Chemical Sensor For Detection Research Articles

Synthesis of silica inverse opal and evaluation of its potential as an optical chemical sensor for detection of metal salts

In this paper, SiO2 inverse opal photonic crystals, made by the co-assembly of SiO2 and polymethylmethacrylate (PMMA) microspheres, were used to detect 20 different metal salts with a concentration of 0.002 mol/L. Surprisingly, two different behaviors were observed. Some metal salts caused a redshift in photonic bandgap (PBG) while the others led to a PBG’s blueshift. The observed different behaviors of salts are due to their distinct influence on the lattice constant of the inverse structures which was precisely investigated by analyzing the field emission scanning electron microscopy (FESEM) images and ultraviolet–visible (UV–Vis) spectroscopy. It has been revealed that the competition between the hydrophilicity of SiO2 and the hygroscopicity of metal salts led to a shift of PBG toward blue or red. The maximum shift in the PBG range was observed for mercury (II) nitrate salt (19 nm), which indicates a sensitivity of 9.5 nm per concentration unit (mM). Furthermore, the lowest displacement of the PBG was observed for the sodium nitrate salt (5 nm), which represents a sensitivity of 2.5 nm/mM. The lowest and highest values of the detection limit (LOD) for mercury (II) nitrate salt and sodium nitrate salt equal 0.193 mmol/L and 0.887 mmol/L, respectively. In addition, according to the calibration curve, with a regression coefficient of R2 > 0.95, there is a linear relationship between the salt concentration and the displacement of the PBG of the structure. Based on the results illustrating the sensitivity of the synthesized inverse opal to the type and concentration of the salts, inverse opal can be regarded as a promising structure to create a new perspective in the field of chemical sensing.

Recent Trends in Chemical Sensors for Detecting Toxic Materials.

Industrial development has led to the widespread production of toxic materials, including carcinogenic, mutagenic, and toxic chemicals. Even with strict management and control measures, such materials still pose threats to human health. Therefore, convenient chemical sensors are required for toxic chemical monitoring, such as optical, electrochemical, nanomaterial-based, and biological-system-based sensors. Many existing and new chemical sensors have been developed, as well as new methods based on novel technologies for detecting toxic materials. The emergence of material sciences and advanced technologies for fabrication and signal-transducing processes has led to substantial improvements in the sensing elements for target recognition and signal-transducing elements for reporting interactions between targets and sensing elements. Many excellent reviews have effectively summarized the general principles and applications of different types of chemical sensors. Therefore, this review focuses on chemical sensor advancements in terms of the sensing and signal-transducing elements, as well as more recent achievements in chemical sensors for toxic material detection. We also discuss recent trends in biosensors for the detection of toxic materials.

A novel dye-sensitised solar cell based portable sensor for chemical detection

In recent years, chemical sensors have shown the potential to provide rapid, accurate, and on-site quantitative detection of analytes, but current methods often require specialised equipment. In this study, a novel dye-sensitised solar cell (DSSC) based sensor is reported for convenient detection of tert-butylhydroquinone (TBHQ) in drinking water. The sensor consists of a gold nanoparticle (AuNP) solution based unit that responds to the concentration of TBHQ and produces an electrical signal change via an integrated DSSC based transducer component. Through analysing the current signal generated by the DSSC sensor, the quantity of TBHQ in an unknown sample can be achieved. Finite difference time domain (FDTD) simulation has been used to explain the relationship between the particle morphologies and optical properties of AuNPs. This work offers a novel strategy of developing portable sensors without needing any scientific instrument.

Quantitative Raman Cross-Sections and Band Assignments for Fentanyl and Fentanyl Analogs.

Raman cross sections and spectra were measured for five synthetic opioid fentanyl analogs: fentanyl citrate, sufentanil citrate, alfentanil HCl, carfentanil oxalate, and remifentanil HCl. The measurements were performed with excitation wavelengths in the visible (532 nm) and near infrared (785 nm). In addition, density functional theory (DFT) calculations were employed to generate simulated spectra of the compounds and aid in identification of the observed spectral modes. These cross-section measurements and calculations were also used to assess results from a series of measurements of fentanyls cut with other powdered materials. These measurements are valuable for assessment of field-deployable Raman chemical sensors for detection of fentanyl and fentanyl analogs, including when mixed with other materials.

Metal-decorated BN monolayer as potential chemical sensors for detection of purinethol drug

Using the density functionals B3LYP, M06-2X, and B97D, we found that the interaction of boron nitride nano-sheet (BNNS) with purinethol (PT) drug is a physical adsorption with a small sensing response (SR) of 7.9. To increase the sensitivity, we decorated Ni, Pd, Ag, and Au metals on the sheet and then we found that the adsorption energy of PT changed from −4.9 on pristine BNNT to −18.3, −18.8, −19.4, and −19.9 kcal/mol, respectively. The corresponding SR dramatically increased to 41.2, 50.3, 65.1, and 79.3. This shows that the sensitivity of the metal-decorated BNNS ([email protected]) increased by increasing the atomic number of metals. However, we predicted that Au atom increased the sensitivity of BNNS to PT more than other metals. The SR of the metal[email protected] slightly decreased in the water solvent. Finally, based on our theoretical results, the metal-decorated BN nano-structures have further practical applications.

An impedimetric e-tongue based on CeO2-graphene oxide chemical sensors for detection of glyphosate and its potential interferents

• Use of original CeO2/graphene oxide impedimetric sensors. • Impedimetric electronic tongue to detect glyphosate without needing redox reactions. • Sensor method with response identical to quantitative 1H NMR at 95 % confidence level. • Discrimination of glyphosate from aminomethyl phosphonic acid and N -nitroso glyphosate. • -Mechanism of detection ascribed to differences of dipole moment of analytes. Glyphosate (GLY) is the most common and widespread herbicide applied to prevent unwanted weeds. However, its detection with conventional analytical methods is a hard task. In this regard, this contribution proposes an original impedimetric electronic tongue (IET) based upon CeO 2 -graphene oxide chemical sensors and principal component analysis for easier detection of GLY. This IET was capable of detecting GLY within a linear range of concentrations, 110 to 290 nmol/L (R 2 = 0.99), showing a limit of detection of 30 nmol/L, which is far below that established by international safety regulations. This was made possible even in the presence of potential interferents, namely aminomethyl phosphonic acid and N -nitroso glyphosate. The IET performed identically to quantitative 1 H NMR at 95 % confident level. Once it does not rely on redox reactions or previous derivatization, this IET is a simpler alternative to detect and monitor GLY and its interferents in aqueous media.

Ru-decorated gallium nitride nanotubes as chemical sensor for detection of purinethol drug: a density functional theory study

We employed density functional B3LYP to inspect the impact of Ru-decoration on a GaN nanotube (GaNNT) sensing performance in detection of purinethol (PT) drug. The interaction of the pristine GaNNT with the PT was found to be weak, and the sensing response is 4.3. Decorating an Ru atom into the GaNNT surface increases the adsorption energy (Ead) of PT from −6.5 to −23.6 kcal/mol. The sensing response significantly rises to 93.6 by Ru-decoration. A short recovery time of 15.7 s is found for the PT desorption from the Ru-decorated GaNNT surface at 298 K. The water solvent reduces Ead of PT to −20.1 kcal mol−1. Thus, it suggests that Ru-decorated GaNNT may be a highly sensitive PT sensor with a short recovery time.

Determination of Buprenorphine (BUP) with Molecularly Imprinted Polymer Zn/La3+ Metal Organic Framework on Modified Glassy Carbon Electrode (GCE)

AbstractIn this study we report the Zn/La3+ metal organic frameworks (MOFs) were synthesized with the co‐precipitation assisted microwave method. Zn/La3+ MOFs were used as a new nanocomposite for the design and construction of a nanosensor based on glassy carbon electrode (GCE). MOFs due to their unique and excellent physicochemical properties can be used in sensors based on glassy carbon electrode (GCE). The synergistic effect of MOFs on glassy carbon electrode increases the power of the limits of detection (LOD). In this study, a new chemical sensor was fabricated by electro polymerization to measure buprenorphine with MOFs based on molecularly imprinted polymer. Zn/La3+ MOFs nanostructures were identified with scanning electron microscopy (SEM), Dynamic light scattering (DLS), Transmission electron microscopy (TEM) and the Fourier‐transform infrared spectroscopy (FT‐IR) spectra. Buprenorphine was used as a template, pyrrole was used as a monomer, potassium ferrocyanide as an electrochemical active tracer in electropolymerization processes and the parameters affecting the sensor response were optimized. At the Zn/La3+ MOF/MIP electrode, the calibration curve in the linear region was obtained in the concentration range between 4 to 50 ng/ml and the detection limit was 1.08 ng/ml. In a new strategy, Zn/La3+ MOFs nanostructures can be introduced as new materials with high efficiency which used at chemical sensors for detection of the opiates in all over the world.

One-step Bridging of g-C3N4 and Graphene Oxide by Successive Electrolysis for Constructing Electrochemical Sensor of Pb2+

Synthesis methods of composites materials can tailor individual materials properties and make the composite possess more superior performance than individual materials. Herein, by combining –NH 2 group in graphitic carbon nitride (g-C 3 N 4 ) and a facile electrolytic route, g-C 3 N 4 -bridging reduced graphene oxide nanocomposite (g-C 3 N 4 /r-GO) was successfully prepared to construct chemical sensor for detection of Pb 2+ . Because g-C 3 N 4 contains a large amount of –NH 2 group, covalent bonds as bridges between GO and g-C 3 N 4 could be successfully formed by successively electrolyzing, which simultaneously induced removal of electron withdrawing group in r-GO. Such bridges could shorten the planar distance between GO and g-C 3 N 4 in comparison with the conventional π-π stacking, improving the electrochemical performance of r-GO and g-C 3 N 4 . Moreover, the above unique chemical structure of g-C 3 N 4 /r-GO not only exhibited excellent electrical conductivity but also provided plenty active sites to chelate Pb 2+ from solution. Therefore, the prepared g-C 3 N 4 /r-GO ensured chemical sensor for Pb 2+ detection with wide linear range (1.0–300 μg/L) and low detection limit (0.15 μg/L at S / N = 3). This simple method could also be extended to preparation of other elements-contained nanomaterials functionalized oxide graphene for improve its properties and widen its potential applications. Covalent bonds as bridges between GO and g-C 3 N 4 was successfully formed by successively electrolyzing which simultaneously induce removal of electron withdrawing group in GO. Such bridges can shorten the planar distance between r-GO and g-C 3 N 4 in comparison with the conventional π-π stacking, improving the electrochemical performance of the r-GO and g-C 3 N 4 . The prepared g-C 3 N 4 /r-GO not only exhibited excellent the electrical conductivity but also provided plenty active sites to chelate Pb 2+ from solution.

Chemical Sensor for Detection of Lead Levels in Herbal Medicine

A new tube type Pb2+ sensor made from two types of mixtures, namely clay-PbI2 and chitosan-PbI2 were prepared. An electromotive force (EMF) with Ag/AgCl as the reference electrode was used as the output signal. The highest performance of the Pb2+ sensor from clay-PbI2 was obtained at Pb2+ solutions in HNO3 and pH 3 with sensor sensitivity of 20.67 mV/decade. The highest performance of the Pb2+ sensor from chitosan-PbI2 was obtained at Pb2+ solutions in demineralized water with sensor sensitivity of 32.49 mV / decade. Application of the two sensors on several commercial herbal samples resulted in an average recovery of 85.62% and 94.10% for sensor from chitosan-PbI2 and clay-PbI2, respectively

A Novel Calix[4]arene Thiourea Decorated with 2‐(2‐Aminophenyl)benzothiazole Moiety as Highly Selective Chemical Gas Sensor for Dichloromethane Vapor

AbstractA newly synthesized calix[4]arene thiourea derivative decorated with 2‐(2‐aminophenyl)benzothiazole unit is selected to take part important role in host‐guest interactions of the macrocyclic molecules. p‐tert‐butylcalix[4]arene dithiourea (C[4]‐DT) Langmuir‐Blodgett (LB) thin films are prepared and characterized to develop a new sensing element for the detection of seven different organic vapors (dichloromethane, chloroform, acetone, benzene, carbon tetrachloride, toluene and m‐xylene). The preparation of C[4]‐DT‐based thin films onto the different substrates was successfully and uniformly achieved with linear regressions of 0.9971 and 0.9954 for coating onto quartz glass and quartz crystal, respectively. The frequency shift (61.01 Hz) and the mass deposited onto quartz crystal (969.80 ng) were calculated for each layer. The swelling dynamics of C[4]‐DT QCM chemical sensor was also illuminated by developing the early time Fick's diffusion equation. The sensing measurements can be concluded that owing to its high sensitivity (6.63 Hz/ppm), fast response and low detection limit (0.45 ppm), this proposed C[4]‐DT LB coated sensor is expected to be promising alternative chemical sensor for detection of DCM vapor.

Methodology for binary detection analysis of inkjet-printed optical sensors for chemical detection

We have developed inkjet-printed surface-enhanced Raman spectroscopy (SERS) sensors that are specifically designed to work with field portable Raman analyzers for the detection of chemical and biological agents (Tay et al. in J Raman Spectrosc, 2020). These SERS sensors are inkjet-printed on filter paper or fabric substrates. They are flexible and lightweight and provide point-of-sampling capabilities that other rigid planar SERS substrates lack. Conventionally, performance of a SERS substrate is characterized by its enhancement factor which is defined as the ratio of the normalized SERS to normal Raman intensity. This is an inadequate measure for a chemical/biological sensor. The performance of a chemical/biological sensor is best characterized by its sensitivity, probability of true positive detection, false positive rate, and its response time. The sensor using receiver operating characteristic (ROC) captures the performance trade-off between all these factors. Here, we outline the application of ROC analysis to the SERS sensors. This can be applied for all SERS sensors but we will focus its use with the printed SERS sensor. Specifically, the use of printed SERS sensor for the detection of fentanyl, a common opioid found in illicit drug, analyzed with ROC concept is demonstrated.

Three-Dimensional Impedance-Based Sensors for Detection of Chemicals in Aqueous Solutions

In this work, the development of three-dimensional impedance-based biochemical sensors for detection of chemicals and biological agents in aqueous solutions is presented. The sensors are made of a stack of suspended electrodes that allow the solution to occupy the space between them and create a larger interface area between the aqueous solution and the electrodes. Increasing the solution-electrode interface area drastically changes the impedance of the sensor-solution resulting in a better sensitivity.

Three-Dimensional Impedance-Based Sensors for Detection of Chemicals in Aqueous Solutions

Three-Dimensional Impedance-Based Sensors for Detection of Chemicals in Aqueous Solutions

Analysis of Nanomaterials Based on Indium and Zinc Oxides by High Resolution Atomic Absorption Spectrometry with the Use of Continuous Spectral Source and Electrothermal Atomization

The properties of nanostructured materials based on zinc and indium oxides can be modified by adding alloying elements to obtain the necessary electrical or optical properties. For example, the specificity of the chemical properties of ZnO and In2O3 for the determination of toxic gases is achieved by immobilizing Au, Ag, etc., nanoparticles on their surface. Control of the material composition plays an important role in determining the dependence between the dopant content and functional properties of the materials. The study is aimed at the development of a methodical approach to the multielement determination of catalytic dopants (Ag, Au) and matrix elements in nanostructured tin and indium oxides using the method of high resolution atomic absorption spectrometry with electrothermal atomization (ETAAS) and continuous spectral source. The matrix of the synthesized nanostructured materials is the corresponding oxide with possible oxygen deficiency due to the temperature conditions of the synthesis (300–700°C), and the content of additives (Ag, Au) is varied from 1 to 3 wt %. Optimal conditions of pyrolysis and atomization for sequential multielement analysis by the ETAAS method are determined. The optimal pyrolysis temperatures for determining Ag and Au (for both oxides), In, and Zn are 1000, 1600, 1200, and 900°C, respectively. The optimal atomization temperatures for determining Ag and Au (for nanomaterial based on indium oxide), Au (for nanomaterial based on zinc oxide), In, and Zn are 1800, 2200, 2100, 2200, and 1500°C, respectively. The accuracy of analyte determination reaches 1–4% (rel.). The correctness of the results is confirmed by inductively coupled plasma mass spectrometry. The developed method provides control of the composition of synthesized nanostructured materials for their more efficient use in photovoltaics, as well as in production of chemical sensors for detection of harmful compounds like CO, NO2, and NH3.

Four-Channel Monitoring System with Surface Acoustic Wave Sensors for Detection of Chemical Warfare Agents.

Recently, efforts have been made to adapt surface acoustic waves (SAWs) for use in chemical sensors for detection of chemical warfare agents (CWAs). In this study, a four-channel real-time CWA detection system was constructed using four 250-MHz SAW sensors. Each system consists of three different chemical sensors and one reference sensor. The reference sensor compensates for frequency variations according to humidity and temperature conditions. Signals from the SAW sensors can be checked on a PC-based graphical user interface without additional measuring equipment. To measure dimethyl methylphosphonate (DMMP), a simulant of sarin gas, polyhedral oligomeric silsesquioxane (POSS) and thiourea (TU)-based synthetic polymers were used as sensing materials. The reference sensor was not coated, whereas the three different chemical sensors were coated with POSS, TU-1, and TU-2. The maximum frequencies of POSS, TU-1, and TU-2 were shifted 15.86, 13.85, and 0.944 kHz, showing significant values. We also found a relatively good linear relation between the frequency shift and the concentration of DMMP. The three sensing materials selected-POSS, TU-1, and TU-2-responded significantly to DMMP and triethylphosphate in the selectivity tests. This response is due to the chemical bonding of the sensing materials with the phosphonate in the nerve-agent simulants. These results indicate that the four-channel SAW monitoring system described in this paper shows potential as a portable real-time monitoring system to detect a variety of toxic vapors simultaneously, without using complex measuring equipment. In addition, this approach has demonstrated potential for developing excellent portable sensors to detect different types of CWAs.

A novel fluorescence assay based on self-doping biomass carbon dots for rapid detection of dimethoate

A novel approach was proposed to prepare carbon dots (CDs) by acid carbonization and hydrothermal treatment of pork rib bones from food waste. The synthesized animal waste biomass CDs have the merits of eco-friendly, superior fluorescence properties and biocompatibility. The fluorescence of animal waste biomass CDs could be quenched efficiently by dithizone due to the coordination effect. With the addition of dimethoate, the dithizone ligands at CDs are replaced by hydrolysates, and hence the fluorescence is recovered. Thus, a sensing platform was constructed based on the coordination-originated fluorescence of animal waste biomass CDs which can sensitively and selectively detect dimethoate due to a simple displacement mechanism. Upon optimal conditions, the detection limit of dimethoate is 0.064 μM. The linear ranges were obtained in a range of 0.15 μM–5.0 μM. The method is rapid, convenient and environmentally acceptable that can directly detect dimethoate in water samples with recoveries of 93 %–105 %, and the relative standard deviations (RSDs) were 2 %–6 %, respectively. This simple strategy can be used to develop the fluorescence recovery sensors for chemical detection.

Determination of Cr(III) ions based on plasmonic sensing and anodic stripping voltammetry with amplification of Ag nanoparticles

In this paper mercapto succinic acid (MSA) capped gold nanoparticles (AuNPs) upon indium tin oxide (ITO) glass strips (ITO/AuNPs/MSA) have been used as platform for detection of Cr(III) ions. Cr(III) ions can be immobilized on the surface of AuNPs through formation of complex with MSA, allowing the development of plasmonic and electrochemical methods in assays. The plasmonic sensing is based on the formation of complex between ITO/AuNPs/MSA-Cr(III) and BSA as the second complexant, resulting the red-shift of plasmonic AuNP peak due to the change of environmental refractive index. The concentration of Cr(III) ions could be detected in the linear range of 10 nM–1 mM. On the other hand, the electrochemical method is based on the formation of complex between ITO/AuNPs/MSA-Cr(III) and MSA capped silver nanoparticles (MSA/AgNPs), in which Ag can be detected by anodic stripping voltammetry. With the amplification of AgNPs, the sensitivity of the Cr(III) detection was further improved. The stripping current was found to be linearly proportional to the concentration of Cr(III) ions from 0.1 to 10 nM with detection limit of 0.05 nM. The proposed both methods have great potential in the design of chemical sensors for detection of metal ions in field analyses.

Boron nitride nanoclusters as a sensor for Cyclosarin nerve agent: DFT and thermodynamics studies

To find a chemical sensor for detection of Cyclosarin (GF) nerve agent, we studied its interaction with B24N24, AlB23N24, B16N16 and AlB15N16 nanoclusters by means of density functional theory calculations. All calculations were investigated whit the M06 method and 6-311G(d,p) basis set. It was demonstrated that the interaction of GF with AlB23N24 and AlB15N16 is more stable than that of the B24N24 and B16N16. Thermodynamic parameters indicated that the AlB23N24 and AlB15N16 interactions with the GF are exothermic and spontaneous. Despite both AlB23N24 and AlB15N16 demonstrated strong adsorption, the electronic properties calculation indicated that AlB15N16 sensitive to the nerve agent adsorption. Our results predicted AlB15N16 has good potential as a sensor for the detection of GF.

Modification of an Anopheles gambiae odorant binding protein to create an array of chemical sensors for detection of drugs

The binding pockets of odorant binding proteins from Anopheles gambiae (OBP1 and OBP47) were analysed using in silico modelling. The feasibility of creating mutant proteins to achieve a protein array capable of detecting drugs of abuse in solution or in vapour phase was investigated. OBP1 was found to be easily adapted and several mutant proteins were expressed and characterised. AgamOBP1_S82P was found to have high affinities to cannabinol, 3,4-methylenedioxy methamphetamine (MDMA/Ecstasy) and cocaine hydrochloride. When these proteins were immobilised on a quartz crystal microbalance, saturated cocaine hydrochloride vapour could be detected. The sensors were stable over a period of at least 10 months in air. The approach taken allows flexible design of new biosensors based on inherently stable protein scaffolds taking advantage of the tertiary structure of odorant binding proteins.