Sensors and Actuators Reports最新文献

Nickel is a toxic heavy metal that may cause negative health outcomes including cancer upon exposure [1]. Square wave voltammetry was used to assay DNA directly extracted from nickel-exposed nematodes that had originated from either high or low Ni-containing environments in order to assess the role of evolutionary genetics in the Ni toxicity process. Extracted DNA was immobilized on pyrolytic graphite (PG) electrodes following layer by layer (LbL) protocols and then electrochemically oxidized in the presence of Ru(bpy)³⁺ to generate electrocatalytic oxidative currents at ∼+1.05 V vs. SCE. Both C. elegans and P. pacificus nematodes were utilized, each with a volcanic or cosmopolitan soil source strain. DNA oxidative peak currents (I_p) increased for all nematode strains upon exposure to 50 μg/L Ni²⁺, but those originating from volcanic soils exhibited significantly (40–50%) lower I_p upon Ni²⁺ exposure compared to similarly exposed nematodes from cosmopolitan soils. Further SWV analysis was performed on DNA from a series of C. elegans N2xCB4856 recombinant inbred advanced intercross line populations (RIALs). A continuum of I_p magnitude was seen as a function of Ni²⁺ exposure among the RIAL strains indicating Ni-tolerance is complex and affected by multiple loci. The majority of the DNA from Ni-exposed individual RIAL strain cultures produced an increase in oxidative current in comparison to DNA from analogous Ni-unexposed cultures of the same RIAL strains. Liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis on acid hydrolyzed nematode DNA provided validation of the electrochemical findings. Guanine and oxidatively damaged guanine content were monitored via appropriate m/z mass transitions. Guanine content in all Ni-exposed RIAL DNA was lower, while oxidatively damaged guanine was elevated compared to unexposed nematodes in all but one analyzed RIAL. Combined, the complementary electrochemical and MS/MS data provide evidence that evolutionary genetics leads to genetic protection from environmental toxicants, suggesting a possibility that multiple genes are involved in the protection of the organism from Ni exposure.

This paper presents a new modified electrode that combines the high electrical conductivity of carbon nanotubes (CNTs) with the catalytic sites of WS₂ (named WS₂/CNTs) for isoniazid detection. Electrochemical and electroanalytical properties of the WS₂/CNTs/glassy carbon electrode (GCE)-modified electrodes were investigated by cyclic voltammetry and differential pulse voltammetry (DPV). The composite material was characterized by Raman spectroscopy, X-ray diffractometry (XRD), and scanning electron microscopy . The electrochemical performance of the WS₂/CNTs/GCE sensor exhibited a limit of detection of 0.24 μM with a linear range from 10 to 80 μM of isoniazid using DPV. This sensor provided enhanced stability and electrocatalytic activity for isoniazid oxidation reactions. Recoveries ranging from 96.9 to 104.5% were calculated, demonstrating satisfactory accuracy of the proposed method. The improvement of electrochemical activity was assigned to synergic effects obtained by combining the catalytic sites from WS₂ and the known electrical conductivity and large surface area of the CNTs, resulting in an anticipation of the oxidation peak of isoniazid in about 400 mV in comparison with bare GCE.

Surface plasmon resonance (SPR) has been utilized extensively in bioanalysis since the early 90s due to its unique combination of label-free, highly sensitive, and robust detection. In recent years, SPR has been coupled with and complimented by several other techniques that provide the qualitative and molecular information that SPR lacks. In this paper, advances in studies that present molecular identification to quantitative measurements by SPR are reviewed. In particular, coupling of SPR measurements and MALDI mass spectrometry (MALDI-MS) has been broadly explored where plasmon-assisted ionization upon gold substrates appears to demonstrate many added benefits. Imaging SPR analysis, upon coupling, has contributed to new analytical capability that proves to be powerful with elevated throughput. The combination of SPR and Raman spectroscopy has also found a wide range of applications in providing molecular information that promotes quantitative analysis. Similar to MALDI, the plasmonic thin-film metal substrates provide a desired surface structure and property for Raman enhancement, improving subsequent molecular recognition. Instrumentation advancements and improvements in coupling efficiency has facilitated a series of SPR sensor developments where the plasmonic properties of the surface contribute uniquely to the performance of the coupled technique.

For the first time, renewable carbon (RC) from bamboo-biomass modified with copper nanoparticles (CuNPs) has been prepared via a chemical reduction step for the electroanalytical detection of dopamine (DOP), fluoxetine (FXT) and escitalopram (EST). The synthesized RCCuNPs nanocomposite morphology and structural composition were characterized by FEG-SEM along with EDS analysis. The electroanalytical behavior of the target analytes was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The analytical range of detection of DOP, FXT, and EST was 0.05–5.0, 0.1–10, and 0.02–5.0 µmol L⁻¹, respectively. The limits of detection (LOD) were found to be 0.04, 0.05, and 0.25 µmol L⁻¹, respectively. In addition, the standard addition method was used for the detection and recovery of DOP in synthetic human urine and EST in tap water samples. The synergistic effect of CuNPs coupled with the highly porous RC material provided a sensitive, low-cost, and easy to prepare sensing platform for detecting target analytes in clinical and environmental samples.

The exoskeleton plays an essential role in the field of physical rehabilitation. Several actuators are used for the exoskeleton application, but the pneumatic muscle actuator has proved to be the best due to its high power to weight ratio, compliance, and safe operation. The objective of this paper involves the fabrication and experimental characterization of a pneumatic muscle actuator to actuate an exoskeleton for the elbow joint. This paper presents the development and testing of twelve pneumatic muscles of varying materials and sizes, to find the best combination to suit the intended application. The characterization process involved several tests, which related force, deflection, and pressure at various loading conditions. A modular test rig was developed to conduct all the tests with minor adjustments to the test setup. The study also involved designing and developing an elbow exoskeleton to test the pneumatic muscle in the real-world scenario. The exoskeleton is designed with a novel hinge to compensate for the antagonistic nature of the pneumatic muscle actuator. The tests showed the muscles with higher tensile modules bladders having a lower hysteresis and better load handling capability, but these suffered from lower contraction and force characteristics. The styrene-based muscle with a 12mm bladder (S12LB) showed the best force and deflection characteristics at various pressures and loading conditions. The styrene bladder has a modulus closer to the skeletal muscle, therefore demonstrating higher compliance and making it a preferred choice for the exoskeleton application

Efficient direct electrical communication between an enzyme redox center and an electrode is of great interest from the viewpoints of application to reagentless biosensors and biofuel cells. To immobilize redox enzymes in a favorable orientation for electron transfer at the electrode surface, we reconstituted apo-horseradish peroxidase (apo-HRP) onto a hemin cofactor linked to pyrroloquinoline quinone (PQQ) spacer at an indium-tin-oxide (ITO) electrode surface. The bioelectrocatalytic activity of reconstituted HRP for H₂O₂ reduction was evaluated by means of amperometry at +0.150 V (vs. Ag|AgCl), which value is larger than that for the redox potential of PQQ (ca. –0.140 V). The complex-formation reaction rate of reconstituted HRP with H₂O₂ enhanced in comparison with that for the hemin linked to PQQ electrode without apo-HRP by a factor of 200. PQQ served as the part of spacer for the insertion of hemin into a certain desired position in apo-HRP. Although native HRP cannot electrochemically communicate with the ITO electrode in general, the quasi-direct electron transfer from the ITO electrode to reconstituted HRP oxidized by H₂O₂ was also achieved most likely by electron hopping and/or resonant transport without the redox mediation thanks to the π-conjugated PQQ molecule in the spacer.

Multiplex assays often rely on expensive sensors incorporating covalently linked fluorescent dyes. Herein, we developed a self-assembling aptamer-based multiplex assay. This multiplex approach utilizes a previously established split aptamer sensor in conjugation with a novel split aptamer sensor based upon a malachite green DNA aptamer. This system was capable of simultaneous fluorescent detection of two SARS COVID-19-related sequences in one sample with individual sensors that possesses a limit of detection (LOD) in the low nM range. Optimization of the Split Malachite Green (SMG) sensor yielded a minimized aptamer construct, Mini-MG, capable of inducing fluorescence of malachite green in both a DNA hairpin and sensor format.

Researchers studying cellular life cycles need to be able to monitor the phases of a cell cycle rapidly and accurately. Many of the techniques currently used to monitor the cell cycle require the use of labels and would be difficult to automate. Microwave cytometry is a promising new approach to label free monitoring of cell life cycles. This paper presents results of multiple frequency microwave measurements of two lifecycle stages of Trypanosoma brucei, a unicellular eukaryotic parasite found in sub-Saharan Africa. A microwave flow cytometer was used to show bloodstream form (BSF) and procyclic form (PCF) T. brucei have frequency dependent permittivity and impedance from 800 MHz to 7.65 GHz. The two cell forms had a strong dependence on the imaginary part of permittivity at 2.38 GHz and below and a strong dependence on the real part of permittivity at 5.55 GHz and above. Three PCF cell lines were tested to verify that the differences between the two cell forms were independent of cell strain. Additionally, impedance measurements were used to improve cell classification in cases where the permittivity of a cell cannot be detected. Quadratic discriminate analysis was employed to validate the ability to classify cells forms, with maximum cross-validation errors of 15.4% and 10% when using one and three PCF strains, respectively.

We report herein an investigation on the ozone gas-sensing performance at room temperature of SnO₂ nanoparticles assisted by a light-emitting diode. X-ray diffraction and high-resolution transmission electron microscopy analyses indicated the nanocrystalline characteristics of the SnO₂ particles after heat treatment. Besides, optical measurements pointed out that the nanoparticles presented an optical gap of approximately 3.8 eV with a broad photoluminescence emission at around 625 nm, which was linked to the presence of oxygen vacancies, suggested by XPS analysis. With regard to the light-assisted gas-sensing measurements, electrical analysis revealed a clear dependence of the ozone sensing performance on the wavelength of the source of illumination chosen, with the highest ozone response being reached upon excitation in the ultraviolet region. Theoretical calculations showed that the (110) surface could increase the stability of photogenerated carriers and contribute to enhancing the gas-sensing features under ultraviolet excitation due to the presence of [SnO₆] and [SnO₅] clusters, which are capable of inducing an electron-hole dissociation and a reliable chemical environment for O₃ interaction.

This revision covers the agriculture system, the losses due to insect pest, the pheromone definition and how they can be deployed. Specially, this work focus in pheromones from stink bug Euschistus heros. The use of different techniques for pest control in agriculture seeks safety and environmental preservation. The stink bug E. heros is one of the major pests that affects crops in Brazil. This insect releases pheromone to mate in low amounts. A promising and efficient alternative for the detection of this volatile compound is the use of nanosensors. This paper provides a review of the most recent works in nanosensors used for detection insect pheromones, including gas sensors with sensitive coatings in nanoscale. Also, other applications of gas nanosensors in pheromone detection in agriculture are described. Nanosensors are potential solutions for pest management and can contribute to developing innovative and technological solutions for agriculture.