Dual-channel Probe Research Articles

A novel colorimetric/fluorometric dual-channel probe for selective detection of Sn2+ with long-wavelength emission and its bioimaging applications

Tin is a crucial trace element in the human body, playing a significant role in various physiological activities and overall human health. In this study, we present a novel fluorescent probe (CDM) capable of detecting Sn2+ through both colorimetric and fluorometric channels. The probe allows for visual detection by the naked eye and exhibits long-wavelength fluorescence emission. With a detection limit of 4.72 × 10−8 M and 9.95 × 10−9 M, respectively, CDM surpasses the World Health Organization's specified limit of 8.4 × 10−4 M and outperforms previously reported probes. As far as we know, this is the first fluorescent probe to enable naked-eye and long-wavelength emission-based detection of Sn2+. Additionally, a smartphone-based sensing platform was developed to recognize Sn2+. CDM not only demonstrates sensitive detection of Sn2+ in common food products but also successfully imaging Sn2+ in 4T1 cells, Caenorhabditis elegans, and mice.

Mn-modified porphyrin metal–organic framework mediated colorimetric and photothermal dual-channel probe for sensitive detection of organophosphorus pesticides

Herein, a novel dual-mode probe for organophosphorus pesticides (OPs) colorimetric and photothermal detection was developed based on manganese modified porphyrin metal–organic framework (PCN-224-Mn). PCN-224-Mn had excellent oxidase-like activity and oxidized colorless 3,3,5,5-tetramethylbenzidine (TMB) to blue–green oxidation state TMB (oxTMB), which exhibited high temperature under near-infrared irradiation. l-ascorbate-2-phosphate was hydrolyzed by acid phosphatase to produce ascorbic acid, which weakened colorimetric and photothermal signals by impacting oxTMB generation. The presence of OPs blocked the production of ascorbic acid by irreversibly inhibiting the activity of acid phosphatase, causing the restoration of chromogenic reaction and the increase of temperature. Under the optimal conditions, the probe showed a good linear response to OPs in the concentration range of 5 ∼ 10000 ng/mL, using glyphosate as the analog. The detection limits of glyphosate in colorimetric mode and photothermal mode were 1.47 ng/mL and 2.00 ng/mL, respectively. The probe was successfully used for sensitive identification of OPs residues in tea, brown rice, and wheat flour. This work proposes a simple and reliable colorimetric/photothermal platform for OPs identification, which overcomes the problem that single-mode detection probes are susceptible to external factors, and has broad application potential in the field of food safety.

Preparation and utilization of carbon dots as a nanoprobe for sensitive detection of tartrazine and palladium (II).

We prepared novel green, eco-friendly carbon dots as a dual-channel probe for highly sensitive and selective detection of tartrazine (Trz) and palladium(II) (Pd(II)) involving, respectively, FRET and electron transfer mechanisms. Furthermore, the successful utilization of the carbon dots for detecting Trz and Pd(II) in actual samples implies its potential application prospects in analysis.

Acylhydrazone Functionalized Triphenylamine-Based Fluorescent Probe for Cu2+: Tunable Structures of Conjugated Bridge and Its Practical Application.

Novel fluorescent probes were constructed for the convenient and rapid analysis of Cu2+ ions, taking advantages of the the triphenylamine backbone as chromophore and acylhydrazone group as the Cu2+ recognition site. Especially, probe T2 could act as a dual-channel probe towards Cu2+ through both fluorescent and colorimetric method. Through the fluorescent method, the detection limit of probe T2 was calculated to be as low as 90 nmol/L and there was a good linear relationship between the intensity change and the concentration of Cu2+ ions. By virtue of the two-phase liquid-liquid extraction method, probe T2 could be successfully applied in practical extraction and separation of Cu2+. Furthermore, by applying a "turn-off-turn-on" circle, compound T2 could act as a sensitive probe towards S2- anions through the indirect approach and the detection limit of complex T2-Cu2+ for S2- anion was found to be 110 nmol/L.

Benzophenoxazine-based colorimetric and fluorescent probe for highly sensitive detection of amines and food freshness

In this work, we reported a chromogenic and near infrared (NIR) region fluorogenic dual-channel probe NRB, which could visually detect gaseous amines with high sensitivity (eg. 50 and 17 ppt for methylamine (MeNH2) via naked eyes and fluorescence spectrometer respectively). It exhibited a wide fluorescent emission band extending to the NIR region with a peak at 615 nm when stimulated by the MeNH2 solution. The plausible sensing mechanism was proved by mass spectrometry, where the reaction process was based on a nucleophilic substitution between the probe and amines rather than the ester group hydrolysis. Furthermore, NRB was successfully applied to monitor the food freshness (seafood and meat food), because of its low cytotoxicity and excellent photophysical properties. It was worth mentioning that real time monitoring for food quality can be realized visually by using a 365 nm UV lamp. In addition, the probe was stable during the quality guarantee period for perishable packaged food. It was believed that the applied experiments have demonstrated the value of this probe in the practical applications for food safety.

A versatile AIE probe with mitochondria targeting for dual-channel detection of superoxide anion and viscosity

Abnormal viscosity and excessive superoxide anion (O2•-) levels in living cells often cause a series of biological dysfunction and oxidative damage. However, a great challenge remains in quickly and conveniently detecting the viscosity and O2•- levels in living cells. Herein, we fabricated a versatile aggregation-induced emission (AIE) probe with mitochondria targeting, DTPB, for dual-imaging of viscosity and O2•- level in living cells with two different channels. The obtained DTPB contained a diphenyl phosphinic acid unit responsive to O2•-, a unit with twisted intramolecular charge trans (TICT) function responsive to viscosity, and a pyridine cation unit with mitochondria targeting. The results showed that DTPB exhibited a remarkable response to viscosity with a near-infrared emission peak at 671 nm and was highly sensitive to O2•- levels with an emission peak at 587 nm. The dual-channel probe has great application prospects in the visual diagnosis of cancer and related diseases.

Fluorescent and Colorimetric Ionic Probe Based on Fluorescein for the Rapid and On-Site Detection of Paraquat in Vegetables and the Environment.

Detection of pesticide paraquat (PQ) is of considerable significance to ensure food safety, and its rapid and on-site detection is still a challenge. Aimed at the ion characteristics of PQ, an "enrichment and detection" strategy was proposed to improve the sensitivity through electrostatic attractions, and the ion characteristic of probes was adopted to increase the portability through avoiding aggregation-caused quenching effects in the paper strips. Herein, a novel anion-functionalized ionic liquid (IL) probe with a large conjugated plane and rich π-electrons ([Fluo][P66614]2) was designed as a fluorescent and colorimetric dual-channel probe to sensitively and rapidly detect trace amounts of PQ in vegetables and the environment. The proposed probe exhibited good linearity with a detection limit of 64.0 nM in the PQ concentration range of 0.3-7.0 μM (fluorometry) and 0.1 μM in that of 0.1-8.0 μM (colorimetry), respectively. In addition, it displayed a rapid fluorescence quenching response from green to dark (<5 s) and excellent anti-interference (among 23 other pesticides) due to dual effects of electrostatic attraction and π-π stacking. Most importantly, the lipophilic IL probe could be applied in real vegetables and environmental samples with a satisfying recovery rate of 98-103% and assembled into a handy paper strip that achieved the visual semiquantitative detection of PQ. This ionic probe provides a feasible approach for rapidly and conveniently detecting PQ for ensuring agricultural and food safety and opens a new avenue to detect ion-responsive analytes in real complex samples by an "enrichment and detection" strategy.

A new Fe3+-selective, sensitive, and dual-channel turn-on probe based on rhodamine carrying thiophenecarboxaldehyde: Smartphone application and imaging in living cells

A new dual-channel probe based on rhodamine B derivative (MSB) was successfully designed, synthesized, characterized by Nuclear Magnetic Resonance (NMR) Spectroscopy, Fourier Transform Infrared Spectrophotometer (FTIR), Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS), X-ray Photoelectron Spectroscopy (XPS), and Single Crystal X-rayDiffraction, and the sensing abilities toward Fe3+ cation have been demonstrated and the probe was successfully utilized for fluorescence imaging of Fe3+ in living cells. The probe demonstrated quite fast, sensitive, and selective response to Fe3+ by causing an extreme enhancement in UV–vis and fluorescence spectroscopy techniques in the buffered aqueous media which makes MSB a dual-channel probe. While the color of MSB solution was initially light yellow, it turned pink in the presence of Fe3+, which provided highly selective naked-eye determination among several ions as alkaline, alkaline-earth, and transition metal ions. After that, the probe was easily applied to paper strips and real samples such as drinking waters and supplementary iron tablets for sensing Fe3+ in an aqueous solution. The detection limit (LOD) and the response time of the probe were determined as 4.85x10-9 M and 4 min, respectively, which are quite lower compared with other rhodamine based Fe3+ sensors in the literature. According to Job’s plot, 1H NMR titration, MALDI-TOF MS, XPS, and DFT study techniques, the complexation ratio between MSB and Fe3+ was found as 1:1. Moreover, the spectral response was reversible with alternately addition of Fe3+ or Na2EDTA to the MSB solution. In addition, fluorescence imaging in NIH/3T3 mouse fibroblast cells and studies in real samples with a quite high recovery rate exhibited that the probe is qualified for detection of Fe3+ ion with multiple practical usages.

Intra-abdominal and perineal pressures during abdominal exercises: A cross sectional study in postpartum women.

Low intra-abdominal pressure (IAP) and high perineal pressure (PP) are safe conditions for pelvic floor. This study aims to measure IAP and PP in Beninese post-partum women during abdominal exercises and determine what exercise presents less risk for pelvic floor after delivery. IAP and PP were measured at rest and during exercises performed in random order: Cough, pelvic floor contraction (PFC), Curl-up, diaphragmatic aspiration (DA), Drawing-in, DA + Curl-up and Drawing-in+Curl-up, using a Micro-Full biofeedback PHENIX-Vivaltis with dual-channel probe. Results were presented as change from rest (maximal value during exercise minus value at rest) and expressed in percentage of this change for the reference exercise, Cough for IAP and PFC for PP. The ANOVA repeated measures test was used to compare pressures between exercises. Seventeen postpartum women participated to this study. The maximal IAP and PP change were the highest (100%), respectively, during cough and PFC. During DA, IAP was the lowest (-7%) and PP was 51%. During Curl-up, IAP was moderate (43%) and significantly higher than during PFC (33%), Drawing-in (16%) and DA. PP was low (29%) and similar to that during Drawing-in (23%). Compared to Curl-up, Drawing-in+Curl-up increased PP (50%) but did not decrease IAP (40%). DA + Curl-up increased PP (58%) and decreased IAP (31%) compared to Curl-up but not compared to DA. DA is safe and Curl-up presents little risk for the pelvic floor. According to interindividual variations observed in IAP and PP, intrinsic factors should be considered in future studies.

A dual-channel probe based on copper ion-mediated metal organic framework composite for colorimetric and ratiometric fluorescence monitoring ofglyphosate degradation in soil and water.

A dual-channel probe was developed, based on a novel composite metal organic frameworks (ZnMOF-74@Al-MOF) for glyphosate determination through ratio fluorescence and colorimetric methods. The prepared probe can not only recognize and combine glyphosate by introducing copper ion into the MOF, but also possess peroxidase-like catalytic activity. The recognition of target glyphosate brought about changes relative to its concentration on fluorescence intensity and ultraviolet absorption. And, the high specific surface area and porosity of porphyrin MOF provides the developed probe with more response opportunities to afford a better detection performance for glyphosate. Under optimum conditions, the copper ion-mediated method exhibited good detection performance for glyphosate with low detection limits (0.070 and 0.092μgmL-1 for fluorescence and colorimetric techniques, respectively). Furthermore, the possible mechanisms of the fluorescence quenching and the peroxidase-like catalytic of the probe were also explored. This dual-channel method was applied to monitor glyphosate degradation in environmental samples and satisfactory results were obtained.

Fluorometric/electrochemical dual-channel sensors based on carbon quantum dots for the detection and information anti-counterfeiting

Sensors used to detect Fe3+ and Cys are generally a single method. In this work, two methods of fluorescence and electrochemistry are innovatively combined to detect Fe3+ and Cys, and the obtained Lod is basically the same. Carbon quantum dots (CQDs) with blue fluorescence were successfully prepared by hydrothermal methods using tryptophan (Trp) as carbon source, which can be used for fluorescence and electrochemical dual-channel probe quickly detecting iron ion (Fe3+) and cysteine (Cys). A series of studies have been carried out on its morphology, chemical structure, and optical properties through TEM, XRD, FT-IR, XPS, UV–vis absorption spectrum, and photoluminescence spectra. And the quantum yield of CQDs was up to 52.64%. It was also analyzed in the real sample, demonstrating the feasibility and reliability of detecting Fe3+ and Cys in the real sample. Furthermore, CQDs can also be used as fluorescent ink for information anti-counterfeiting due to their excellent fluorescent properties.

Rhodamine-thiourea Linked Naphthalimide Derivative to Image ATP in Mitochondria using Two Channels.

Adenosine 5'-triphosphate (ATP), synthesized in mitochondria, is an energy molecule in all living things. ATP not only serves as an energy source for protein synthesis and muscle contraction, but also as an important indicator for various diseases, such as Parkinson's disease, cardiovascular disease, and others. Accordingly, detection and sensing of ATP, especially in mitochondria, are important. In this study, a unique ring-opening process of rhodamine was coupled to recognition of ATP via introduction of a thiourea moiety, which was further linked to a naphthalimide group. A strong fluorescent emission at ∼580 nm was accompanied by a color change from colorless to pink upon addition of ATP at pH 7.4. Fluorescent probe 1 successfully imaged mitochondrial ATP with a Pearson's coefficient of 0.8. In addition, green emission from the naphthalimide moiety at ∼530 nm was observed without any change upon addition of ATP. This emission can be considered equivalent to an internal standard to utilize probe 1 as a dual-channel probe for ATP. Furthermore, probe 1 showed negligible cytotoxicity based on MTT assays.

Up-/Downconversion Fluorescence Dual-Channel Probe Based on NaYF4: Yb/Er/Eu Nanoparticles for the Determination of Cu(II)

Copper ions [Cu(II)] are essential in many biological processes. Accurate determination of Cu(II) is of great significance for environment monitoring and diseases diagnosis. A dual-channel probe (DCP) with up/downconversion fluorescence is developed using a one-pot solvothermal method in this work. Yb(III), Er(III), and Eu(III) are doped into NaYF4 capped with ethylene imine polymer (PEI), that is, PEI-capped NaYF4: Yb(III), Er(III), and Eu(III) NPs (marked as PEI-capped NYF: Yb/Er/Eu NPs), forming the DCP to determine Cu(II) through the up- and downconversion fluorescence variations. The DCP is designed aiming to minimize mutual interference between the fluorescent signals. Under the optimized conditions, the up-/downconversion fluorescence performances of DCP are excellent, including a linear range for 30 nM–10 μM Cu(II) with the detection limits of 29.30, 18.23, and 26.04 nM (monitoring wavelengths of 545, 592, and 616 nm) as well as excellent selectivity to Cu(II). The mechanism of Cu(II) determination could be attributed to the quenching of up-/downconversion fluorescence because of the inner filter effect triggered by PEI–Cu(II) complexes. To illustrate the potential application of up-/downconversion fluorescence DCP, the concentration of Cu(II) in tap water is detected, and satisfactory results are acquired, indicating that the up-/downconversion fluorescence DCP has promising applications in the fields of food safety and environmental detection. More importantly, the proposed design idea is universal regarding the construction of other dual-channel probes for the detection of metal ions.

Colorimetric and fluorescent dual-channel sensor array based on Eriochrome Black T/Eu3+ complex for sensing of multiple tetracyclines

In this work, a dual-channel probe based on a complex of Eriochrome Black T (EBT) and Eu3+ ions (denoted as EBT/Eu3+) was used to sense four kinds of tetracyclines (TCs). UV–Vis and fluorescence spectra indicated that EBT/Eu3+ molecule has the ability to emit dual channel signals of color and fluorescence. When TCs with different structures were added to the EBT/Eu3+ solution, the color and the fluorescence intensities of EBT/Eu3+ solution varied with TCs structure. FT-IR spectra revealed that a coordinating reaction occurred between acylamino groups, hydroxyl groups of A-ring in TCs and Eu3+ ions. The coordinating ratio was 1: 2. Utilizing dual channel signals as well as the aid of principal component analysis (PCA), EBT/Eu3+ was capable of discriminating not only single TCs with concentrations in nano-molar level, but also binary mixtures of TCs. The results of controlled experiments on various interfering substances and other antibiotics proved that this method has high selectivity for TCs detection. Furthermore, this two-channel sensor array based on EBT/Eu3+ can also be used for the discrimination of unknown TCs in commercially available pork and honey with the 100% recognition accuracy. These results indicated that TCs with different structures can be rapidly discriminated by using a single and easily prepared sensor array.

A novel dual-channel probe based on acylhydrazone derivative for detection of CN− and its applicability

A novel dual-channel probe based on acylhydrazone derivative for detection of CN− and its applicability

1-Adamantanamine-based triazole-appended organosilanes as chromogenic “naked-eye” and fluorogenic “turn-on” sensors for the highly selective detection of Sn2+ ions

1-Adamantanamine based organosilanes 4a–d have been synthesized and possessed selectivity towards Sn2+ ions only and serve as a colorimetric/fluorimetric dual-channel probe. The turn-on fluorescence has been marked on interaction with Sn2+ ions.

Dual-Channel Probe of Carbon Dots Cooperating with Lanthanide Complex Employed for Simultaneously Distinguishing and Sequentially Detecting Tetracycline and Oxytetracycline.

Tetracycline (TC) and oxytetracycline (OTC) are the most widely used broad-spectrum antimicrobial agents in tetracycline drugs, and their structures and properties are very similar, so it is a great challenge to distinguish and detect these two antibiotics with a single probe at the same time. Herein, a dual-channel fluorescence probe (SiCDs@mMIPs-cit-Eu) was developed by integrating two independent reaction sites with SiCDs-doped mesoporous silica molecular imprinting group and europium complex group into a nanomaterial. The synergistic influence of inner filter effect and “antenna effect” can be guaranteed to solve the distinction between TC and OTC. Moreover, this novel strategy can also sequentially detect TC and OTC in buffer solution and real samples with high sensitivity and selectivity. This method revealed good responses to TC and OTC ranging from 0 to 5.5 μM with a detection limit of 5 and 16 nM, respectively. Combined with the smartphone color-scanning application, the portable and cheap paper-based sensor was designed to realize the multi-color visual on-site detection of TC and OTC. In addition, the logic gate device was constructed according to the fluorescence color change of the probe for TC and OTC, which provided the application possibility for the intelligent detection of the probe.

Simultaneous imaging of hypochlorous acid and nitric oxide in live cells based on a dual-channel fluorescent probe

Both reactive oxygen species (ROS) and reactive nitrogen species (RNS) are inevitably produced during normal human metabolism. Various ROS and RNS together form tangled networks that play important roles in many physiological and pathological processes. Here we used 1,8-naphthalene diamine as a reactive group to develop a fluorescent probe, N-[2-(6-phenylethynyl)quinolinylmethyl]-1,8-diamino naphthalene (QBN), for HOCl and NO. QBN showed a “turn-on” fluorescent response at 464 nm to HOCl in the range of 0–75 μM with rapid responding time (10 s) and detection limit (0.11 ± 0.03 μM). Furthermore, a “turn-on” fluorescent responses at 512 nm to NO in the range of 0–40 μM with responding time (20 s) and detection limit (25.7 ± 3.4 nM) was found. The response mechanisms of QBN to HOCl and NO were discussed based on mass analysis of the different products. The dual-channel probe was then successfully applied for simultaneous imaging of both exogenous and endogenous HOCl and NO in live cells.

A Highly Selective Turn-on Fluorescent and Naked-eye Colourimetric Dual-channel Probe for Cyanide Anions Detection in Water Samples.

A highly selective turn-on fluorescent and naked-eye colourimetric dual-channel probe for cyanide anions (CN-) has been designed and characterized. In the mixed solution (DMSO / H2O, 9:1, v / v), only CN- could cause an increase in the UV absorption intensity and the corresponding fluorescence intensity increased, and other anions had no significant effect on the probe. After treatment with cyanide in the probe solution, the solution showed a noticeable colour change, from light yellow to purple. Moreover, a fluorescence spectrophotometer can be used to observe that the fluorescence intensity of the solution is significantly enhanced. The response of the colourimetric and fluorescent dual-channel probe to CN- was attributed to nucleophilic addition, and the mechanism was determined by 1H NMR spectroscopy. In addition, this probe was used to detect CN- in actual water samples, including river water, drinking water, and tap water. The spiked CN- recovery rate is very high (97.2%-100.06%), and analytical precision is also very high (RSD < 2%), which shows its feasibility and reliability for detecting cyanide ions in actual water samples.

A New Molecular Probe for Colorimetric and Fluorometric Detection and Removal of Hg2+ and its Application as Agarose Film-Based Sensor for On-Site Monitoring.

A new molecule incorporating two units of 7-nitro-benzoxadiazole (NBD), bridged by m-xylylenediamine, was synthesized and characterized on the basis of analytical and spectroscopic techniques. The metal ion sensing property of this molecule was studied spectroscopically with a large number of metal ions. This study revealed that it can perform as a dual-channel probe for colorimetric as well as fluorometric detection of Hg2+. In presence of Hg2+, a substantial change in UV-Vis spectrum with the appearance of a new band at 545nm and a distinct colour change from yellow to red was observed. In the fluorescence spectrum, the intensity of the emission band was substantially quenched only upon addition of Hg2+. No significant interference from any other metal ion used in this study was noted, the limit of detection (LOD) for Hg2+ was found to be 60 and 10nM for colorimetric and fluorometric detection method, respectively. This new chemosensor was used for removal of Hg2+ from aqueous solution with 92% efficiency. For on-site monitoring and field application, this molecule was immobilized into the agarose based hydrogel film, which was used successfully for detection of Hg2+ in water. The study on reversible behaviour of this chemosensor revealed that it can be recycled in solution as well as in solid phase by treatment with Na2S.