Fluorescent Sensor For Selective Detection Research Articles

Synthesis of graphene quantum dots inside a nanoreactor for fluorescence detection of dopamine

A label-free fluorescence sensor for selective detection of dopamine (DA) was developed by using graphene quantum dots (GQDs) as fluorescence probes. The GQDs were prepared via a top-down acid vapor oxidation strategy, in which a hollow carbon @ mesoporous silica nanosphere (h-C@mesoSiO2) serves as nanoreactor and only 1 mL of HNO3 was used as scissors for quickly cleaving the thin carbon layer in the nanospace of h-C@mesoSiO2. The method not only effectively avoids a tedious separation process but also endows GQDs with uniform size and good dispersion. And the as-prepared GQDs display good linear fluorescence response to DA in the range of 0.24–5.86 mM with a low detection limit of 12.7 nM. The proposed sensor shows high selectivity and satisfying recovery for DA detection in human urine. The good specificity toward DA may be due to a) the carboxyl groups on the surface of GQDs can interact with the amine functional groups in DA through electrostatic interactions and b) this specificity is further enhanced by the π–π interaction between GQDs and DA. Importantly, the work not only provides an avenue for the controllable synthesis of GQDs, but also expands the application of GQDs prepared by top-down method to DA sensor.

Four Ca(II)-Ln(III) bimetallic luminescent coordination polymers for sensing Fe(III) ions

We successfully prepared four Ca(II)-Ln(III) bimetallic complexes using rare earth metal (Eu, Tb) and alkaline earth metal Ca(II) under solvothermal conditions. A series of characterizations, such as XRD, IR, TGA, and solid-state fluorescence were carried out on these six crystalline materials. The single crystal test shows that all complexes are three-dimensional structures. The stability of the complex in H2O, MeOH, EtOH, and DMF solutions was studied. And the sensing effect of these complexes on metal ions (Fe2+, Cu2+, Cd2+, Mg2+, Ni2+, Co2+, Ca2+, Ba2+, Sr2+, Li+, Na+, K+, Al3+, Pb2+, Cr3+, Mn2+ and Zn2+) in aqueous solutions was studied. The results indicate that Fe(III) ions have a fluorescence quenching effects on 1-4, with high selectivity and sensitivity. The KSV values of the complexes 1-4 for Fe(III) ions are 1.77×105 (1), 6.35×104 (2), 2.25×105 (3), 5.41×104 (4), respectively, which indicated that 1-4 could be used as a fluorescent sensor for selective detection of Fe(III) ions.

A Prompt Study on Recent Advances in the Development Of Colorimetric and Fluorescent Chemosensors for "Nanomolar Detection" of Biologically Important Analytes.

Fluorescent and colorimetric chemosensors for selective detection of various biologically important analytes have been widely applied in different areas such as biology, physiology, pharmacology, and environmental sciences. The research area based on fluorescent chemosensors has been in existence for about 150years with the development of large number of fluorescent chemosensors for selective detection of cations as metal ions, anions, reactive species, neutral molecules and different gases etc. Despite the progress made in this field, several problems and challenges still exist. The most important part of sensing is limit of detection (LOD) which is the lowest concentration that can be measured (detected) with statistical significance by means of a given analytical procedure. Although there are so many reports available for detection of millimolar to micromolar range but the development of chemosensors for the detection of analytes in nanomolar range is still a challenging task. Therefore, in our current review we have focused the history and a general overview of the development in the research of fluorescent sensors for selective detection of various analytes at nanomolar level only. The basic principles involved in the design of chemosensors for specific analytes, binding mode, photophysical properties and various directions are also covered here. Summary of physiochemical properties, mechanistic view and type of different chemosensors has been demonstrated concisely in the tabular forms.

Non-aromatic single amino acid, lysine: A simple fluorescence sensor for selective detection of Cu2+ and Co2+ with colorimetric distinction by the virtue of its self-aggregation behaviour

Non-aromatic amino acids are mostly considered as non-emissive due to their lack of conventional fluorophores. However, at high concentrations, they can undergo conformational rigidification via self-aggregation and emit in the visible range. Herein, we have exploited that very property of non-aromatic amino acids as a fluorescence sensor. To the best of our knowledge, this is the first report demonstrating a single unmodified non-aromatic amino acid, Lysine (Lys) as a selective and sensitive fluorescence sensor for the detection of Cu2+ and Co2+ along with colorimetric distinction. An as-prepared aqueous solution of Lys (6.8 mM) served as a fluorescence sensor for Cu2+ and Co2+ with a detection limit of 420 nM and 460 nM, respectively in water. The instantaneous appearance of blue and pink color upon adding Cu2+ and Co2+, respectively to the Lys solution makes the system useful for their real-time analysis. The sensing of Cu2+ and Co2+ are also demonstrated through the fabrication of paper strips. Moreover, the sensor could detect Cu2+ and Co2+ in real water samples (lake water and tap water). The exceptionally low cost (<1 U.S. cent/10 mg Lys), reversibility of the sensor, and its ease of use uniquely qualify Lys as a remarkably simple fluorescent sensor.

Synthesis and Computational Study of an Optical Fluorescent Sensor for Selective Detection of Ni2+ Ions.

The presence of an abnormal amount of Ni2+ in the human body causes various health issues. Therefore, this work aimed to synthesize the curcumin-based fluorescence-on sensor P [2,6-bis((E)-4-chlorobenzylidene)-cyclohexan-1-one] that was capable of selectively responding to Ni2+ ions in aqueous solution. The structure of P was confirmed by 1H NMR and Fourier transform infrared (FTIR) spectroscopy. The Ni2+ ion sensing was based on the fluorescence enhancement of the fluorophore (P) in neutral aqueous medium. The response of the P-based sensor was highly selective toward Ni2+ ions, whereas the possible interferences from other metal cations were negligible. P had a fast response; it was selective and had a sensitive detection limit (LOD = 2 × 10-10 M) toward Ni2+ ions in neutral medium with a high association constant (K) value of 3.6 × 105 M-2 for the complex formation between the P and Ni2+ ions. Job's plot and DFT calculations proved that the binding stoichiometry of P for Ni2+ was 2:1. P was recovered using EDTA as a chelating agent after being employed as a fluorescent sensor. These characteristics ensured the potential use of P as a new class of chemosensor for environmental applications.

A naphthalenecarboxamide based fluorescent sensor for selective detection of Fe3+ and CN‾: Live cell imaging and INHIBIT logic gate operation

A new fluorescent chemosensor, N,N'-bis(1-hydroxynaphthalene-2-carboxamide)-2-aminobenzylamine (H4L) has been synthesized by a green ionic liquid-based method using tetrabutylammuniom bromide (TBAB) as an environmentally benign reaction medium, and utilized for detection of Fe3+ and CN‾ ions in DMSO-H2O (8:2 v/v) solution. The selective fluorescence response of this chemosensor to Fe3+ is excellent with a fluorescent detection limit (LOD) of 5.16 × 10-7 M. The Job’s plot and ESI-MS analysis indicated a stoichiometric binding ratio of 1:1 between the tri-anionic form of the chemosensor, HL3-, and Fe3+. H4L also displays rapid fluorescence “Turn-On” response to cyanide anion with high selectivity and sensitivity. The detection limit for CN‾ in solution is 2.65 × 10-7 M. Thiscell-permeable probe has also been utilized toimageintracellular Fe3+and CN‾ ions inHeLa cells. Furthermore, the “off–on-off” fluorescence behavior of H4L at 433 nm has been utilized in the fabrication of “INHIBIT” logic gate with Fe3+ and CN‾ as chemical inputs and fluorescence (I433 nm) as output.

Hydrobenzoic acid-based ‘Turn-Off’ fluorescent sensor for selective detection of Cu2+ ions: Chemical preparation, characterization and photophysical studies

Present work describes the preparation of an imine-based fluorescent on–off sensor probe, 2-(3-ethoxy-4-hydroxybenzylideneamino)-5-hydroxybenzoic acid (EHBA) and characterized by using UV–Visible, ESI-MS, 1H NMR, 13C NMR and FTIR spectral techniques. The binding mode ratio between the chemosensor (EHBA) with Cu2+ metal ions in 1:1 stoichiometric ratio respectively. The synthesized probe demonstrated sensitive and selective detection capability towards Cu2+ ions. Further, the sensor EHBA showed visually change in color in the presence of Cu2+ ions, the solution appeared yellow in color was observed. Besides, the sensor EHBA exhibited an outstanding sensitivity and selectivity exceptionally for Cu2+, while the other remaining various metal ions (Zn2+, Pb2+, Hg2+, Mn2+, Ni2+, Co2+, Fe2+, Cd2+, Cr3+, Al3+, Na+, K+ and Ag+) were remain unchanged. Moreover, a remarkable quenching in the fluorescence intensity was exhibited by the sensor probe EHBA with the addition of Cu2+ ions. It is worth to note that the limit of detection for Cu2+ was found to be 0.39 µM respectively.

Magnetic molecularly imprinted polymers as a fluorescent sensor for selective detection of Sudan I in chili powder.

In this manuscript, a novel strategy to design and prepare magnetic molecularly imprinted polymers (MMIPs) is proposed. Based on the synthesized MMIPs, a fluorescent sensor for low-cost and fast detection of Sudan I was established. Under the optimal conditions, the fluorescence intensity of MMIPs decreased linearly with the concentration of Sudan I in the range of 1-40 μM, and the detection limit was 0.38 μM. The present fluorescent sensor demonstrated satisfactory performance for the quantification of Sudan I in chili powder, covering a concentration range of 49.66-993.12 mg kg-1. The LOD was determined to be 17.38 mg kg-1. Furthermore, the average percentage recovery for both intraday and inter-day precision studies ranged from 98% to 104% and 99% to 105%, respectively. The experimental results indicate that the prepared MMIPs exhibited broad potential for low-cost and fast detection in food safety analysis.

Dansyl-triazole-based fluorescent macrocycle for selective detection of nitro-antibiotic drugs and protein interaction.

A novel dansyl-triazole-based fluorescent macrocycle with high Stokes shift and positive solvatochromism was developed. This is an excellent fluorescence sensor for selective detection of nitro-containing antibiotics and other nitro-heteroaromatics. Detection was possible in real samples/paper strips in submicromolar concentration. The interaction of the macrocycle with multiple proteins exhibited its bioactivity.

A highly selective supramolecular fluorescent probe for detection of Au3+ based on supramolecular complex of pillar[5]arene with 3, 3′-dihydroxybenzidine

This study describes a highly sensitive and selective fluorescence sensor for detection of Au3+ ions. It uses a 3, 3-dihydroxybenzidine/phosphate pillar[5]arene inclusion complex (DHB/PP5A IC) in a pure water phase. The host-guest IC of DHB and PP5A was prepared using the saturated solution method, which greatly improved the water solubility of DHB. The inclusion behavior and stoichiometric ratio of DHB and PP5A were investigated using the spectroscopic titration method. The IC was further characterized by 1H NMR, 2D NOESY, SEM, FT-IR, and XRD methods. The theoretical calculation identified the most stable inclusion mode of the DHB/PP5A IC. Fluorescence spectroscopy studies showed that the DHB/PP5A IC has a rapid, highly sensitive, and selective fluorescence quenching effect on Au3+ ions in pure water, with a detection limit of 6.9 × 10−8 M. The IC has the advantages of strong interference resistance and good adaptability across a wide range of pH values. The IC reported in this study provides a new approach to the detection of Au3+ ions in the fields of environmental and biomedical analysis.

Selective turn-on fluorescence sensing of Fe2+ in real water samples by chalcones

The design of fluorescence sensor for selective detection of Fe2+ is very important as it is part of different biochemical redox system related to a number of diseases. In many occasion sensors are unable to distinguish Fe2+ from Fe3+ ions. In the present work, we report simple chalcone type sensors for sensing Fe2+ ions in semi aqueous system. The receptors R1 and R2 have showed excellent sensing properties at pH 7 in CH3OH-H2O (1:1, v/v) solvent system. The fluorescence emission intensity of the complexes between hosts and Fe2+ is least affected by the other competitive metal ions leading to the formation of very tight host–guest complex. The LOD for the R1 and R2 for Fe2+ are 1.91 μM and 3.54 μM respectively, which is quite low in compared to the many other reported sensors. The practical applicability of these sensors is determined by the detection of Fe2+ in real water samples. So chalcones would be cost effective PET inhibited fluorescence sensor for Fe2+.

A novel colorimetric and “turn-on” fluorescent sensor for selective detection of Cu2+

In this work, a new highly selective and sensitive fluorescent sensor for detecting Cu2+ was developed based on rhodamine fluorophore. It displayed strong fluorescence “turn-on” effect upon addition of Cu2+, and possessed the function of naked eye recognition. The fluorescence enhancement also enabled the sensor to quantitatively analyze Cu2+ due to the formation of a stable 1:1 metal–ligand complex in a short time, and the complex possesses relatively good pH stability. In addition, the density functional theory calculations were adopted to investigate the molecular orbitals as well as the spatial structure. Simultaneously, the cell imaging and zebra fish experiments provided a broader application prospect in biological system.

Co2+ and nitrobenzene sensing using indium-based metal-organic framework

A highly stable indium-based metal-organic framework, namely [In(HTCA)(OH)]·2DMF·H2O (JOU-24), was solvothermally synthesized by using fluorescent ligand H3TCA (H3TCA = 4,4′,4″-tricarboxytriphenylamine). Single-crystal X-ray diffraction analyses show that JOU-24 displays two-dimensional framework based on infinite straight In-O-In chains. Further studies show that JOU-24 can keep its stability in water with pH range from 1 to 11. Thereafter, JOU-24 was developed as an excellent fluorescence sensor for selective detection of Co2+ and nitrobenzene (NB) in water due to its good fluorescence performance. For Co2+ sensing, a high quenching content is determined to be 24,500 with a low determine limit of 4.9 × 10−6 mol/L. For NB sensing, quenching content is 10230, which is also comparable to other reported MOFs. In addition, the mechanism for Co2+ and NB sensing is also proposed. This work shows a simple method to construct high-efficient fluorescence sensor for metal ions and nitroaromatics detection.

Construction of an ultra-small hydrazone-linked covalent organic polymer for selective fluorescent detection of ferric ion in aqueous solution

A novel ultra-small hydrazone-linked covalent organic polymer (UHCOP) was synthesized based on the Schiff-base reaction between 2,4,6-trihydroxy-1,3,5-benzenetricarbaldehyde and 1,4-benzenedicarbohydrazide at room temperature and utilized as a sensitive fluorescent sensor for rapid (<2 min) and selective detection of Fe3+ in aqueous solution. The prepared UHCOP displayed ultra-small size with the diameter of 7.98 ± 0.97 nm and gave a stable fluorescent emission at 510 nm. UHCOP exhibited good sensitivity and highly selectivity towards Fe3+. The coordination interaction between UHCOP and Fe3+ resulted in the obviously aggregation-caused quenching response of UHCOP. The linear range was from 5.0 μM to 1.4 mM (R2 = 0.999) with the detection limit of 2.5 μM. Finally, UHCOP has been successfully applied in the detection of Fe3+ in real water samples, proving the fabricated UHCOP is promising as a sensitive fluorescent sensor for selective detection of Fe3+ in aqueous solution.

Study of A Tridentate Schiff-Base as A Highly Selective Fluorescent Sensor for Detection of Copper and Chromium Ions

A simple and easily synthesized fluorescent sensor, Schiff base sensor (SBS), produced by condensation reaction of equal amounts of anthranilic acid and salicyladehyde. It was synthesized and characterized systemically. Both UV-vis and fluorescence spectroscopic studies indicated that the SBS sensor showed good selectivity toward the studied ions: Na+, K+, Cu2+, Co2+, Fe3+ , Al3+ and Cr3+. Whereas, chromium (III) and copper (II) exhibited the largest fluorescence enhancement over the other investigated ions. Chelation-enhanced fluorescence were shown upon the interaction of SBS sensor with some metal ions studied forming inclusion complexes. The fluorescent sensor in aqueous ethanolic solution exhibited high selectivity towards Cu2+ and Cr3+ ions, forming 2 : 1 (L : M) complex as determined by Job’s plot. The formation constants of the inclusion complexes (Mn+/SBS) were measured via spectrofluorometric method applying Benesi-Hildebrand equation.

Pyridine derived organosilatranes and their silica nanoparticles as “Turn-on” fluorescence sensor for selective detection of Zn2+ ions and their cytotoxicity evaluation

Herein, we describe the synthesis of Schiff base derived organosilatranes having pyridine moiety in the scaffold by using the simple synthetic method. The structure of the newly synthesized heterocyclic compounds was deduced by using various spectroscopic studies. The Chemosensor demonstrated the high selectivity and sensitivity for Zn2+ ions by displaying a significant change in UV–vis and fluorometric spectroscopy spectra. The organosilatrane 3a was then immobilized on a silica nanoparticles surface, and the resulting nanohybrids were confirmed using a variety of analytical methods, including TGA, XRD, SEM, and EDX. The hybrid nanoparticles possess higher capacity to bind Zn2+ ions and low limit of detection in comparison to the organosilatranes. The usage of manufactured ligand in real water samples with a percentage recovery of >95% has widened the possibilities for using such a sensor in water treatment applications. Further, to provide valuable information about the ligand interaction with Zn2+ metal ions the complex was synthesized and characterized by 1H NMR spectroscopy, in addition DFT calculations were also performed. Also, the synthesized organosilatranes were tested for their use in the biological field by evaluating their pharmacokinetic profile and cytotoxicity using PreADMET, molinspiration software and SAF-1 cell line.

A chromone-based colorimetric fluorescence sensor for selective detection of Cu2+ions, and its application for in-situ imaging

A chromone-based chemosensor Probe 1 was synthesized, and characterized by FTIR, UV-vis, 1H NMR, 13C NMR, and mass spectrometric studies. Probe 1 exhibited high selectivity and sensitivity for the Cu2+ions over various metal ions (Al3+, Cr3+, Co2+, Cd2+, Mn2+, Fe3+, Ni2+, Zn2+) that was investigated by colorimetric, absorption, and fluorescence titrations. The binding mode of Probe 1 with the Cu2+ ion was derived from Job's plot measurements, and it showed 2:1 stoichiometry. Probe 1 revealed an association constant value of 8.48 × 108 M−2 as determined by employing non-linear least square fit data. The detection limit of Probe 1 for the Cu2+ion was found to be 0.273 × 10−6 mol L−1. Furthermore, Probe 1 was implemented to detect Cu2+ ions in different tissues of the liver fluke, infected and non-infected bovine liver. DFT studies were performed to support the sensing mechanism. The results of these experiments demonstrate that Probe 1 could be a promising chemosensor for the instant naked eye and fluorescence detection of Cu2+ ions in different biological samples.

A Naphthalenecarboxamide Based Fluorescent Sensor for Selective Detection of Fe3+ and Cn‾: Live Cell Imaging and Inhibit Logic Gate Operation

A Naphthalenecarboxamide Based Fluorescent Sensor for Selective Detection of Fe3+ and Cn‾: Live Cell Imaging and Inhibit Logic Gate Operation

Porphyrin-infiltrated SiO2 inverse opal photonic crystal as fluorescence sensor for selective detection of trace mercury ion

Sensing of heavy metal irons in aqueous medium is essential because the presence of heavy metals is very hazardous for environmental safety and human health. Here, a porphyrin-infiltrated inverse opal photonic crystal of silica (TPP-SiO2 IOPC) as the solid optical sensor has been prepared for the selective detection of mercury iron (Hg2+) in aqueous medium, while porphyrin is served as a fluorescence probe and the photonic crystal (PC) provides support as the backbone with special optical property. The intensity of fluorescence during the detection of Hg2+ on the TPP-SiO2 IOPC sensor is 38.9 times larger than that of control sample. The sensor has good linear response to the concentration of Hg2+ from 1.0 × 10−8 to 1.5 × 10−6 mol/L and the lower detection limit observed for Hg2+ concentration is 1.18 nM. Furthermore, the sensor exhibits excellent selection for Hg2+ rather than other metal ions. Therefore, the TPP-SiO2 IOPC sensor can be utilized for fast and simple monitoring of Hg2+.

Novel rapid “turn on” tetrahydro-[5]helicene-based fluorescence sensor for selective detection of Cd2+ with a remarkable large Stokes shift and its applications in food samples and living cell

A new tetrahydro-[5]helicene-based fluorescence sensor (PM) was conveniently synthesized for rapid detection of cadmium ion (Cd2+). PM, which has a tetrahydro-[5]helicene derivative, provided a highly sensitive “turn on” fluorescence sensing recognition for Cd2+, with a remarkable large Stokes shift of 163 nm (1.01 eV). The sensor exhibited a fluorescence enhancement toward Cd2+ via photo-induced electron transfer (PET) quenching, a process related to Cd2+-sensor complexation. PM permitted a high selective response to Cd2+ over other interfering metal ions, such as Zn2+. The application of sensor for detection of Cd2+ in commercial food products, including drinking water and rice, were performed and acceptable results were obtained. In addition, this fluorescence sensor could be efficiently applied as a fluorogenic label for tracking Cd2+ in living cells. The potential Cd2+ determination of PM ensures that this sensor can be utilized as fluorescence materials or devices for the real-time monitoring and control of Cd2+ contamination outbreak.