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Non-enzymatic sensing of dopamine by localized surface plasmon resonance using carbon dots-functionalized gold nanoparticles
摘要： A highly selective, sensitive, and rapid colorimetric sensor for the determination of dopamine (DA) was developed using the color change of S-doped carbon dots functionalized gold nanoparticles (S-CDs@Au NPs). The base of the method is the formation of a complex between the amine groups of dopamine with carboxylic groups of S-CDs@Au NPs followed by their aggregation with Fe3+ ions which acts as the linkers causing a red shift from 520 to 670 nm in the localized surface plasmon peak of S-CDs@Au NPs. The ratio of absorbance intensity at 670 nm to 520 nm was monitored as the analytical signal for determination of dopamine. The parameters affecting the analytical signal including reaction time, solution pH, the concentration of Au NPs and concentration of Fe3+ were optimized. At optimized conditions, the calibration curve was linear in the concentration range of 0.81-16.80 μM of dopamine. The detection and quantification limits were 0.23 μM and 0.77 μM, respectively. The intra-day and inter-day relative standard deviation (RSDs) at 5.0 μM of DA were 3.9% and 5.6%, respectively (n = 5). The applicability of the method for determination of DA in dopamine ampoule, urine and serum human samples was investigated.
关键词： Carbon dots,Localized surface plasmon resonance,Colorimetric chemical sensor,Dopamine,Gold nanoparticles
更新于2025-11-14 15:18:02
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Improvement of Sensing Performance of Impedancemetric C2H2 Sensor Using SmFeO3 Thin-Films Prepared by a Polymer Precursor Method
摘要： A sensitive an impedancemetric acetylene (C2H2) gas sensor device could be fabricated by using perovskite-type SmFeO3 thin-film as a sensor material. The uniform SmFeO3 thin-films were prepared by spin-coating and focusing on the effects of polymer precursor solutions. The prepared precursors and thin-films were characterized by means of thermal analysis, Fourier-transform infrared spectroscopy, ultraviolet–visible spectroscopy, X-ray diffraction analysis, scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that particle growth and increase in homogeneity of the prepared thin-film could be accelerated by the addition of acetyl acetone (AcAc) as a coordination agent in the polymer precursor solution. Moreover, the highly crystallized thin-film-based sensor showed good response properties and stabilities to a low C2H2 concentration between 0.5 and 2.0 ppm.
关键词： polymer precursor,acetyl acetone,thin-film,gas sensor,acetylene,perovskite-type oxide,AC impedance
更新于2025-11-14 15:15:56
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Selective H2S-sensing performance of Si nanowires through the formation of ZnO shells with Au functionalization
摘要： A novel gas sensor fabricated from ZnO-shelled Si nanowires (SiNWs) is presented. After coating a thin layer of Au on the surfaces of Si NWs, ZnO layers were formed on the surfaces of p-SiNWs by thermal evaporation of Zn powders and a subsequent oxidation process. Microscopic analysis confirmed the successful formation of ZnO-Si core-shell NWs with Au nanoparticles present on the shell surface. The gas sensing performance of the gas sensor fabricated using the p-Si/n-ZnO core-shell NWs was evaluated for various gases. The sensor exhibited outstanding response and selectivity to H2S gas. The gas sensing mechanism was evaluated in detail and attributed to various factors, including the formation of ZnO/Si and Au/ZnO heterojunctions and the chemical attraction between ZnO and Au. The results demonstrate a new sensing material for H2S detection in various fields that can be easily incorporated into Si-based devices.
关键词： Gas Sensor,Si Nanowires,ZnO,Sensing Mechanism,Shell,Au
更新于2025-11-14 15:15:56
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Soft tissue cutting efficiency by 980?nm laser with carbon-, erbium-, and titanium-doped optothermal fiber converters
摘要： Objectives: The use of near-IR diode lasers for contact soft tissue surgery is attended by a risk of severe thermal damage of surrounding tissues due to the low cutting efficiency of these lasers. To increase the cutting efficiency tips of a near-IR lasers in contact surgery special (converters) which transform laser light to heat are used. The present in vivo study evaluated temperature dynamics and soft tissue cutting efficiency of 980 nm diode laser equipped with standard carbon- and novel erbium- and titanium-doped converters. Materials and Methods: For in vitro treatment on soft tissue (chicken thigh), 980 nm diode laser was used. The radiation was delivered to the tissue by a quartz fiber with a core diameter of 400 ± 5 mm. The carbon-, erbium-, or titanium-doped converters were mounted at the fiber distal end. The converters temperature was measured by IR-sensor integrated into the laser radiation delivery system. The temperature dynamics of each converter during soft tissue treatment was evaluated. The converter was in contact with the soft tissue surface and moved across the surface of soft tissue with a speed of 1, 3, or 6 mm/s. The average power of laser radiation was 0.3, 1.0, or 4.0 W. The collateral thermal damage of treated soft tissues was evaluated using NTBC stain. The width and depth of coagulation and ablation zones of laser wounds was determined. The soft tissue cutting efficiency with different converters was calculated. Results: The cutting efficiency, collateral damage, and converter temperature in contact with soft tissue change depending on the type of converter, the power of laser radiation and the converter movement speed along the temperature tissue (1,980 ± 154 °C), at which a tissue cut takes place, was fixed for Ti-doped converter for laser power of 4.0 W and movement speed of 1 mm/s. Minimal converter temperature (540 ± 30 °C), at which a tissue cut takes place, was fixed for Ti-doped converter for laser power of 1.0 W and movement speed of 6 mm/s. Maximal depth of coagulation (0.72 ± 0.10 mm) was fixed for Ti-doped converter for laser power of 4.0 W and movement speed of 1 mm/s. Minimal depth of coagulation (0.11 ± 0.02 mm) was fixed for C-doped converter for laser power of 0.3 W and movement speed of 3 mm/s. Maximal cutting efficiency (0.57 mm3/W) was fixed for Er-doped converter for laser power of 1.0 W and movement speed of 1 mm/s. Minimal cutting efficiency (0.02 mm3/W) was fixed for C-doped converter for laser power of 4.0 W and movement speed of 6 mm/s. Conclusion: All three studied types of converters can be used for contact surgery of soft tissues by 980 nm diode laser. Er-doped and Ti-doped converters are more resistant to laser heating then C-doped converter, they dissect soft tissue more effectively. This will also expand the potential of everyday routine clinical procedures, making them safer, faster, and easier. These converters can be used in general surgery, plastic surgery, dermatology, angioplasty, dentistry, neurosurgery, etc. Lasers Surg. Med. 9999:1–16, 2018. ? 2018 Wiley Periodicals, Inc.
关键词： soft tissue,coagulation,surgery,efficiency,IR-sensor,diode laser,cutting,converter,fiber
更新于2025-10-24 16:41:07
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Ultra-selective fiber optic SPR platform for the sensing of dopamine in synthetic cerebrospinal fluid incorporating permselective nafion membrane and surface imprinted MWCNTs-PPy matrix
摘要： Surface plasmon resonance (SPR) based dopamine sensor is realized using the state-of-art technique of molecular imprinting over an optical fiber substrate. Polypyrrole (PPy) is depicted as an effective polymer for the imprinting of dopamine through a green synthesis approach. Sensitivity of the probe is enhanced by the augmenting effect of surface imprinting of dopamine in polypyrrole over multiwalled carbon nanotubes (MWCNTs). To ensure the permselectivity of the probe towards dopamine molecules, a cation exchange polymer, nafion, is utilized as a membrane over imprinted sites to reduce the interference from anionic analytes like ascorbic acid and uric acid at physiological pH. The probe is characterized for a wide range of dopamine concentration from 0 to 10-5 M in artificial cerebrospinal fluid. Various probe parameters are varied to maximize the sensitivity of the sensor. The sensor possesses 18.9 pM as the limit of detection (LOD) which is lowest of those reported in the literature. The manifestation of sensing probe over an optical fiber along with the improved LOD makes the approach highly advantageous in terms of stability, repeatability, online remote monitoring, fast response, and miniaturization for its in vivo/in vitro applications in clinical sensing of dopamine.
关键词： surface plasmon,dopamine,Optical fiber,polypyrrole,nafion,molecular imprinting,sensor,multiwalled carbon nanotube
更新于2025-10-22 19:40:53
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A reaction-based turn-on fluorescent sensor for the detection of Cu (II) with excellent sensitivity and selectivity: Synthesis, DFT calculations, kinetics and application in real water samples
摘要： A reaction-based turn-on fluorescent chemosensor RhB-Cu, starting from rhodamine B (RhB), for Cu2+ was easily synthesized in two steps. The sensor could selectively detect Cu2+ with a 100-fold fluorescence enhancement among the common metal ions, exhibiting an extremely low detection limit of 4.7 nM. To the best of our knowledge, this was the best record for the detection of Cu2+ with organic fluorescent sensors. There was a 1:1 binding stoichiometry between RhB-Cu and Cu2+ with an association constant of 6.42 × 104 M-1. Noteworthy, it could distinguish Cu2+ from Cu+, which was hard to realize in the previous studies. In addition, the detection mechanism was proposed based on mass spectrometric analysis and density functional theory (DFT) calculations. Kinetic studies were conducted to obtain the activation energy, enthalpy and entropy, so as to elucidate the solvent effect. Interestingly, the kinetic compensation effect (KCE) was uncovered in this work. Finally, RhB-Cu was proved to have the capability to work in real water samples. It would highly contribute to the even better design of fluorescent sensor for Cu2+ in future.
关键词： fluorescent sensor,solvent effect,kinetic compensation effect (KCE),copper,density functional theory (DFT),PET mechanism
更新于2025-10-22 19:38:57
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Sensor Localization for Highly-Deformed Partially Calibrated Arrays with Moving Targets
摘要： In this letter, a sensor localization technique for highly-deformed partially calibrated arrays with multiple moving targets is proposed. The deformed array is divided into several subarrays. The first subarray is composed of the pre-calibrated sensors, while the sensors in the other subarrays are uncalibrated. The positions of the sensors are estimated from the phase differences between the pre-calibrated sensors and the uncalibrated sensors. The phase ambiguities caused by the highly-deformed sensor positions can be solved using the subspace orthogonality and the movement of multiple targets. Simulation results evaluate the performance of the proposed method, and the Cramer–Rao bounds are compared.
关键词： highly-deformed sensor array,partially calibrated sensor array,phase ambiguity,Sensor localization
更新于2025-09-23 15:23:52
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Polymeric fluorescent film sensor based on poly(azomethine-urethane): Ion sensing and surface properties
摘要： A polymeric film sensor containing poly(azomethine-urethane) was easily fabricated using the dip-coating technique and ion sensing property of this film toward different metal cations investigated. Fluorescence measurements showed that fluorescent film sensor has been exhibited dual emission wavelengths at 540 and 582 nm and metal cation sensing behavior of this film studied using these two wavelengths. Also, fluorescent film sensor was showed selectivity and sensitivity toward iron (III) ions in deionized water with excellent photostability. The detection limit of the polymeric sensor was found as 86.15 and 28.90 μM at these wavelengths. The results indicated that chemosensor can be successfully applied for the detection of iron (III) ions in deionized water. Contact angle measurements of the film probe were also evaluated to investigate the surface hydrophilicity or hydrophobicity of the film.
关键词： Poly(azomethine-urethane),Fe (III) sensor,Film sensor,Surface property
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - Va?ster?s (2018.9.3-2018.9.6)] 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - Design of Low-profile Antenna with Multi-directional Beam
摘要： An planar antenna having a low-pro?le structure using loop elements is proposed. The proposed antenna is vertically polarized and has four directional beams for sensor nodes. The thickness of the antenna is only 3.2 mm (0.11 effective wavelength) resulting in a low-pro?le structure. Simulated and measured average gain of 8.0 dBi and 5.6 dBi are obtained, respectively.
关键词： wireless sensor network,sensor node,low-pro?le antenna,vertical polarization,multi-directional beam
更新于2025-09-23 15:23:52
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A colorimetric and fluorometric oligothiophene-indenedione-based sensor for rapid and highly sensitive detection of cyanide in real samples and bioimaging in living cells
摘要： A new simple oligothiophene-indenedione-based sensor 3TI has been synthesized for the highly reactive and selective detection of cyanide anion (CN?) in 70% aqueous media. The sensor 3TI displays distinct colorimetric and fluorometric detection of CN? due to the addition of CN? to the electron-deficient indenedione-vinyl group of 3TI, which hampers intramolecular charge transfer (ICT) efficiencies. The recognition mechanism of 3TI for CN? was confirmed by the optical measurements, 1H NMR titration, FTIR spectra, HRMS analysis, and TD-DFT calculations. The sensor 3TI for CN? shows the outstanding advantages of high fluorescence brightness, fast response time (30 s), low detection limit (31.3 nM), minimal pH dependence in the physiologically relevant range, and excellent selectivity in presence of other competitive anions. Encouraged by these desirable sensing properties, the 3TI has been successfully used for determination of CN? in real water and food samples, silica-based sensing kits and fluorescence imaging in living cells with satisfactory results.
关键词： Fluorometric sensor,Cyanide,Oligothiophene-indenedione,Colorimetric sensor,Real sample,Live-cell imaging
更新于2025-09-23 15:23:52