Effective Fluorescent Probe Research Articles

A porphyrin-based colorimetric and near infrared fluorescent probe for reversible and rapid detection of diethyl chlorophosphate

Given the extremely high toxicity of nerve agents, developing methods for their detection with high sensitivity and specificity is of great significance. In this study, we present single pyridyl-porphyrin (TPPyP) as an effective fluorescent probe for the reversible and rapid detection of the nerve agent simulant diethyl chlorophosphate (DCP). The probe demonstrates excellent spectral properties, with DCP rapidly reacting with the pyridine and pyrrole groups on TPPyP, leading to an enhanced intramolecular charge transfer (ICT) effect. This results in a distinct color change from pink to bright green, accompanied by a gradual disappearance of red fluorescence, all occurring within 35 seconds. Furthermore, the probe can be retrieved from the detection solution by introducing triethylamine, allowing for reversible detection of DCP. Additionally, TPPyP-loaded filter paper serves as a convenient tool for visualizing gaseous DCP. In solution, the probe exhibits sensitive detection capabilities, and when applied to DCP vapor detection, the filter paper shows a color transition and a reduction in red fluorescence that can be quantitatively analyzed using a smartphone application. The green-to-red ratio (G/R) correlates linearly with DCP concentrations in the range of 0–14 ppm, showcasing the probe's potential for field applications. Selectivity and anti-interference tests reveal that only DCP affects the probe's response, confirming its robustness against common interferents. Overall, this TPPyP-based probe offers a rapid, sensitive, and portable solution for detecting nerve agents, with promising implications for environmental monitoring.

Short-Peptide-Modified Copper Nanoclusters as a Fluorescent Probe for the Specific Detection of Ascorbic Acid.

Metal nanoclusters assembled using short peptides as templates exhibit significant potential for development and application in the fields of catalysis and biomedicine, owing to their distinctive electronic structure, favorable optical properties, and biocompatibility. Among them, tripeptides exhibit a simpler structure and greater flexibility, enabling them to readily co-assemble with other functional components to create novel materials with significant application value. They can be assembled with copper ions to synthesize highly efficient luminescent nanoclusters, which can serve as an effective fluorescent probe. Here, we report a method for the synthesis of copper nanoclusters (Cu NCs) using tripeptides as templates, which also act as stabilizers and reducing agents. The synthesis conditions and properties were explored and optimized. Under optimal conditions, the Cu NCs exhibit excellent stability and are strongly fluorescent. The Cu NCs can detect 0.1-1.0 μmol/L of ascorbic acid with a low detection limit of 0.075 μmol/L, demonstrating high sensitivity and offering significant application potential for the trace of ascorbic acid in various substances. It also provides new ideas for the assembly of metal nanoclusters and the construction of fluorescent probe sensing platforms.

Novel Anthracene-Appended Calix[4]triazacrown-5 as an Effective Fluorescence Probe for Co2+ and Hazardous Cr2O7 2- Ions.

A new calix[4]triazacrown-5-derived fluorescence chemosensor (AntUr-AzClx) at cone conformation was synthesized to afford an effective fluorescent probe, which enables an enhancement in the fluorescence intensity specifically in the presence of Co2+ metal ions as well as a turnoff response for hazardous dichromate anions. 1H-NMR, 13C-NMR, ESI-MS, and elemental analysis techniques were used to characterize the structure of the anthracene-appended calix[4]triazacrown-5 (AntUr-AzClx). The metal ion-binding ability of AntUr-AzClx was evaluated against Co2+, Ba2+, Ni2+, Pb2+, and Zn2+ ions. On the basis of various metal ion recognition phenomena, AntUr-AzClx exhibited outstanding selectivity for only the Co2+ ion among other metal ions. Also, the calix[4]triazacrown-5-derived fluorescence chemosensor showed high sensitivity towards the Co2+ ion with a very low limit of detection (LOD) 0.142 μmol L-1. In addition, anion binding abilities of AntUr-AzClx against various anions such Cr2O7 2-, HCO3 -, CO3 2-, NO3 -, SO3 2-, SO4 2-, N3 -, F-, and I- demonstrated that AntUr-AzClx enables selective and highly sensitive detection of the Cr2O7 2- anion with an excellent LOD of 4.182 nmol L-1 in DMF/PBS (1/1, v/v; pH: 7.05). Furthermore, the calix[4]triazacrown-5-derived fluorescence chemosensor displayed a significant sensing behavior to detect the presence of dichromate anions even in real samples.

A highly effective curcumin-based fluorescent probe with single-wavelength excitation for simultaneous detection and bioimaging of Cys, Hcy and GSH

Cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) act as significant roles in many physiological processes, and their abnormal proliferation will cause multiple diseases including Alzheimer’s disease, Parkinson’s disease, Cardiovascular disease, atherosclerosis, and soft tissue damage. However, It is challenging work to develop a efficient method for differentiating and detecting GSH, Cys and Hcy because of their significant similarity in structures and functions. In this work, a smart fluorescent probe FBCN based on curcumin was rationally devised and developed by etherifying the phenol hydroxyl group on FBC with NBD-Cl, which emitted strong green at 516 nm. FBCN distinguished Hcy from Cys/GSH with naked eyes based on the color variation of probe solution in sunlight. Meanwhile, GSH induced the powerful fluorescence quenching of probe solution, but the fluorescence color of FBCN solution transformed from green to luminous yellow accompanied with emission wavelength redshifted from 516 nm to 540 nm or 553 nm in the existence of Hcy and Cys, respectively. Probe FBCN had outstanding sensitivity and anti-interference, low detection limit (56.5 nM, 77.7 nM, and 288 nM corresponded to Cys, Hcy, and GSH, respectively), short response time (the response time of FBCN to Cys, Hcy and GSH was 1 min, 2 min and 5 min, respectively). The DFT calculation and HRMS had verified the sensing mechanism of FBCN to biothiols. In addition, the probe was successfully utilized to detect three biothiols levels in living cell and zebrafish.

Regulating intermolecular hydrogen bonding to construct solvation-induced emission shift quinoline derivatives for real-time monitoring of water content in organic solvents

Water constitutes the most prevalent impurity in organic solvents, exerting significant influence on chemical reactions and potentially leading to fires and explosions, even in minute quantities. Thus, the development of convenient, rapid, and cost effective fluorescent probes for real-time monitoring of water content in organic solvents is imperative. Although some fluorescent materials have been synthesized for this purpose, most suffer from laborious preparation processes and poor cycling performance, constraining their practical application. This study investigates the impact of hydrogen bonding on the aggregation-induced emission (AIE) properties of quinoline derivatives, leveraging quinoline as the foundational scaffold and its nitrogen atom as the hydrogen bond acceptor. Research findings elucidate that intermolecular hydrogen bonding of quinoline is the primary determinant of their AIE behaviors. By harnessing the phenomenon of water molecules forming intermolecular hydrogen bonds with quinoline nitrogen atoms, we devised a straightforward and rapid method to fabricate a fluorescent test paper for real-time monitoring of water content in organic solvents. Experimental results demonstrate that even minute changes in water content, down to concentrations as low as 0.5 % by volume in organic solvents, can induce fluorescence changes in the test paper, which also exhibits favorable cycling performance. This study not only explores the influence of hydrogen bonds on the AIE properties of quinoline derivatives but also pioneers the development of a cost-effective, rapid, and recyclable test paper for real-time monitoring of water content fluctuations in organic solvents.

A Strategy for Rapid Synthesis of Carbon Nanodots with Reversible Photoluminescence Switching for Sensitive Dynamic Anti‐Counterfeiting

AbstractCarbon nanodots (CDs) possess exceptional fluorescence properties, which have been extensively studied in the fields of fluorescence detection and anti‐counterfeiting information. However, the exploration of CDs with simple and fast synthesis paths, secure, and efficient encryption properties, remains a challenge. The rapid synthesis of orange CDs (O‐CDs) is reported with a high photoluminescence quantum yield (PLQY) of 57.6% within 10 min at atmospheric pressure using a one‐step pyrolysis method. The O‐CDs exhibit a dual‐emission property, with a blue emission peak at 425 nm and a strong orange emission peak at 590 nm. The dual‐emission peaks of O‐CDs can allow for fast orange/blue switching of fluorescence color with changes in the acid‐base environment. O‐CDs can serve as effective fluorescent probes for pH detection, depending on their fluorescence wavelength and intensity. Additionally, O‐CDs have potential for fluorescence anti‐counterfeiting. When exposed to NH3 gas, O‐CDs fluorescent ink rapidly (1 s) transitions from orange fluorescence to blue fluorescence, and then quickly (4 s) reverts back to orange fluorescence when the gas environment changes to HCl gas atmosphere. Thus, O‐CDs fluorescent inks offer several advantages, including high fluorescence intensity, fast response, recyclability, and lossless encryption/decryption in “on‐off‐on” double encryption anti‐counterfeiting.

Lipid droplets and gallbladder targeted fluorescence probe for ratiometric NO imaging in gallstones disease models

Gallstones are a common disease worldwide, often leading to obstruction and inflammatory complications, which seriously affect the quality of life of patients. Research has shown that gallstone disease is associated with ferroptosis, lipid droplets (LDs), and abnormal levels of nitric oxide (NO). Fluorescent probes provide a sensitive and convenient method for detecting important substances in life systems and diseases. However, so far, no fluorescent probes for NO and LDs in gallstone disease have been reported. In this work, an effective ratiometric fluorescent probe LR-NH was designed for the detection of NO in LDs. With an anthracimide fluorophore and a secondary amine as a response site for NO, LR-NH exhibits high selectivity, sensitivity, and attractive ratiometric capability in detecting NO. Importantly, it can target LDs and shows excellent imaging ability for NO in cells and ferroptosis. Moreover, LR-NH can target the gallbladder and image NO in gallstone disease models, providing a unique and unprecedented tool for studying NO in LDs and gallbladder.

Simple isomeric pyridine-based fluorescence-off probes for in vitro monitoring γ-glutamyltranspeptidase activity: Design, synthesis and application

γ-Glutamyltranspeptidase (GGT) is a cell surface-associated enzyme, which has been proven to be closely related to many diseases. Thus, development of simple and effective GGT-activatable fluorescent probes for early diagnosis of diseases is of great significance. Herein, a series of simple isomeric pyridine-based GGT-activatable fluorescent probes has been successfully designed and synthesized. The preliminary experimental results indicate that Py-GGT-1 has a significant fluorescence response to GGT via a rare fluorescence-off approach. Further fluorescence response experiments, such as the time-/dose-dependent fluorescence change and the selectivity/specificity estimation, reveal that Py-GGT-1 has an excellent ability to monitor endogenous GGT activity. Mechanism studies through HRMS analysis, DFT calculations and molecular docking have theoretically verified the catalytic process between Py-GGT-1 and GGT. To develop its practical application, live-cell imaging and serum-sample analysis were carried out, demonstrating that Py-GGT-1 coud effectively track GGT within cells and organisms. Based its high selectivity and reasonable sensitivity, we expect that the probe will be applied in clinical diagnosis of GGT-related diseases in the future.

Design of new boron-doped carbon dots for nano-level assay of nebivolol in human plasma and commercial products; Application to greenness assessments

Recently, nanomaterials have attracted a lot of attention due to their potential as effective fluorescent nano-sensor probes. They were distinguishing substitutes for other luminescent techniques, such as fluorescent dyes and luminous derivatization, because of their affordability, environmental friendliness, and special photocatalytic properties. In the suggested work, a straightforward method was used to create boron and nitrogen carbon dots (B@CDs) with a good quantum yield value of 31.15 % utilizing boric acid and di-sodium EDTA. For the purpose of characterizing QDs, a variety of instruments were employed, such as transmission electron microscopy, fluorescence spectroscopy, X-ray FTIR, and UV–VIS spectroscopy. Nebivolol (NEB) is a cardiovascular medication used globally to treat congestive heart failure and hypertension, is in the meantime. For this reason, a brand-new, environmentally friendly analytical technique was created to determine the amount of human plasma, uniformity test, and commercial nebivolol (NEB) tablets. After gradually adding NEB, the response of B@CQDs was enhanced at 438 nm (excitation at 371 nm). The calibration graph ranged between 20 and 500 ng mL−1 with a quantification limit (LOQ) of 2.50 ng mL−1 and a detection limit (LOD) of 0.82 ng mL−1.

Binuclear TbⅢ complex used for the fluorescent detection of 2, 6-pyridindicarboxylic acid, an anthrax biomarker

Anthrax is a potentially highly lethal acute infectious disease caused by the zoonotic bacterium Bacillus anthracis, which poses a threat to human life and health. 2, 6-Pyridinedicarboxylic acid (DPA) is a significant component of bacterial spores as a typical anthrax biomarker. Therefore, it is imperative to develop a simple and efficient detection method for DPA. Here, we successfully synthesized a binuclear terbium complex with formulas [Tb2(DMOMP)2(CH3OH)2(H2O)4Cl2]·2Cl·2CH3OH, which is constructed by 2, 6-dimethoxy-4-methylphenol (DMOMP) and TbⅢ ion. Each TbⅢ ion center is encapsulated by seven O atoms and one Cl− anion. Based on this, the encapsulated coordination environment facilitated efficient ligand energy transfer via the “antenna effect”. Therefore, the complex exhibits interesting luminescence response characteristics, with fast and stable green fluorescence response to DPA, low detection limit Ksv = 1.08 × 10−5 M−1, and fluorescence lifetime τ = 754.93 μs. [Tb2(DMOMP)2(CH3OH)2(H2O)4Cl2]·2Cl·2CH3OH has excellent fluorescence properties and strong immunity to interference and is capable of sensitively detecting the B. anthracis biomarker DPA, allowing it to be potentially used as an effective fluorescent probe and providing a viable strategy for effective anthrax fever prevention.

A novel colormetric and light-up fluorescent sensor from flavonol derivative grafted cellulose for rapid and sensitive detection of Hg2+ and its applications in biological and environmental system

Mercury ion (Hg2+) is one of harmful heavy metal ions that can accumulate inside the human organism and cause some health problems. In the article, a highly effective fluorescent probe named EC-T-PCBM was prepared by grafting flavonol derivatives onto ethyl cellulose for the specific recognition of Hg2+. EC-T-PCBM exhibited a remarkable fluorescence light-up response toward Hg2+ with excellent sensitivity. EC-T-PCBM possessed several prominent sensing properties for Hg2+, such as low detection limit (43.9 nM), short response time (5 min), and wide detection pH range (6–9). The response mechanism of EC-T-PCBM to Hg2+ has been verified through 1H NMR titration and DFT computation. Additionally, EC-T-PCBM not only can be used for accurately determining trace amount of Hg2+ in actual environmental water samples, but also can serve as a portable and rapid device by loading it on test strips for sensitive and selective visualization of Hg2+. More importantly, the confocal fluorescence imaging of onion cells suggested the favorable cell membrane permeability of EC-T-PCBM and its prominent ability to continuously monitor the enrichment from Hg2+ within fresh plant tissues.

A o-phenanthroline-based metal-organic framework for fluorescence sensing toward CrVI and antibiotics in aqueous phase

Herein, a novel o-phenanthroline-based ligand involving two naphthalenecarboxylate groups was first synthesized, and successfully employed to fabricate a fluorescent metal–organic framework 1 under solvothermal conditions. According to the single-crystal X-ray analysis of compound 1, the Cd(II) ions connected by organic ligands form a 2D layer structure with a unique metallacycle building unit, and adjacent 2D layers are further stacked into a 3D porous framework via numerous supramolecular interactions. Powder X-ray diffraction revealed that 1 exhibits exceptional stability in both water and common organic solvents. The fluorescence sensing experiments conducted with compound 1 toward anions and antibiotics, demonstrated its selective detection capabilities for CrVI anions (CrO42−/Cr2O72−) and nitrofuran antibiotics in aqueous solutions. Additionally, fluorescent 1 serves as an effective fluorescent probe for sensing nitro-aromatic compounds in dimethyl sulfoxide. Its robust anti-interference properties, recyclability, and resistance to water make compound 1 a promising candidate for pollutant detection in wastewater.

Rational design of an iminocoumarin-based fluorescence probe for peroxynitrite with high signal-to-noise ratio.

As a high reactive oxygen species (ROS) and a reactive nitrogen species (RNS), peroxynitrite anion (ONOO- ) is widely present in organisms and plays influential roles in physiological and pathological processes. It is of great significance to develop effective fluorescent probes for imaging peroxynitrite variation in living systems. Herein we present a novel fluorescent probe TQC0 for monitoring ONOO- based on the iminocoumarin platform, and this probe was synthesized by the knoevenagel condensation between a dihydropyridine-salicylaldehyde derivative and 2-benzothiazole-acetonitrile, and subsequently masked with the boronate moiety. The obtained probe TQC0 exhibited a high signal-to-noise ratio (206-fold) and a quick 'turn-on' response (about 10min) with great selectivity and sensitivity. Furthermore, the probe TQC0 was successfully applied for imaging ONOO- in living cells with low cytotoxicity.

AI-driven precision subcellular navigation with fluorescent probes.

Precise navigation within intricate biological systems is pivotal for comprehending cellular functions and diagnosing diseases. Fluorescent molecular probes, designed to target specific biological molecules, are indispensable tools for this endeavor. This paper delves into the revolutionary potential of artificial intelligence (AI) in crafting highly precise and effective fluorescent probes. We will discuss how AI can be employed to: design new subcellular dyes by optimizing physicochemical properties; design prospective subcellular targeting probes based on specific receptors; quantitatively explore the potential chemical laws of fluorescent molecules to optimize the optical properties of fluorescent probes; optimize the comprehensive properties of the probe and guide the construction of multifunctional targeting probes. Additionally, we showcase recent AI-driven advancements in probe development and their successful biomedical applications, while addressing challenges and outlining future directions towards transforming subcellular research, diagnostics, and drug discovery.

Bismuth-doped carbon quantum dots as an effective fluorescent probe for metronidazole detection through inner filter effect, cytotoxicity studies, and bioimaging in Zebrafish

Herein we report that Walnut Shell-derived bismuth-doped Carbon Quantum Dots (Bi-CQDs) in rice morphology with an average size of 3–4 nm were used for the highly selective nanomolar (nM) detection of metronidazole (MNZ) through the inner filter effect (IFE). The excitation-dependent Bi-CQDs show high selectivity, sensitivity, and fluorescence detection on different pH (1 → 13) with a limit of detection (LoD) of 15.72 nM (R2 = 0.99092). The fluorescence quenching mechanism was evaluated by the interaction of Bi-CQSs with various MNZ concentrations (200 nM–2 μM), with binding constant as Ka = 1.081 × 10−3 M−1, increase in fluorescence lifetime values (5.60 → 5.88 ns). The interference studies, the effect of pH, the effect of time on MNZ detection, and the stability of the Bi-CQD•MNZ complex were also investigated. Further, in vitro bioimaging of Zebra fish and cytotoxicity studies were also conducted. Fluorescence imaging of Bi-CWDS in Zebra fishes distinguishes the morphology changes and embryogenesis. These results suggest that the developed sensor is highly biocompatible for fluorescence sensing and biological applications.

Unraveling the dual sensing mechanism of hydrogen peroxide probe: Photoinduced electron transfer and unusual local excited state intramolecular proton transfer

An understanding of hydrogen peroxide's (H2O2) sensing process is crucial for the development of effective fluorescent probes. In this investigation, we unraveled the sensing mechanism of the H2O2 fluorescent probe (BBD) derived from phthalimide-borate. The fluorescence of probe BBD is quenching and our findings establish this phenomenon can be attributed to a nonclassical photoinduced electron transfer (PET) process, wherein a crossing of energy curves between the local excited and charge transfer states is observed. The reaction between BBD and H2O2 causes the phenylboronic acid ester to oxidize and release a hydroxyl group, which turns off the PET process and causes the product HMD to enhance the fluorescence significantly. In addition, the results show that the generated HMD-N likewise undergoes fluorescence quenching, and the fluorescence band seen in the experiment originates from the HMD-T created by the unusual local excited state intramolecular proton transfer (ESIPT) process. In conclusion, our theoretical findings provide a comprehensive explanation for the fluorescence characteristics exhibited by BBD and HMD with an unusual local ESIPT combined PET process.

Green synthesis of fluorescent carbon dots from discarded cigarette butts as an effective fluorescence probe for sensing iron ions

A green synthesis method for preparing fluorescent carbon dots (CDs) from discarded cigarette butts was described. This method reduces costs and environmental pollution and is fully in line with the development of green chemistry. The as-synthesized CDs can be designed as a fluorescent probe for detecting iron ions (Fe3+) with highly selective and sensitive detection in the range of 0.5–800 μM. The reliability of the proposed probe was studied using tap water as a real sample, and satisfactory results were obtained.

One-Pot Hydrothermal Synthesis of mSiO2-N-CDs with High Solid-State Photoluminescence as a Fluorescent Probe for Detecting Dopamine

An effective fluorescent probe (mSiO2-N-CDs) was prepared by embedding N-CDs into mesoporous silica via a simple one-pot hydrothermal reaction and applied to the detection of dopamine (DA). Mesoporous silica not only provided a skeleton to prevent the aggregation of N-CDs but also a medium for the centrifugal collection of N-CDs, avoiding the need for dialysis and freeze-drying. The formation process, phase composition, morphology, and luminescence properties of the composite were studied in detail. The synthesized mSiO2-N-CDs possessed spherical morphology, a smooth surface, and a diameter of approximately 150 nm. The fluorescence results indicated that mSiO2-N-CDs emitted intense blue color fluorescence at 465 nm under the optimal excitation of 370 nm. Because the mesoporous silica effectively inhibited the self-quenching caused by the aggregation of N-CDs, the quantum yield of solid mSiO2-N-CDs powder reached 32.5%. Furthermore, the emission intensity of the solid mSiO2-N-CDs remained constant for 28 days. The good sensitivity and selectivity of mSiO2-N-CDs for DA enabled the establishment of a rapid, simple, and sensitive DA detection method. The linear range was 0–50 µM and the limit of detection was calculated to be 107 nM. This method was used for the determination of DA in urine, with recovery rates ranging between 98% and 100.8%. In addition, the sensing mechanism was characterized by fluorescence lifetime decay and UV–VIS spectral analysis.

Thiophene-conjugated benzothiazole derivatives as versatile skeletons for staining subcellular organelles in living cells

A series of hydroxy thiophene-conjugated benzothiazole derivatives (HTBs) was prepared to investigate their fluorescence emission behaviors and capability to selectively stain subcellular organelles for fluorescence imaging. The HTB derivatives exhibited excited-state intramolecular proton transfer (ESIPT) and intramolecular charge transfer (ICT) behaviors, according to their molecular structure. Subtle changes in the molecular structure of the HTB influenced its response to changes in the surrounding environment, such as the solvent polarity and/or pH. In vitro cellular imaging experiments revealed that HTBA (5-(benzo[d]thiazol-2-yl)-[2,2′-bithiophen]-4-ol) could selectively stain mitochondria. In contrast, HTBB-CO2Et (ethyl 5'-(benzo[d]thiazol-2-yl)-3′-hydroxy-[2,2′-bithiophene]-5-carboxylate), which contains a regioisomeric hydroxy thiophene unit with an electron-withdrawing ethyl ester group, showed the capability to stain lipid droplets (LDs) in living cells. When the hydroxyl group in HTBB-CO2Et was protected with a benzyl group, effective staining of LDs in live cells was achieved. Thus, we successfully obtained an effective fluorescent probe. Collectively, the results indicated that small structural changes resulted in substantial changes in the intracellular localization and in vitro imaging ability of the prepared compounds.

Functionalized Fluorescent Organic Nanoparticles Based AIE Enabling Effectively Targeting Cancer Cell Imaging.

We report a fluorescent dye TM by incorporating the tetraphenylethylene (TPE) and cholesterol components into perylene bisimides (PBI) derivative. Fluorescence emission spectrum shows that the dye has stable red emission and aggregation-induced emission (AIE) characteristics. The incorporation of cholesterol components triggers TM to show induced chirality through supramolecular self-assembly. The cRGD-functionalized nanoparticles were prepared by encapsulating fluorescent dyes with amphiphilic polymer matrix. The functionalized fluorescent organic nanoparticles exhibit excellent biocompatibility, large Stokes' shift and good photostability, which make them effective fluorescent probes for targeting cancer cells with high fluorescence contrast.