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Electrical Properties of Porous Silicon for N2 Gas Sensor
摘要： The application of porous silicon (PSi) for gas sensing devices has gained a considerable attention in the last decade. This work considers the electrical features of PSi layers prepared by electrochemical etching. We find that in order to get a better understanding of the absorption properties of PSi surface, it is necessary to know how the PSi morphology depends on the etching parameters. The physical structure of PSi, i.e., porosity, and pore size distribution can be controlled by changing the Hydrofluoric Acid concentration, current density, anodizing length and etching time in anodizing procedure. We describe our test system for gas sensors and investigate on the electrical behavior of PSi layers (p-type) in N2 gas for various fabrication conditions. The results show that the current density increases significantly as N2 gas is adsorbed. The measurements of the I-V characteristics were carried out at atmospheric pressure, room temperature, and with N2 gas as well.
关键词： Current-voltage curve,N2 gas,Porous silicon,Gas sensor
更新于2025-09-23 15:23:52
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Self-electrochemiluminescence of poly[9,9-bis(3‘-(N,N- dimethyl amino)propyl)-2,7-fluorene]-alt- 2,7-(9,9- dioctylfluorene)] and resonance energy transfer to aluminum tris(8-quinolinolate)
摘要： In this paper, the electrochemiluminescence (ECL) behavior of a hole-transport polymer, poly [9,9-bis(3'-(N,N-dimethylamino) propyl)-2,7-fluorene]-alt-2,7-(9,9-dioctylfluorene)] (PFN) was examined with the purpose of finding a novel organic ECL emitter. It was found that the PFN exhibits self-electrochemiluminescence (self-ECL) without any exogenous co-reactants. Quite different from the traditional ECL, the addition of tripropyl amine (TPA) quenched the self-ECL of PFN. PFN ECL intensity reaches a peak during electrochemical oxidation process due to the superposition of self-enhanced ECL, and aggregation quenching of excited state by PFN excimer formation. Aluminum tris(8-quinolinolate) (AlQ3) doped with PFN recovers luminescence intensity with restraining quenching effect via ECL resonance energy transfer from PFN to AlQ3, giving rise to a stable luminescence signal, and hence sensory detection of nitroaromatics. The limits of detections for nitroaromatics can reach down to a level of 10^-22 M. This work sets the stage for a novel organic polymer-based ECL emitter without using any toxic exogenous co-reactant, and presents a practical avenue for a prototype of realising sensory detection through signal stabilization via energy resonance energy transfer (ERET).
关键词： poly[9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene]-alt-2,7-(9,9-dioctylfluorene),Sensor,Resonance energy transfer,Self-electrochemiluminescence
更新于2025-09-23 15:23:52
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Rapid detection of sulfaguanidine in fish by using a photonic crystal molecularly imprinted polymer
摘要： A photonic crystal (PC) sensor was prepared through molecular imprinting by using dispersed SiO2 microspheres as PC, sulfaguanidine (SG) as template, methacrylic acid as monomer, and ethylene glycol dimethacrylate as crosslinker. The preparation conditions were optimized as follows: molar ratio of template, monomer, and crosslinker was 1:10:4; pH was 6.0 in phosphate buffer; and volume fraction of methanol was 15%. The relationship between wavelength shift of reflection peak and SG concentration was found as: △λ=7.8887 lg(C)+79.9664. The response time was only 5 min. The limit of detection was 2.8×10-10 mol L-1. The sensor exhibited higher specificity for SG than its sulfonamide analogs. The sensor maintained original sensing performance after five cycles of usage. The recoveries of SG ranged from 93.8% to 111.2% in lake water and from 88.5% to 115.2% in fish samples. This finding suggested that the sensor can be used in food samples with complicated matrix.
关键词： Sulfaguanidine,Sensor,Photonic crystal,Molecular imprinting
更新于2025-09-23 15:23:52
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Bioinspired Color Changing Molecular Sensor toward Early Fire Detection Based on Transformation of Phthalonitrile to Phthalocyanine
摘要： The fire detection plays a critical role in the maintenance of public security. Previous approaches of early fire warning, based on smoke or temperature response must be set in the proximity of a fire. They cannot provide the additional information of fire location or size and are susceptible to complicated situations. It is still a big challenge to make rapid and accurate early fire warning in precombustion because of the lack of reliable alarm signals. Herein, a precursor molecular sensor (PMS) is designed and synthesized that can present the chemical structure transformation to form phthalocyanines (Pcs) and release a color change signal at about 180 °C, learning from the plant chlorophyll metabolism. Further, the PMS is assembled to an early fire warning component (EWC) and an intelligent image recognition algorithm is introduced for unburned fire detection. The EWC generates a colorful alarm within 20 s at 275 °C. Therefore, the facile PMS provides a reliable real-time monitoring strategy to the early fire warning detection in precombustion.
关键词： color change,molecular sensor,image recognition algorithm,phthalocyanine,early fire detection
更新于2025-09-23 15:23:52
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A Simple Rhodanine-Based Fluorescent Sensor for Mercury and Copper: The recognition of Hg2+ in aqueous solution, and Hg2+/Cu2+ in organic solvent
摘要： Detection of copper and mercury attracts important in most environmental and biological systems. In this study, the simple probe 2-OxI-Rh containing rhodanine core was synthesized by a green approach and sensing properties were studied using colorimetric and fluorometric detection. The research indicated that the specific ion affinity for Hg2+ ions in aqua systems and the multi-ion affinity for Hg2+ and Cu2+ in organic solvent results in drastic color and spectral changes. According to the data obtained, while the peak intensity increases at 390 nm, the peak intensity decreased at 272 nm in the absorption spectrum of 2-OxI-Rh and an increase in fluorescence intensity of 2-OxI-Rh were observed in the presence of Hg2+ and Cu2+ ions. The binding ratio of 2-OxI-Rh to Hg2+ and Cu2+ were found to be 1:1 according to Job's plot experiments. The binding constants were calculated using the Benesi-Hildebrand equation and found to be 2.15×104 M?1 for Hg2+ and 1.21×104 M?1 for Cu2+. Based on these concentration dependent fluorescence changes, the limit of detection (LOD) values were also calculated and found to be 3.36 μM for Hg2+ and 2.31 μM for Cu2+, which is the range of copper that should be in the blood (11.8–23.6 μM). As a result of all these studies, we can understand that prove 2-OxI-Rh, which is non-toxic, is a good selective candidate turn-on sensor that can be used for Hg2+ and Cu2+ detection in different solvent systems.
关键词： oxindole,Rhodanine,colorimetric,turn-on sensor.,mercury,chemosensor,copper
更新于2025-09-23 15:23:52
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A novel photosensitive dual-sensor for simultaneous detection of nucleic acids and small chemical molecules
摘要： Sensors that can rapidly and specifically detect nucleic acids and chemical molecules can revolutionize the diagnosis and treatment of diseases by allowing molecular-level informations to be used during the routine medicines. In this study, we demonstrated a novel dual-sensor that can be used to simultaneously detect any nucleic acids and chemical molecules whose binding aptamers can be found or synthesized. In the developed dual-sensor, the specifically designed PTG (a photosensitive azobenzene derivative carrying one photo-isomerizable azobenzene moiety, one threoninol terminal and one guanidinium terminal) molecules are introduced into the unwinding region of two T7 promoters, and two DNA bubbles are introduced upstream of the two T7 promoters. Without the target, the indicating gene in the dual-tensor would not be expressed since the binding with RNAPs (RNA polymerases) cannot melt the T7 promoter for the indicating gene due to the integration of the DNA double strands via the PTG molecules, manifesting the absence of the target nucleic acid and chemical molecule. While with the presence of the target nucleic acid and/or chemical molecule, the indicating gene would be expressed as the T7 promoter contained in the enlarged DNA bubble can be melted and transcribed by the bound RNAPs as the enlarged DNA bubble can help the separation of the two DNA strands, demonstrating the existence of target nucleic acid and/or chemical molecule.
关键词： Nucleic acids,DNA melting,Gene expression,DNA nanotechnology,Dual-sensor
更新于2025-09-23 15:23:52
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A novel non-enzymatic zinc oxide thin film based electrochemical recyclable strip with device interface for quantitative detection of catechol in water
摘要： Catechol, one of the major effluents released by various chemical and metal processing industries, causes severe pollution of groundwater. Monitoring of catechol in water using cost-effective, handheld sensor is demanding for the safety of the environment. In this work, non-enzymatic zinc oxide thin film based electrochemical strip sensor is developed on conducting glass substrate for detection of catechol. The preparation of strip without employing standard Pt or Ag/AgCl electrodes and simply depositing ZnO through wet chemical process represents a cost-effective innovative technique. The ZnO thin film is characterized using field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM) and grazing incidence X-ray diffractrometer (GIXRD). Catechol is electrochemically detected by means of cyclic voltammetry and amperometry. A prominent redox peak of the developed strip attributed to the detection of catechol is observed at -0.26 V in cyclic voltammetry. The strip is integrated with readout meter and an algorithm is built based on the experimentally observed linear variation of amperometric current with catechol concentration. The quantitative detection performance is demonstrated by testing 0.1-12 ppm catechol solutions.
关键词： Zinc oxide,Catechol,Electrochemical strip sensor,Amperometry,Cyclic voltammetry
更新于2025-09-23 15:23:52
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Blue Copper Peroksidase and Phthalocyanine Conjugate: Synthesis, Characterization and Applications
摘要： Trametes versicolor can degrade barks as a source for carbon necessity. Therefore it secretes lignin peroxidase, mangan peroxidase and laccase. The laccase enzyme was produced high yield at pH and glucose concentration 5 and 10 gL-1, respectively. In optimized medium, the enzyme activity was between 200-250 UL-1 when inducer was absent. It was seen that the activity reached 400 UL-1 when phenol used as an inducer. The molecular weight of purified laccase was found 80 kDa with SDS-PAGE and kinetic constant Km and Vmax values for ABTS were determined 3.66x10-4 μM and 1652 UL-1, respectively. Hence, due to these properties, these enzymes are widely used in industrial areas free or immolized. Laccase enzyme decolorization of 6 different dyes was carried out. A decolorization capacity of 50-99% was achieved by cultivation in 20 days using a beginning dye concentration of 20 ppm. The removal of color with active enzyme is obtained around 90%. Also laccase enzyme was conjugated amine functionalized low symmetrically phthalocyanine. This conjugate was examined both photodynamic therapy and chemosensor application. This conjugate fluorescence had a quantum yield of 0.32 (lifetime 3.59 ns) and generates efficiently singlet oxygen (quantum yield 0.4). The conjugate was successfully photodamage displayed in HeLa and HuH-7 cells in photodynamic therapy application. These results indicate that conjugate represent interesting agent with potential applications in photodynamic therapy. In addition that the chemosensor behavior of this compound to different metal ions has been studied and this conjugate display as fluorescence chemosensor for determination of Fe3+ions.
关键词： Conjugate,Zinc phthalocyanine,Metal Sensor,Laccase,Photodynamic Therapy
更新于2025-09-23 15:23:52
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Ordered mesoporous WO3/ZnO nanocomposites with isotype heterojunctions for sensitive detection of NO2
摘要： Ordered mesoporous WO3 nanocrystals have been successfully synthesized by a hydrothermal method using mesoporous silica of KIT-6 as a template and phosphotungstic acid as a precursor of WO3. The structure, morphology, and specific surface of WO3 nanocrystals were systematically characterized by XRD, SAXS, HR-TEM, and BET. To improve the sensing properties of WO3 to NO2, a series of different ZnO amounts were loaded on the mesoporous WO3 to construct nanocomposites with n–n heterojunction for the fabrication of NO2 sensors. The gas-sensing behaviors show that the sensor based on WO3/5 wt% ZnO composite to 1 ppm of NO2 not only exhibits the high response, but also has good selectivity and stability at operating temperature of 150 oC, which can be contributed to the large specific surface and porous channels provided by mesoporous structures, and the formation of n–n heterojunctions at interface between both oxides.
关键词： NO2 sensor.,ZnO,Mesoporous WO3,n–n isotype heterojunction
更新于2025-09-23 15:23:52
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High acetic acid sensing performance of Mg-doped ZnO/rGO nanocomposites
摘要： Mg-doped ZnO/reduced graphene oxide (rGO) nanocomposites were synthesized using a facile and cost-effective sol-gel procedure to detect acetic acid vapor. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) diffuse reflectance spectroscopy, and photoluminescence (PL) analysis were utilized to characterize morphologies, compositions of the nanocomposites, and optical properties of the synthesized nanostructures. The gas sensing measurements of spin-coated Mg-doped ZnO/rGO thin films were carried out for a temperature range of 150–350 oC at various acetic acid vapour concentrations. It was found that the Mg-doped sample with 20 wt. %/v of GO solution concentration exhibited the response/recovery time of 60 s/35 s with the best response of ~200% for 100 ppm of acetic acid at 250 oC.
关键词： Mg-doped ZnO/rGO,Gas sensor,Acetic acid,Nanoparticles
更新于2025-09-23 15:23:52