallopolymer exhibited higher sensitivity towards glycine, with the detection limit of 90 ppb (∼1.21 × 10−6 mol/L) along with relatively higher association constant of 2.55 × 108 M−1. To comprehend the sensing mechanism through photo-induced electron transfer (PET), the detailed photophysical studies have been carried out with P1 and its representative monomeric model compound M1. Furthermore, fluorescence anisotropy study has also been carried out to inspect the molecular interactions responsible for the sensing properties of P1–Cu2+ metallopolymer towards glycine.