Naphthalimide-based Fluorescent Probe Research Articles

Naphthalimide-based fluorescent probe for Hg2+ detection and imaging in living cells and zebrafish.

A simple naphthalimide-based fluorescent probe was designed and synthesized for the determination of mercury ion (Hg2+ ). The probe showed a noticeable fluorescence quenching response for Hg2+ . When added with Hg2+ , the fluorescence intensity of the probe at 560 nm was remarkably decreased with the color changed from yellow to colorless under ultraviolet (UV) light. The probe had a notable selectivity and sensitivity for Hg2+ and displayed an excellent sensing performance when detecting Hg2+ at low concentration (19.5nM). The binding phenomenon between the probe and Hg2+ was identified by Job's method and high-resolution mass spectrometry (HRMS). Moreover, the probe was not only utilized to identify Hg2+ in real samples with satisfactory results (92.00%-110.00%) but also was successfully used for bioimaging in cells and zebrafish. The recognition mechanism has been verified by transmission electron microscopy (TEM) for the first time. All the results showed that the probe could be used as a potent useful tool for detection of Hg2+ .

A ratiometric fluorescent probe for imaging the fluctuation of HOBr during endoplasmic reticulum stress.

Endoplasmic reticulum (ER) stress is closely associated with cell apoptosis, autophagy, DNA damage, metabolism, and migration. When ER stress occurs, a large number of reactive oxygen species, including hypobromous acid (HOBr), are generated. The degree of ER stress can be understood by accurately detecting the HOBr concentration in the ER. Unfortunately, no ER-targetable probes for detecting HOBr have been reported to date. To solve this problem, we developed a naphthalimide-based fluorescent probe (ER-NABr) for imaging HOBr in the ER. Upon reaction with HOBr, a red shift in the fluorescence spectrum occurs due to the difference in the molecular conjugation between the original ER-NABr and the reaction product. ER-NABr showed a fast response (within 30 s) and high selectivity towards HOBr, with a ratiometric quantitative response (5-40 μM) and high sensitivity (138 nM). With its excellent biocompatibility and remarkable ER-targetable ability, ER-NABr was successfully utilized to ratiometrically image intracellular HOBr, particularly during ER stress, which is beneficial for revealing the role of HOBr in ER-associated diseases.

Relay recognition of Cu2+ and S2− using naphthalimide-based fluorescent probe and its applications in molecular logic gate and bioimaging

A fluorescent chemosensor based on naphthalimide derivative (HL) was prepared and characterized. HL exhibited strong fluorescence emission at 528 nm, which was attributed to naphthalimide moiety, while the addition of Cu2+ almost completely quenched the fluorescence emission. However, with the addition of S2−, the fluorescence at 528 nm reoccurred remarkably. The detection limits for Cu2+ and S2− were measured to be 1.72 × 10−7 M and 2.66 × 10−7 M, respectively. As determined, the fluorescence behavior of HL in the presence of Cu2+ and S2− could be manufactured to IMPLICATION type logic gate. Moreover, confocal fluorescence imaging in HepG2 cells indicated that the HL could act as a useful fluorescent probe for intracellular Cu2+ and S2− detection with negligible cytotoxicity.

A novel naphthalimide-based fluorescent probe with sulfonyl hydrazide as receptor for detection of Cu2+

A novel fluorescent probe N'-(4-(2-butyl-1,3-dioxo-2,3-dihydro-1H-benzo[de] isoquinolin-6-yl)benzylidene)-4-methylbenzenesulfonohydrazide (ENM) that could selectively response to Cu2+, was reported in this paper, which was the first fluorescent probe with sulfonyl hydrazide as the receptor to detect Cu2+. The selectivity, concentration titration, pH titration, time dependence, detection limit and recognition mechanism of ENM for Cu2+ in CH3CN/H2O solution were investigated. It was shown that ENM exhibited high selectivity, sensitivity and fast response to Cu2+, and the detection limit was as low as 0.27 μmol/L. More importantly, the sensing mechanism was that ENM underwent decomposition reaction with the addition of Cu2+. In addition, ENM could work in a wide pH range. The results of determination of Cu2+ in water samples indicated that ENM had potential practical value in environmental analysis.

Sensitive Detection of Various Forms of Hydrogen Sulfide via Highly Selective Naphthalimide-Based Fluorescent Probe.

Hydrogen sulfide (H2S) is an important gasotransmitter, but only a few methods are available for real-time detection. Fluorescent probes are attractive tools for biological applications because of their high sensitivity, convenience, rapid implementation, noninvasive monitoring capability, and simplicity in fluorescent imaging of living cells and tissues. Herein, we report on a pro-fluorescent probe, NAP-Py-N3 based on naphthalimide derivative, which was found to show high selectivity toward H2S over various other analytes, including biothiols, making it feasible to detect H2S. After reaction with H2S, this probe showed rapid and significant turn-on green fluorescent enhancement at 553 nm (about 54-fold, k2 = 9.62 M-1s-1), high sensitivity (LOD: 15.5 nM), significant Stokes shift (118 nm), and it was found that the fluorescence quantum yield of fluorescence product can reach 0.36. Moreover, the probe has also been successfully applied to detect the gaseous H2S and to confirm the presence of H2S released from modern organic donors, which in recent years have been commonly used to investigate the role of H2S in biological systems. All the results indicate that this probe is excellent and highly valuable.

A naphthalimide-based fluorescent probe for rapid detection of nitrite and its application in food quality monitoring

Nitrite (NO2−) is a widely used food additive and long-term aging of cooked leftovers may also contribute to the formation of NO2−, excessive consumption of NO2− is harmful to human health. Developing an effective sensing strategy for on-site monitoring of NO2− has attracted considerable attention. Herein, a novel colorimetric and fluorometric probe ND-1 based on photoinduced electron transfer effect (PET) was designed for highly selective and sensitive detection of nitrite (NO2−) in foods. The probe ND-1 was strategically constructed by employing naphthalimide as the fluorophore and o-phenylendiamine as the specific recognition site for NO2−. The triazole derivative ND-1-NO2- could be produced exclusively by reacting with NO2−, leading to a visible colorimetric change from yellow to colorless accompanied by a significantly enhanced fluorescence intensity at 440 nm. The probe ND-1 exhibited promising sensing performances towards NO2− including high selectivity, rapid response time (within 7 min), low detection limit (47.15 nM) and wide quantitative detection range (0–35 μM). In addition, probe ND-1 was capable of quantitative detecting of NO2− in real food samples (including pickled vegetables and cured meat products) with satisfactory recovery rates (97.61%–103.08%). Moreover, the paper device loaded by probe ND-1 could be utilized for visual monitoring of NO2− levels variation of stir-fried greens. This study provided a feasible method for the accurate, traceable and rapid on-site monitoring NO2− in foods.

A naphthalimide-based fluorescent probe with mitochondria targeting for GSH sensing and cancer cell recognition

GSH is an important biological thiol which involves many biological processes, and also an biomarker for cancer. So it's urgent to develop fluorescent probes with excellent sensitivity and high selectivity for GSH detection. Herein, we develop a new GSH-responsive fluorescent probe TPP-Naph-SS-Fc based on PET (photoinduced electron transfer) mechanism. TPP-Naph-SS-Fc contains naphthalimide fluorephore, the ferrocene quencher, the disulfide cleavage bond and the triphenylphosphine mitochondrial localizer. It shows a fluorescence turn-on response toward GSH for cleavage the disulfide bond, which result in the blocking of PET process. Especially, this probe can localize in mitochondria and make real-time imaging of GSH, also demonstrate the ability to distinguish between cancerous and normal cells.

AIEE active J-aggregates of naphthalimide based fluorescent probe for detection of Nitrobenzene: Combined experimental and theoretical approaches for Non-covalent interaction analysis

A new naphthalimide-based fluorescent probe NS with exceptional J-aggregates based aggregation-induced emission enhancement (AIEE) properties was rationally synthesized through a single-step imidation reaction. Probe NS exhibited excellent AIEE properties in aqueous media through the formation of J-aggregates with remarkable red-shift. The AIEE active probe NS was used for selective and sensitive detection of nitrobenzene (NB) based on fluorescence quenching response. Formation of J-aggregates was assessed through fluorescence titration. These J-aggregates contributed significantly to produce favorable interaction between probe NS and NB. The highly selective fluorescence detection of NB was accredited to the adjustable smaller size of NB that can easily penetrate into interstitial spaces of probe molecules. Ability of sensor to detect NB in solid state was also accomplished through solid state fluorescence spectroscopy. Nature of interaction and sensitivity of probe NS for NB has also been investigated through 1H NMR titration and density functional theory (DFT) including non-covalent interaction (NCI), quantum theory of atom in molecule (QTAIM), electron density differences (EDD), frontier molecular orbitals (FMO) and density of states (DOS) analysis. Advantageously, probe exhibited colorimetric and vapor phase detection of NB. Moreover, probe was quite sensitive for the trace detection of NB in real samples.

Bioimaging of labile lysosomal iron through naphthalimide-based fluorescent probe

Lysosomal labile iron detection is immensely important as it is related to various diseases like Alzheimer's disease, Huntington's disease, Parkinson's disease, and cell apoptosis like ferroptosis. The fluorescent-based detection methods are preferred due to their sensitive, non-invasive, and spatial-temporal detection in biological samples. However, this remains a great challenge due to the lysosomal compartment being acidic alters the photophysical properties of the probe. Herein, we have rationally designed and synthesized multi-component naphthalimide-based fluorescent marker with preferred optical properties and bio-compatibility for selective detection of labile iron present in the lysosomal compartment. The synthesized probe was characterized structurally and optically by NMR, mass spectrometry, UV–visible, and fluorescence spectroscopy. The developed probe with an appropriate linking strategy turns out to be tolerant to fluorescence alternation in lysosomal pH. The probe exhibits great selectivity and high sensitivity for Fe(III) with limit of detection of 0.44 μM and is also able to detect Fenton-type reactions. Further, the probe has been successfully applied for lysosomal imaging and detecting labile Fe(III) present in the lysosomal lumen of the live cells.

Naphthalimide-Based Fluorescent Probe for Profiling of Aldehydes during Oxidation of Unsaturated Lipids.

A lipophilic naphthalimide hydrazine fluorescent probe was successfully developed in this study for profiling aldehyde oxidation products. Dodecyl amine was applied to afford lipophilicity of the fluorescent probe for lipids. Investigation of fluorescence properties of the probe and condensation products with typical aldehydes including MDA and hexanal revealed significant enhancement of fluorescence intensity after condensation due to the inhibition of photo-induced electron transfer. MDA and hexanal could be differentiated by the probe through emission of different fluorescence colors (blue, MDA; green, hexanal). Eight major oxidation components including seven aldehydes were detected by the fluorescent probe coupled with high-performance liquid chromatography-mass spectrometry during aerobic oxidation of typical unsaturated lipids. Formation of these aldehyde oxidation products was rationalized through the radical oxidation mechanism. Detection of representative aldehyde products demonstrated the generality in the application of this fluorescent probe for profiling of aldehydes after lipid oxidation.

A naphthalimide-based fluorescent probe for quantitative sensing of UV light

Developing ultraviolet (UV) sensors that can visualize UV light in the environment for productive life has been widely practiced. A challenging problem that arises in this domain is the quantitative analysis of UV light. In this study, we identified a novel naphthalimide derivative, NDGF, which can undergo decomposition to various degrees when irradiated by UV light with different intensities, so as to produce corresponding fluorescence intensities. Moreover, NDGF was prepared as a UV-responsive film NDGF-PEO which also has outstanding competence in the quantification of UV intensity. The surprising thing is that this novel UV-responsive decomposition mechanism of NDGF has been demonstrated and has great potential to open new doors for the development of naphthalimide-based photocages and novel UV quantitative sensors.

Hydrogen-bond activated ESIPT in naphthalimide-based fluorescent probe for sensing volatile amines

Amines levels present important indicative value in food safety and human health. Although they are involved in some normal physiological responses of the organism, their overproduction or intake may cause pathological responses. Herein, we report a recyclable visual packaging bag for volatile amines detections based on the naphthylamide derivative N-S and its positive PL characteristics. Specifically, handmade test strips based on compound N-S have been applied to fish freshness labeling, and the cyclic fumigation experiment shows its restorable PL effect and efficiency. The possible PL transfer mechanism of naphthylamide derivative N-S is uncovered by the density functional theory (DFT) calculation and titration mass spectrometer and 1H NMR. This work expands a conjugation in a molecule by hydrogen-bond activated ESIPT (H-ESIPT) and provides a portable detection method for volatile amines detection.

A novel naphthalimide-based fluorescent probe for the colorimetric and ratiometric detection of SO2 derivatives in biological imaging

SO2 is a well-known signal molecule and one of reactive sulfur species, which closely participates in many metabolic processes. While unbalanced metabolism of sulfur dioxide can lead to serious complications of various diseases. Therefore, a rapid and accurate monitoring of SO2 derivatives with high selectivity and sensitivity would be beneficial for their bio-analytic studies. Herein, a novel ratiometric fluorescent probe (NG-TCF) based on ICT mechanism for monitoring SO2 was developed. The probe underwent a nucleophilic addition of HSO3-/SO32- to give rise to a 120 nm blue-shift dual-emission signal changes in enhanced green channel and subdued red channel under a single wavelength excitation. The probe showed fast response rate (within 7 min), good sensitivity (the detection limit is 1.53 µM), and specific response toward HSO3-/SO32- over other bio-species, including H2S and ClO-. Moreover, the probe can be applied for visual ratio imaging of exogenous and endogenous SO2 derivatives in living cells.

A novel dual-capability naphthalimide-based fluorescent probe for Fe3+ ion detection and lysosomal tracking in living cells.

We design and synthesize a novel 1,8-naphthalimide-based fluorescent probe MNP that features the dual capabilities of tracking lysosomes in living HeLa cells and sensitively detecting Fe3+ ions in aqueous solution. The MNP is obtained by modifying the morpholine group with a lysosomal targeting function and the piperazine group with an Fe3+ ion recognition function on the 1,8-naphthalimide matrix. In the presence of Fe3+ ions, the MNP acts as a recognition ligand to coordinate with the central Fe3+ ion, and the protonated [MNPH]+ is eventually generated, in which significant fluorescence enhancements are observed due to the intramolecular photo-induced electron transfer (PET) process being blocked. The limit of detection of Fe3+ ions is as low as 65.2 nM. A cell imaging experiment shows that the MNP has low cytotoxicity and excellent lysosomal targeting ability. Therefore, the MNP offers a promising tool for lysosomal tracking and relevant life process research.

A Naphthalimide-Based Fluorescent Probe for the Detection and Imaging of Mercury Ions in Living Cells.

The selective and efficient monitoring of mercury (Hg2+) contamination found in the environment and ecosystem has been carried out. Thus, a new 1,8‐naphthalimide‐based fluorescent probe NADP for the detection of Hg2+ based on a fluorescence enhancement strategy has been designed and synthesized. The NADP probe can detect Hg2+ with high selectivity and sensitivity and a low detection limit of 13 nm. The detection mechanism was based on a Hg2+‐triggered deprotection reaction, resulting in a dramatic change in fluorescence from colorless to green at physiological pH. Most importantly, biological investigation has shown that the NADP probe can be successfully applied to the monitoring of Hg2+ in living cells and zebrafish with low cytotoxicity.

A Golgi Apparatus-Targeting, Naphthalimide-Based Fluorescent Molecular Probe for the Selective Sensing of Formaldehyde.

Formaldehyde (FA) is a colorless, flammable, foul-smelling chemical used in building materials and in the production of numerous household chemical goods. Herein, a fluorescent chemosensor for FA is designed and prepared using a selective organ-targeting probe containing naphthalimide as a fluorophore and hydrazine as a FA-binding site. The amine group of the hydrazine reacts with FA to form a double bond and this condensation reaction is accompanied by a shift in the absorption band of the probe from 438 nm to 443 nm upon the addition of FA. Further, the addition of FA is shown to enhance the emission band at 532 nm relative to the very weak fluorescent emission of the probe itself. Moreover, a high specificity is demonstrated towards FA over other competing analytes such as the calcium ion (Ca2+), magnesium ion (Mg2+), acetaldehyde, benzaldehyde, salicylaldehyde, glucose, glutathione, sodium sulfide (Na2S), sodium hydrosulfide (NaHS), hydrogen peroxide (H2O2), and the tert-butylhydroperoxide radical. A typical two-photon dye incorporated into the probe provides intense fluorescence upon excitation at 800 nm, thus demonstrating potential application as a two-photon fluorescent probe for FA sensing. Furthermore, the probe is shown to exhibit a fast response time for the sensing of FA at room temperature and to facilitate intense fluorescence imaging of breast cancer cells upon exposure to FA, thus demonstrating its potential application for the monitoring of FA in living cells. Moreover, the presence of the phenylsulfonamide group allows the probe to visualize dynamic changes in the targeted Golgi apparatus. Hence, the as-designed probe is expected to open up new possibilities for unique interactions with organ-specific biological molecules with potential application in early cancer cell diagnosis.

Novel Mitochondria-Targeting and Naphthalimide-based Fluorescent Probe for Detecting HClO in Living Cells.

As a key reactive oxygen species (ROS), hypochlorous acid (HClO) plays an important role in many physiological and pathological processes. The mitochondria-targeting probes for the highly sensitive detection of HClO are desirable. In present work, we designed and synthesized an original mitochondria-localizing and turn-on fluorescent probe for detecting HClO. 4-Aminonaphthalimide was employed as the fluorescent section, the (2-aminoethyl)-thiourea unit was utilized as a typical sensing unit, and the quaternized pyridinium moiety was used as a mitochondria-targeted localization group. When HClO was absent, the probe showed weak fluorescence. In the existence of HClO, the probe revealed a blue fluorescence. Moreover, the turn-on fluorescent probe was able to function in a broad pH scope. There was an excellent linearity between the fluorescence emission intensity at 488 nm and the concentrations of HClO in the range of 5.0 × 10–7 to 2.5 × 10–6 mol·L–1. Additionally, the probe had almost no cell toxicity and possessed an excellent mitochondria-localizing capability. Furthermore, the probe was able to image HClO in mitochondria of living PC-12 cells. The above remarkable properties illustrated that the probe was able to determine HClO in mitochondria of living cells.

A Fluorescent Probe for the Specific Staining of Cysteine Containing Proteins and Thioredoxin Reductase in SDS-PAGE.

A naphthalimide-based fluorescent probe, Nap-I, with iodoacetamide as the alkylating group, has been synthesized, and its specific fluorescent staining of proteins containing cysteine (Cys) and selenocysteine (Sec) residues in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) has been evaluated. This molecule shows good fluorescence properties in the labeling of protein Cys/Sec residues, while reducing steric hindrance and minimizing changes in the water solubility of proteins. Reaction parameters, such as labeling time and pH, have been investigated, and the optimal labeling conditions for Cys-containing proteins have been determined. Thioredoxin reductase (TXNRD) is best stained at low pH. The probe Nap-I has been successfully used for the quantification of serum proteins and hemoglobin in Tan sheep serum, and TXNRD in Tan sheep liver and muscle has been labeled at low pH. Based on the probe Nap-I, we have also distinguished TXNRD1 and TXNRD2 by SDS-PAGE. The results showed that, compared with the normal microenvironment in which the protein resides, the lower the pH value, the greater the TXNRD activity.

A novel hydrophilic fluorescent probe for Cu2+ detection and imaging in HeLa cells.

Copper is an essential element in living systems and plays an important role in human physiology; therefore, methods to detect the concentration of copper ions in living organisms are important. Herein, we report a highly water-soluble naphthalimide-based fluorescent probe that can be used for the detection of Cu2+. The probe, BNQ, has high selectivity and sensitivity. The fluorescence intensity of the probe at 520 nm was visible to the naked eye under a UV lamp; upon the gradual addition of Cu2+, there was a colour change from green to nearly colourless. Furthermore, the detection limit of BNQ for Cu2+ was 45.5 nM. The detection mechanism was investigated using a Job's plot and density functional theory (DFT) calculations. In addition, owing to great biocompatibility, we were able to successfully use BNQ to detect Cu2+ in living HeLa cells with low toxicity.

A 3,5-dinitropyridin-2yl substituted naphthalimide-based fluorescent probe for the selective detection of biothiols and its application in cell-imaging.

A naphthalimide-based fluorescent probe was developed for the sensitive and selective detection of biothiols. The fluorescence of the probe was quenched by the electron-withdrawing 3,5-dinitropyridin-2-yl group via the photoinduced electron transfer process, and turned on by biothiol-triggered nucleophilic aromatic substitution. The sensing mechanism was confirmed by HPLC analysis and theoretical calculations. The probe shows a satisfactory response time of 30 min with low detection limits (Cys: 0.32 μM; Hcy: 0.88 μM; GSH: 0.46 μM). Furthermore, the probe was successfully utilized to detect endogenous and exogenous biothiols in HeLa cells.