Selective Optical Sensor Research Articles

A novel sensor for the selective monitoring of trace ytterbium ions using an agarose-based optical membrane.

A novel highly selective sensitive optical sensor was prepared via the chemical immobilization of β-2-hydroxybenzyl-5-bromo-2-hydroxyazastyrene (HBBHAS) on an epoxy-activated agarose membrane pieces. The absorbance variation of the immobilized azastyrene film on agarose upon the addition of 1.5 × 10−5 M aqueous solutions of La3+, Y3+, Al3+, Sc3+, Sm3+, Eu3+, Lu3+, Fe3+, Ce3+, Cr3+, S2O32−, Tb3+, Mn2+ and KIO3 revealed substantially higher changes for the Yb3+ ion compared to the other considered ions. Thus, using HBBHAS as an appropriate ionophore, a selective optical sensor for Yb3+ was prepared via its chemical immobilization on a transparent agarose membrane. The effects of pH, reagent concentration, and time duration of the reaction of immobilizing the reagent were examined. A distinct change in the maximum absorbance of the reagent was established on contact of the sensing membrane with Yb3+ ions at pH = 4.25. For the membrane sensor, a linear relationship was observed between the variation in membrane absorbance (ΔA) at 424 nm and Yb3+ concentrations in the range of 4.75 × 10−5 to 6.20 × 10−10 M with a detection limit of 1.9 × 10−10 M for Yb3+. The effects of some potentially interfering ions on the assessment of Yb3+ were analyzed, and no substantial interference was found. The sensor showed a short response time and decent durability with no reagent leaching. The recovery of Yb3+ ions from the sensor material was performed using 0.3 M HNO3 and its response was reversible and reproducible with RSD ≥ 1.95%. This study reports a non-toxic, economical, stable, accurate, easy-to-use, and novel optical sensor material to assess Yb3+ in synthetic and environmental water samples.

Spectral optical properties of ceramic nanoporous membranes based on anodic aluminium oxide coated silver in ammonia vapors

Spectral optical properties of synthesized ceramic nanoporous membranes based on anodic aluminum oxide coated silver in saturated ammonia gas flow have been experimentally investigated. Based on the measured transmission spectra and detected interference part of the spectra in wavelength range from 550 to 900 nm, temporal and spectral dependencies of the effective optical thickness and its changes in non-equilibrium conditions were obtained due to adsorption of ammonia molecules on silver film surface. According to detected and measured interference maximum shifts up to 14 nm in transmission spectra of Al2O3 + Ag membranes in ammonia gas flow, the possibility of constructing a selective interferometric optical sensors with 10-15 min response time is shown. Keywords: porous anodic aluminium oxide, membrane, silver film, light interference, ammonia vapors, effective optical thickness, interference maximum shift.

Спектральные оптические свойства керамических нанопористых мембран на основе анодного оксида алюминия и покрытия из серебра в парах аммиака

Spectral optical properties of synthesized ceramic nanoporous membranes based on anodic aluminum oxide coated silver in saturated ammonia gas flow have been experimentally investigated. Based on the measured transmission spectra and detected interference part of the spectra in wavelength range from 550 to 900 nm, temporal and spectral dependencies of the effective optical thickness and its changes in non-equilibrium conditions were obtained due to adsorption of ammonia molecules on silver film surface. According to detected and measured interference maximum shifts up to 14 nm in transmission spectra of Al2O3 + Ag membranes in ammonia gas flow, the possibility of constructing a selective interferometric optical sensors with 10 − 15 min response time is shown.

Utilization of a plasticized PVC optical sensor for the selective and efficient detection of cobalt(ii) in environmental samples.

A novel sensitive, selective, and reversible cobalt(ii) ion optical sensor was prepared by the incorporation of 5-[o-carboxyphenylazo]2,4-dihydroxybenzoic acid [CPDB] and sodium tetraphenylborate (NaTPB) in a plasticized polyvinyl chloride (PVC) membrane containing dioctyl adipate (DOA) as a plasticizer. The influence of several parameters such as pH, base matrix, solvent mediator and reagent concentration was optimized. A comparison of the obtained results with those of previously reported sensors revealed that the proposed method, in addition to being fast and simple, provided a good linear range (0.05–45.20 μM) and low detection limit (0.015 μM). Low detection and quantification limits and excellent selectivity in the presence of interfering ions such as Fe3+, Cu2+, Ni2+, Ag+, Au3+, Cr3+, Cd2+, Zn2+, Hg2+, and SO42− make it feasible to monitor Co2+ ion content accurately and repeatedly in environmental samples with complicated matrices. The optode was regenerated successfully using 0.3 M nitric acid (HNO3) solution while its response was reversible with a relative standard deviation (RSD) lower than 1.9% for seven replicate determinations of 20 μM Co2+ in various membranes. The optode was stable and was stored for at least 15 days without observing any change in its sensitivity.

Wearable Eu@HOF luminescent fabric as a highly selective and sensitive optical synapse sensor for identification of six laboratory volatile compounds by neuromorphic computing

An artificial optical synapse sensor that integrates the Eu@IsoMe fabric based optical sensor and artificial synaptic system was constructed for the sensing of six laboratory volatile compounds.

A novel optical sensor for Pb2+ detection based on in-situ formation of Ruddlesden-Popper phase (C4H9NH3)2PbBr4 perovskite

On account of the concentration sensitive photoluminescence (PL) property of the lead-based Ruddlesden-Popper (RP) phase perovskite material, a novel sensing mechanism for highly selective Pb2+ detection based on the in-situ formation of highly emissive luminescence structure matrix (C4H9NH3)2PbBr4 has been demonstrated. The sensor exhibits high sensitivity and selectivity for detecting Pb2+ in complex metal cations mixture solution. This research reports a novel type of sensor mechanism based on the in-situ formation of luminescent lead-based RP phase perovskite. It paves the way for developing highly selective optical sensors for detecting heavy metal cations via their corresponding luminescence structure matrix.

A highly selective optical sensor for the detection of cyanide ions in aqueous solution and living cells

A fluorogenic naphthalene based receptor (NFS) has been successfully generated by preparation from 3-amino-2-naphthol and 2-hydroxy-1-naphthaldehyde, it was then characterized. Optical and colorimetric properties of the receptor (NFS) in terms of cyanide (CN-) ions were investigated by several methods including naked-eye detection, UV–vis spectrophotometry and fluorescence spectroscopy. A visual color change from yellow to orangish-pink was observed upon interaction of the receptor with cyanide (CN-) ions in solution, while no color change appeared upon addition of the other anions tested. The detection limit of NFS was calculated as 0.21 µM without any interaction with other anions tested which is lower than that described by the World Health Organization for CN– ions in drinking water. It can be concluded that the receptor (NFS) was sensitive and rapid enough for the detection of CN- ions in solutions. The interaction between the receptor and CN– ions was also investigated by 1H NMR titration, MALDI-Tof mass spectrometry, and FTIR-AR spectroscopy. NFS was also applied to the bio-imaging of human epithelial cell line (HEK 293) and the cell imaging studies demonstrated that the receptor was capable of detecting cyanide ions in living cells.

Fluorescein Hydrazide-Appended Metal-Organic Framework as a Chromogenic and Fluorogenic Chemosensor for Mercury Ions.

In this work, we prepared a fluorescein hydrazide-appended Ni(MOF) (Metal–Organic Framework) [Ni3(BTC)2(H2O)3]·(DMF)3(H2O)3 composite, FH@Ni(MOF). This composite was well-characterized by PXRD (powder X-ray diffraction), FT-IR (Fourier transform infrared spectroscopy), N2 adsorption isotherm, TGA (thermogravimetric analysis), XPS (X-ray photoelectron spectroscopy), and FESEM (field emission scanning electron microscopy). This composite was then tested with different heavy metals and was found to act as a highly selective and sensitive optical sensor for the Hg2+ ion. It was found that the aqueous emulsion of this composite produces a new peak in absorption at 583 nm, with a chromogenic change to a pink color visible to the naked eye upon binding with Hg2+ ions. In emission, it enhances fluorescence with a fluorogenic change to green fluorescence upon complexation with the Hg2+ ion. The binding constant was found to be 9.4 × 105 M−1, with a detection limit of 0.02 μM or 5 ppb. This sensor was also found to be reversible and could be used for seven consecutive cycles. It was also tested for Hg2+ ion detection in practical water samples from ground water, tap water, and drinking water.

Calcium selective optical sensor based on calmodulin functionalized porous silicon

Calcium selective optical sensor based on calmodulin functionalized porous silicon

Anthracene based selective Co (II) colorimetric and fluorescent sensor for cytotoxicity studies and real sample analysis

A novel and highly selective fluorescent optical sensor developed from 9-anthracene carboxaldehyde and 2-amino 5-nitro benzophenone (BPAI) was designed and synthesized by ultrasonication for rapid Co2+ detection in ethanol medium by charge transfer and CHEF (Chelation Enhanced Fluorescence) mechanism. The stoichiometry of the complexation was calculated as 1:1 via Job's plot and confirmed by mass spectrum. The structure of both the ligand and the metal complex was confirmed by UV, FT-IR, NMR and mass spectral studies. The mechanism of sensing was observed through experimental calculations. Upon treatment of various metal cations such as Cu2+, Ni2+, Zn2+, Cr3+, Mg2+, Hg2+, Fe2+, Fe3+, Cd2+, Pb2+,Al3+, Pd2+, K+, Na+,As3+ no noticeable changes were observed in both absorbance and fluorescence spectral measurements except that of Co2+. The absorbance of BPAI + Co2+ exhibited two new peaks at 616 nm and 679 nm. The fluorescence response of BPAI at 580 nm was abruptly increased, accompanied by the colour change of the BPAI with Co2+ compared to BPAI. The color change from pale brown to yellow occurred due to the binding of Co2+ with that of BPAI thereby yielding a fluorescence-enhanced product. BPAI exhibited significant selectivity within short response time and strong charge transfer mechanism due to the chelation process. The detection limit was found to be 0.00091 μM which is much lower than the permissible limit recommended by WHO. Real sample analysis was performed for the practical applicability of BPAI in the environment. Furthermore, BPAI can be used as a colorimetric and fluorescent sensor to detect Co2+ in biological environments, demonstrating its low cytotoxicity using MTT assay by MG63 cells and L929 cells.

An agarose based optical membrane sensor for selective monitoring of trace nickel ions

In this paper, a new highly selective optical sensor was prepared by epoxy activation of agarose membrane pieces and chemical immobilization of 1-p-tolyl-3-(3-(trifluoromethyl)phenyl)triaz-1-ene 1-oxide on it. The absorbance variation of immobilized triazene derivative on agarose as a film upon the addition of 1.5 × 10−5 mol L-1 aqueous solutions of Zn2+, Tl+, Al3+, Ca2+, Co2+, CrO42-, Ni2+, Cu2+, H3BO3, Mg2+, Na+, Pb2+, S2O32-, Sn2+, Mn2+, Ce3+, Ag+, Ba2+, Cd2+, Cr3+, Fe3+ and KIO3 revealed substantiality higher changes for the Ni2+ ion compared to other considered ions. Thus, using a triazene derivative as an appropriate ionophore, a selective optical sensor for Ni2+ was prepared by its chemical immobilization on a transparent agarose membrane. The concentration effects of the reagent, pH, and time duration of reaction in immobilizing the ligand were investigated. A distinct change for the absorbance maximum of the ligand was found via contact between the sensing membrane with Ni2+ions at pH = 5.75. For the membrane sensor, a linear relationship was observed between the variance in membrane absorbance (ΔA) at 332 nm and Ni2+ concentrations in a range from 6.28 × 10−5 to 2.80 × 10-10 mol L-1 with a detection limit (3σ) of 1 × 10-10 mol L-1 for Ni2+. The effects of some potentially interfering ions on determining Ni2+ were investigated and no considerable interference was found. The sensor indicated a short response time and decent durability with no reagent leaching trace. The sensor was effectively regenerated by an EDTA solution, and its response was reversible and reproducible with R.S.D. less than 1.7 %. This optode was used to determine Ni2+ in synthetic and environmental water samples.

Nano-scale selective and sensitive optical sensor for metronidazole based on fluorescence quenching: 1H-Phenanthro[9,10-d]imidazolyl-calix[4]arene fluorescent probe

It is crucial to determine and control the metronidazole (MET) ingredient in food and pharmaceuticals for human health and food safety. Even though many sensors have been previously reported to detect MET, there is still a need for a highly selective and sensitive, easy, fast, cost-effective sensor in this area. Herein, we report a fluorescent calix[4]arene derivative (PIMC) for highly selective and sensitive and facile and rapid MET detection based on fluorescence (FL) quenching. The highest FL quenching occurs when PIMC is exposed to MET solution at 400 nm (λex = 340). Owing to the quenching efficacy of MET linearly up to 5.5 × 104 nM was obtained a detection limit of 2.44 nM. Besides, interferences of other pharmaceuticals and ions on probe performance were investigated. The FL probe was successful in MET detection without the assistance of any separation techniques in a pharmaceutical sample (tablet) with an acceptable recovery of 101.3%. The applicability of the current probe as a paper-based sensor to MET detection has been successfully tested. As a result, the proposed probe presents a fast and suitable strategy to sensitive and selective detect MET and proves a good potential for practical applications, especially pharmaceutical preparations.

Lipophilic Fluorescent Dye Liquids: Förster Resonance Energy Transfer-Based Fluorescence Amplification for Ion Selective Optical Sensors Based on a Solvent Polymeric Membrane.

Optical sensors based on solvent polymeric membranes have the potential to measure analytes present in an aqueous solution through the development of a tailored method for a specific target. However, limits in the concentrations of the component dyes have prevented improvements in sensitivity. We propose a Förster resonance energy transfer (FRET)-based fluorescence amplification system for ion-selective optical sensors using a highly fluorescent liquid material composed of a lipophilic phosphonium cation and a pyrene modifying sulfonate anion ([P66614][HP-SO3]), as both the plasticizer and donor, in addition to a combination of the lipophilic phosphonium cation and the fluorescein dodecyl ester anion ([P66614][12-FL]) as the fluorescent sensing dye acceptor. For ion extraction-based sensing, the donor and acceptor were retained in the plasticized PVC membrane with negligible leaching upon exposure to acidic and basic aqueous solutions. Systematic investigation of the donor and acceptor ratios clarified the effect of the amplification factor and the sensitivity of the sensor. At an acceptor doping level of 0.5 mol % (vs donor), an approximately 22-fold higher sensitivity was obtained compared to that of a conventional PVC membrane optical sensor. During ion measurement based on the coextraction of protons and anions, selectivity following the Hofmeister order was observed, which was controlled by the addition of ionophores. The proposed FRET system based on a lipophilic fluorescent liquid material has the potential to significantly improve the sensitivities of optical sensors using solvent polymeric membranes with high selectivities for various target analytes.

Development of a selective and highly sensitive optical chemical sensor for determination of sulfaguanidine based on a novel mixed isopolymolybdates

We report a novel sensitive and selective optical sensor based on [Eu (dmso)8] [Eu (η2NO3)2(dmso)4(α-Mo8O26)0.5] [Mo6O19] (1) for sulfaguanidine (Sg) determination in environmental water. The complex formation processes between Sg and 1 were studied spectrophotometrically, showing that the stoichiometric ratio was determined as 1:1. The sensing thin film was constructed by spin coating of 1 onto glass plate surface. The proposed membrane shows a significant absorbance signal change on exposure to buffer solution of pH 7 containing Sg. The optode surface topology reveals agglomerations after the Sg detection process proving Sg recognition by the thin film. It displays a calibration response for Sg over a wide concentration range of 10−11 M to 10−5 M with a detection limit (LOD) of 6.3 × 10−13 M and response time of 8 min. This optode exhibits good selectivity toward sulfaguanidine (Sg) in comparison with sulfamethoxazole (SMX), Cloxacillin (Clox), l-cystine (L-cys), tryptophan (tryp), NO3−, and Cl−. The proposed absorbance sensor in this work was found to be stable, has good repeatability, reproducibility and an accepted lifetime. Finally, this optode has been applied for Sg determination in mineral and tap water sample finding encouraged results.

Highly Selective Optical Sensor Eu (TTA)3 Phen Embedded in Poly Methylmethacrylate for Assessment of Total Prostate Specific Antigen Tumor Marker in Male Serum Suffering Prostate Diseases.

A low-cost, simple, and highly selective method was used for the assessment of total prostate specific antigen (tPSA) in the serum of prostate cancer patients. This method is based on quenching the intensity of luminescence displayed by the optical sensor Eu (TTA)3 phen/poly methylmethacrylate (PMMA) thin membrane or film upon adding different concentrations of tPSA. The luminescent optical sensor was synthesized and characterized through absorption, emission, scanning electron microscopy (SEM), and x-ray diffraction (XRD), and is tailored to present red luminescence at 614 nm upon excitation at 395 nm in water. The fabricated sensor fluorescence intensity is quenched in the presence of tPSA in aqueous media. The fluorescence resonance energy transfer (FRET) is the main mechanism by which the sensor performs. The sensor was successfully utilized to estimate tPSA in the serum of patients suffering prostate cancer in a time and cost effective way. The statistical results of the method were satisfactory with 0.0469 ng mL−1 as a detection limit and 0.99 as a correlation coefficient.

Adsorption of gas molecules of CH4, CO and H2O on the vanadium dioxide monolayer: computational method and model

Inspired by the recent use of two-dimensional nanomaterials as gas sensors, we used density functional theory calculations to study the adsorption of gas molecules (CH4, CO and H2O) on sandwich vanadium dioxide tablets. The results showed that of all these gases, only the CH4 gas molecule was the electron acceptor with significant charge transfer on the VO2 sheet. The adsorption energies of CH4, CO and H2O are −229.5 meV, −239.1 meV and −388.3 meV, respectively. We have also compared the adsorption energy of three different gas molecules on the VO2 surface, our calculation results show that when the three kinds of gases are adsorbed on the VO2 surface, the order of the surface adsorption energy is H2O > CO > CH4. It is also found that after adsorption of CH4, CO and H2O molecules, the electronic properties of VO2 sheet changed obviously. However, due to the strong adsorption of H2O molecule on VO2 sheet, it is difficult to desorption, which hinders its application in gas molecular sensors. The optical properties of VO2 sheet are further calculated. The absorption of CH4, CO and H2O molecules is introduced to red-shift the dielectric function of the thin film, which indicates that the optical properties of the thin film have changed significantly. According to the change of optical properties of VO2 sheet before and after molecular adsorption, VO2 can be used as a highly selective optical gas sensor for CH4, CO and H2O detection. These results provide a new approach for the potential application of VO2 based optical gas sensors.

A Sensitive and Selective Optical Sensor Based on Molecularly Imprinting Technique Using Green Synthesized Carbon Dots for Determination of Trace Amount of Metronidazole

In this study, an optical sensor has been suggested to measure a trace amount of metronidazole (MTZ). In the first step, an eco-friendly method was used to synthesize carbon dots (CDs) using Eucalyptus leaves for the first time. The obtained CDs showed high solubility in water and high fluorescence intensity. In the next step, the CDs was used as a fluorescence probe for the determination of MTZ. This probe was modified with a sensitive MTZ silica, which was sensitized using imprinting technology. The sensitive composite called CDs@MIPs demonstrated a linear range from 0.4 to 10.0 μg L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> with a detection limit to 0.2 μg L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . High sensitivity, excellent selectivity, ease of fabrication, cheapness, and use of an environment-friendly method to synthesize the fluorescence probe are the advantages of this method. The suggested optical sensor with these desirable features is an attractive method to fast determine of MTZ.

Design of a novel optical sensor for determination of trace amounts of tin in food and in environmental samples

ABSTRACT A novel sensitive, selective, and reversible tin(IV) ion optical sensor was prepared depends on the incorporation of amino-4-(3-nitrophenylazo)pyridine-3-ol, (ANPAP) and sodium tetraphenylborate (NaTPB) in a plasticised polyvinyl chloride (PVC) membranes containing dioctylsebacate (DOS) as a plasticiser. The influence of several parameters such as base matrix, pH, solvent mediator and reagent concentration were optimised. Comparison of the obtained results with previously reported methods indicated that the proposed procedure, in addition to fast and simplicity, provided good linear range (0.03–6.43 μmol L−1) and low detection limit (0.008 μmol L−1). Low detection and quantification limits, and excellent selectivity in presence of interfering ions as Cd2+ Zn2+, Hg2+, Fe3+, Cu2+, Ni2+, Ag+, Mn2+, Cr3+ and SO4 2− make it feasible to accurately and repeatedly monitor Sn4+ ions content in environmental samples with complicated matrices. The sensor was regenerated successfully using 0.2 mol L−1 of nitric acid solution while its response was reversible with the relative standard deviation (RSD) lower than 2.1% for seven replicate determinations of 4.0 μmol L−1 of Sn4+ in various membranes. The sensor was stable and stored for at least one month without observing any change in its sensitivity.

Colorimetric aflatoxins immunoassay by using silica nanoparticles decorated with gold nanoparticles.

Nanomaterials-based colorimetric immunoassays showed increasing attention for monitoring different biomarkers because of their unique optical and electrical features. Here, a highly sensitive and selective optical sensor was described for the determination of different aflatoxins (AFs). Mesoporous silica nanoparticles (m-SNPs) with an average particle size of 40nm were prepared by the sol-gel method and then decorated with gold nanoparticles (AuNPs). The Au NPs@m-SiNPs nanocomposite with an average particle size of 66nm was modified with AFs antibodies. The assay includes the following steps: the Au NPs@m-SiNPs nanocomposite was immersed with AFs antibodies, and then the AFs-Ab/Au NPs@m-SiNPs was used as a probe for AFs detection. The interaction between the AFs-Ab/Au NPs@m-SiNPs and the AFs has resulted in a change in its color from pink to violet. Measurements are performed by absorptiometry at a wavelength of 425nm. The immunoassay works in the concentration range from 1ng·mL-1 to 75ng·mL-1 AFB1 and has a limit of detection 0.16ng·mL-1 (at S/N=3). The assay was applied to the determination of AFs in different food samples spiked with AFS. Finally, the assay was used to detect AFs in a real sample, and the LC-MS technique was used to verify the results.

A selective proton transfer optical sensor for copper II based on chelation enhancement quenching effect (CHEQ)

A novel selective fluorescent sensor for Cu2+ in solution has been developed by means of chelation enhancement quenching effect (CHEQ). The compound N,N′-bis(salycilidene)-(2-(3′,4′-diaminophenyl)benzothiazole (BTS) is reactive to intramolecular proton transfer on the electronic excited state (ESIPT) presenting fluorescence emission in the blue region with very large Stokes shift (8794 cm−1). Spectroscopic titration experiments indicate that not only the fluorescence quenching but also of the ESIPT reaction allowed naked eye detection as a paper strip-based sensor. This chemosensor showed to be selective to Cu2+ among 13 other cations. The sensor:Cu2+ ratio was determined by both Job and Benesi-Hildebrand plots as 1:2. In addition, the binding between sensor and metal was investigated by 1H NMR, FTIR and HRMS in order to elucidate the formed complex and corroborate the results of BTS:Cu2+ ratio. The binding constant was also found as 3.0 × 1010 mol−2 L2 at 25 °C. The detection and quantification limits were also obtained as 32 ppb and 108 ppb, respectively.