Peak Current Intensity Research Articles

Nucleic acid-functionalized nanoscale porous carbon-based electrochemical genosensor for detection of Nocardia spp. in real samples

In this study, a porous carbon derived from a metal-organic framework (PCMOF) as a target-responsive material functionalized with Nocardia particular antisense ssDNA oligonucleotide (ssDNA capture probe) was developed to construct a simple genosensor based on biogatekeeper strategy for sensitive detection of Nocardia in complex biological samples. The PCMOF with suitable pores volume was used to encapsulate electroactive dye methylene blue (MB), and the ssDNA capture probe was used as a gatekeeper to cap PCMOF. Without the presence of Nocardia target, the electrochemical signal of trapped MB was high. Upon adding the target, the hybridization of ssDNA capture probe and target led to the formation of a probe-target double-stranded (dsDNA) structure which dissociated from PCMOF and allowed MB molecules to be released. Therefore, the electrochemical signal of the genosensor decreased. The detection of Nocardia was accomplished by observing variations in the MB peak current intensity in a dose-dependent manner. For this genosensor, a linearity range from 10−18 to 10−7 M for synthetic ssDNA target and 10 to 108 copies/mL for two standard isolates, Nocardia farcinica PTCC 1309 and Nocardia brasiliensis ATCC 19296 as well as for clinical isolates (identified as Nocardia otitidiscaviarum) was observed, respectively. The detection limit (DL) values were 0.54 aM for synthetic ssDNA target and 5, 7, and 4 copies/mL for N. farcinica, N. brasiliensis, and N. otitidiscaviarum, respectively. This genosensor was also characterized by good specificity, reproducibility, and stability.

Investigation on the Potential of Some N-phenylalkanehydrazides as Superoxide Anion Radical Scavengers and Glutathione Peroxidase Binders with ADME Prediction: Comparison with Vitamin C

Objective: An investigation on the antioxidant activity and ADME properties of some N-phenylalkanehydrazides (NPhs) in comparison with ascorbic acid was carried out. Materials and Methods: The power of the compounds to scavenge the superoxide anion radical was examined using cyclic voltammetry. Furthermore, molecular docking was used to examine how NPhs bind to the antioxidant enzyme glutathione peroxidase (GPx). Finally, ADME properties were predicted using the SwissADME webserver. Results: The results showed that the studied compounds had significantly higher EC50 values than Vitamin C and displayed spontaneous binding with GPx with binding energy similar to ascorbic acid. Also, substantial values emerged from the predictive analysis of drug-likeness and bioavailability characteristics. Discussion: First, the EC50 of the compounds under study was determined by assessing the decrease in the anodic current peak intensity; this demonstrated significant radical scavenging activity. Next, the electrostatic way of binding with ROS radical and with antioxidant enzyme was disclosed by the binding free energies; however, the oxygen and nitrogen atoms in the compounds' structures might make many conventional hydrogen bonds with amino acids. Finally, NPh (a) followed all the rules for drug-likeness and bioavailability estimates, making it a promising moiety for synthesising new antioxidant chemicals. Conclusion: The current study is a hybrid of experimental and computational methods that complement each other perfectly.

Electrochemical modification of glassy carbon electrode (GCE) with cobalt ferrite/ reduced graphene oxide composite material comprising polyaniline for dissolved oxygen analysis in water

The study focuses on the enhancement of glassy carbon electrode (GCE) performance through electrochemical modification with a composite material comprising polyaniline (PANi) conducting polymer and CoFe2O4/reduced graphene oxide (CF/rGO) for the analysis of dissolved oxygen in water. Characterization methods, including Fourier-transform infrared spectroscopy (FT-IR) and Scanning Electron Microscope (SEM), were employed to elucidate the chemical bonding of functional groups within the PANi membrane and modified PANi on the surface of the GCE electrodes as well as examine the surface morphology. Electrochemical studies were conducted to evaluate the electrochemical activity of the modified electrodes, GCE/PANi and GCE/PANi/CF/rGO. Electrochemical studies were conducted to evaluate the electrochemical activity of the modified electrodes, GCE/PANi and GCE/PANi/CF/rGO. Notably, the electrochemically active surface area of the modified electrodes significantly increased, from 0,0756 cm2 (GCE), 0,1106 cm2 (GCE/PANi) to 0,1774 cm2 (GCE/PANi/CF/rGO), in addition the peak current intensity (Ip) on the modified electrodes GCE/PANi and GCE/PANi/CF/rGO also increased compared to the unmodified electrode (GCE), Ip increased from 0,0767.10-3 (A) to 0,18 x 10-3 (A), resulting in an increased ability to sense dissolved oxygen in water.

Sensitive sensing of GLA and ISL based on highly conductivity nitrogen-doped carbon synergistic dual-template molecularly imprinted ratiometric electrochemical sensor

A novel ratiometric Molecularly Imprinted Electrochemical sensor for the specific marker of Glycyrrhiza glabra L. was developed in this work. To achieve simultaneous detection of two analytes on one sensor, we constructed a double template molecular imprinted electrochemical sensor with glabridin (GLA) and isoliquiritin (ISL) as templates. Further, Ferrocene/ZIF-8 (Fc/ZIF-8) composites were prepared via a one-pot solvothermal reaction and coated on the surface of a glassy carbon electrode (GCE), and the oxidation of Fc was presented as the internal reference signal. Nitrogen-doped carbon (NOC) with high conductivity was further loaded on the modified GCE. Based on theoretical exploration and computer directional simulation of density functional theory (DFT), the optimal functional monomer and the best ratio of double template molecules to functional monomer were screened. Under optimal conditions, the sensor produced electrochemical curves when exposed to a solution containing GLA and ISL. As the concentration of GLA and ISL increased, the peak current intensity of GLA and ISL (IGLA and IISL) also increased, while the peak current intensity of Fc (as a reference signal) remained relatively constant. The values of IGLA/IFc and IISL/IFc showed excellent linear relationships with GLA and ISL concentrations in the range of 0.1–160 μM and 0.5–150 μM, respectively. The detection limits were 0.052 μM and 0.27 μM (S/N = 3), respectively. Due to the imprinting effect of MIP and the existence of a reference signal, the sensor exhibited excellent selectivity and anti-interference ability and was successfully applied to the quality evaluation of Glycyrrhiza glabra L.

Effective polysulfide control in lithium–sulfur batteries utilizing BiFeO3 nanoparticles

Lithium–sulfur batteries (LiSBs) offer high energy density, cost-effectiveness, and eco-friendliness, making them promising for future energy storage. This study explores using BiFeO3 (BFO) nanoparticles (NPs) to tackle challenges such as lithium polysulfides (LiPs) and shuttle issues in LiSBs. It employs a solid-state melt diffusion technique, encapsulates sulfur in single-walled carbon nanotubes (SCNTs), and utilizes BFO for effective polysulfide control. Herein, composite cathodes of sulfur (S)/SCNTs (abbr. SCNT) were fabricated, and cells were designed using a BFO-coated separator (SCNT-BFS). In addition, a cathode modification was performed with composite S/SCNTs/BFO (SCNT-BF), and a comparative analysis was conducted to assess the effectiveness of the BFO in the separator and the cathode. Cyclic voltammetry measurements revealed that the increased current peak intensity at lower reduction potential in SCNT-BF and SCNT-BFS indicated control of higher-order LiPs (Li2Sx, where 4 ≤ x ≤ 8), resulting in the generation of more stable lower-order products (Li2S2/Li2S). The charge/discharge analysis revealed controlled LiPs, resulting in high-capacity retention in SCNT-BF (∼75%) and SCNT-BFS (∼88%) over 200 cycles, which yielded capacities of 526 and 700 mAh/g at C/8 (1C = 1675 mA/g). These promising results suggest that incorporating BFO into the cathode and separator can advance the commercialization of durable LiSBs.

‘Accurate proton range shift verification by using a two-layer dense-pixel LYSO compton camera prototype

ObjectiveCompton camera (CC)-based prompt gamma imaging (PGI) is promising to realize real-time in-vivo range verification during proton therapy. Lutetium–yttrium orthosilicate (LYSO)-based CC has advantages in high detection efficiency and position resolution. However, few LYSO CC-based PGI experimental evaluations have been investigated. ApproachWe built a 46 × 46 two-layer dense-pixel LYSO CC prototype for PGI. We attempt the first-ever effort to conduct the proton range shift verification experiments with the LYSO CC prototype. A 13 MeV proton beam with a cross-section of 1 mm2 produced by the Compact Pulsed Hadron Source (CPHS) and a lead collimator irradiates a block of graphite, a block of polymethacrylates (PMMA) and a block of fresh pork, respectively. A range shift varied from 1 mm to 5 mm of the proton beam is used to evaluate the performance of the prototype in PGI. The peak current intensity was about 640 nA. The pulse width and frequency were 100 μs and 1 Hz, respectively. The rate of incident protons in each measurement is about 3.6 × 108/s, and the corresponding delivered dose is about 5.8 Gy. Main resultsThe built LYSO CC prototype can distinguish the displacement of the Bragg peak in 2 mm (reaching 1 mm) at a distance of about 13 cm, and can accurately reconstruct the positions of the Bragg peak with a mean deviation of 0.2 mm in the eighteen groups of experiments. SignificationThe experiments demonstrate the feasibility of the developed two-layer dense-pixel LYSO CC in realizing accurate range shift monitoring and show its potential in range verification during clinical proton therapy and high particle rate proton therapy (e.g., FLASH proton therapy).

Synergistic behavior of organic and inorganic constituents in improving the charge transfer ability of Polyoxometalate-Based ionic liquids

The electron transfer kinetics and electronic properties of (3-sulfonic acid) propyl bipyridine-12tungstophosphoric acid (BPyPS-PW) as a novel organic–inorganic ionic liquid have been investigated. Cyclic voltammetry (CV) revealed that BPyPS enhanced the oxidation peak currents of tungstophosphoric acid (PW) by 1.4-fold. According to linear sweep voltammetry (LSV), BPyPS-PW exhibited significantly lower tafel slope (96 mV) than BPyPS and PW (144 and 119 mV, respectively). This indicates that the current density increases more rapidly with overpotential, pointing the superior electron transfer ability of BPyPS-PW. Further, it showed about 1.5- and 1.2-fold higher charge transfer coefficient than BPyPS and PW. Differential pulse voltammetry (DPV) and square wave voltammetry (SWV) showed increased peak current intensities for the hybrid compared to both constituents. Electrochemical impedance spectroscopy (EIS) indicated that BPyPS-PW has the lowest charge transfer resistance (RCT, 685 Ω), Warburg impedance (ZW, 1.87 Ω), electrolyte solution resistance (RS, 86 Ω), and double-layer capacitance resistance (ZC, 38.73 Ω) among the studied compounds, indicative of its reduced electron transfer resistance at the electrode/electrolyte interface. According to chronoamperometry (CA), BPyPS-PW exhibited higher electrostability, with only 21.48 % current decay after 120 s, while BPyPS and PW experienced a stronger decay (50.09 % and 24.57 %, respectively), attributed to a synergistic behavior of the constituents that results in a larger charge transfer network and more electron active centers. These findings are crucial for the design of new ionic liquid electrolytes to be used in electrochemical applications.

Synthesis and structure of anhydrous Zn2EDTA metal-organic framework

Metal-organic frameworks (MOFs) have gained significant attention in materials science due to their unique properties such as high surface area, porosity, and tunable electrochemical characteristics. Among various MOFs, Zn-EDTA compounds have shown potential for electrochemical applications. This paper presents the accident discovery and investigation of a new anhydrous Zn2(EDTA) MOF and its electrochemical performance as an electrode material for aqueous sodium-ion batteries. The study systematically explores the influence of pH and stoichiometric ratio on the formation of Zn2(EDTA) and Zn2(EDTA)(H2O) MOFs using X-ray diffraction analysis. The single-phase anhydrous Zn2(EDTA) compound is synthesized, offering advantages over the hydrated form regarding stability and electrochemical activity. Zn2(EDTA) structure is characterized, revealing a 3D network of channels suitable for interstitial ionic mobility. Thermogravimetric analysis (TGA) is used to study the thermal behavior of Zn2(EDTA), showing two weight loss steps attributed to water and carbon dioxide elimination during decomposition. Electrochemical measurements using cyclic voltammetry in alkaline and neutral electrolytes demonstrate the electrochemical activity of Zn2(EDTA) as an anode material for aqueous sodium-ion batteries. The results suggest that the electrochemical process in both electrolytes involves the reversible stripping/deposition of zinc ions. The anhydrous Zn2(EDTA) MOF exhibits higher peak current intensities and more positive potentials than the hydrated form. The study provides valuable insights for synthesizing and controlling Zn2(EDTA) MOF formation, opening the prospects for searching for new structures in considered-to-be-studied phase regions.

Construction of a Dual-Mode Biosensor with Ferrocene as Both a Signal Enhancer and a Signal Tracer for Electrochemiluminescent and Electrochemical Enantioselective Recognition.

We demonstrate for the first time the construction of a dual-mode biosensor for electrochemiluminescent (ECL) and electrochemical chiral recognition of l- and d-isomers of amino acids, with ferrocene (Fc) as both a signal enhancer and a signal tracer. With the dissolved oxygen as a coreactant, ZnIn2S4 acts as the ECL emitter to generate a weak cathodic ECL signal. Fc can enter into the β-cyclodextrin (β-CD) cavity on ZnIn2S4-modified electrode as a result of host-guest interaction. Since Fc can promote H2O and O2 to produce abundant reactive oxygen species (ROS) (e.g., O2·- and ·OH), the ECL signal of ZnIn2S4 can be further amplified with Fc as a coreaction accelerator. Meanwhile, Fc molecules on the β-CD/ZnIn2S4-modified electrode can be electrochemically oxidized to Fc+ to produce a remarkable oxidation peak current. When l-histidine (l-His) is present, the matching of the l-His configuration with the β-CD cavity leads to the entrance of more l-His into the cavity of β-CD than d-histidine (d-His), and the subsequent competence of l-His with Fc on the Fc/β-CD/ZnIn2S4-modified electrode induces the decrease in both Fc peak current and ZnIn2S4-induced ECL intensity. This dual-mode biosensor can efficiently discriminate l-His from d-His, and it can sensitively monitor l-His with a detection limit of 7.60 pM for ECL mode and 3.70 pM for electrochemical mode. Moreover, this dual-mode biosensor can selectively discriminate l-His from other l- and d-isomers (e.g., threonine, phenylalanine, and glutamic acid), with potential applications in the chiral recognition of nonelectroactive chiral compounds, bioanalysis, and disease diagnosis.

Electrochemical Determination of 17-β-Estradiol Using a Glassy Carbon Electrode Modified with α-Fe2O3 Nanoparticles Supported on Carbon Nanotubes.

In this study, a novel electrochemical assay for determining 17-β-estradiol (E2) was proposed. The approach involves modifying a glassy carbon electrode (GCE) with a nanocomposite consisting of α-Fe2O3 nanoparticles supported on carbon nanotubes (CNTs)-denoted as α-Fe2O3-CNT/GCE. The synthesis of the α-Fe2O3-CNT nanocomposite was achieved through a simple and cost-effective hydrothermal process. Morphological and chemical characterization were conducted using scanning electron microscopy (SEM), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). The presence of the α-Fe2O3-CNT film on the GCE surface resulted in an enhanced electrochemical response to E2, preventing electrode surface fouling and mitigating the decrease in peak current intensity during E2 oxidation. These outcomes substantiate the rationale behind the GCE modification. After the optimization of experimental conditions, E2 was determined by the square wave voltammetry technique using 0.1 mol L-1 KCl solution (pH = 7.0) with 20% ethanol as a supporting electrolyte. A linear concentration range of 5.0-100.0 nmol L-1 and a low limit of detection of 4.4 nmol L-1 were obtained. The electroanalytical method using α-Fe2O3-CNT/GCE was applied for E2 determination in pharmaceutical, lake water, and synthetic urine samples. The obtained results were attested by recovery tests and by high-performance liquid chromatography as a comparative technique at a 95% confidence level. Thus, the developed electrochemical sensor is simple and fast to obtain, presents high accuracy, and is viable for determining E2 in routine analysis.

25-Hydroxy vitamin D3 electrochemical biosensor mediated by a truncated aptamer and CuCo2O4/N-CNTs

The measurement of serum 25-hydroxyvitamin D3 (25(OH)D3) levels at the clinic is essential because of its significant role in immune function and bone metabolism as well as the relationship between its deficiency and diseases such as neurodegenerative, depression, cancer, diabetes, and cardiovascular diseases. This study describes a novel electrochemical aptasensor based on a rationally truncated aptamer for sensitive, selective and low-cost quantification of 25(OH)D3. The aptasensor contains a glassy carbon electrode modified with CuCo2O4/N-CNTs nanocomposite and an engineered aptamer. Three newaptamers(VDBA14-23, VDBA14-27, and VDBA14-35) were designed via truncation of the previously selected DNA aptamer (VDBA14, 56-mer). The sensitivity and selectivity of VDBA14 and new truncated aptamers toward 25(OH)D3 were studied through the differential pulse voltammetry technique. Introducing 25(OH)D3 changes the flexibility and conformation of the aptemers and the detection strategy is done based on the peak current intensity of the redox marker [Fe(CN)6]3−/4−. In the DPV tests, the sensors built with the probable G-quadruplex VDBA14-35 aptamer showed improved sensitivity and specificity toward 25(OH)D3 than the parent VDBA14. Under optimized experimental conditions, the aptasensor response decreases with increasing the concentration of 25(OH)D3 and is linear with the logarithm of 25(OH)D3 concentration in the range from 1 × 10−13 to 1 × 10−6 M. The detection limit of the VDBA14-35/CuCo2O4/N-CNTs/GCE sensing is 0.063 pM (based on 3Sb/m). The fabricated aptasensor is simple, low-cost, selective, and sensitive. This sensor would be of great benefit for the clinical diagnosis of 25(OH)D3.

Photoelectrocatalytic Detection and Degradation Studies of a Hazardous Textile Dye Safranin T.

Herein, we report an electrochemical scaffold consisting of functionalized multiwalled carbon nanotubes (COOH-fMWCNTs) and iron-doped zinc oxide nanoparticles (Fe-ZnO) for the detection of a hazardous textile dye safranin T (ST) and monitoring of its photocatalytic degradation. Prior to the detection and degradation analysis, Fe-ZnO NPs were synthesized by the sol-gel method and characterized by a number of structural and morphological techniques. The carboxyl moiety of COOH-fMWCNTs possessing a strong affinity for the amino functionality of ST led to significant enhancement of the current response at the designed electrochemical platform, whereas the electrocatalytic role, surface area enhancement, and the provision of binding sites of Fe-ZnO led to a further increase in the peak current intensity of ST. Electrochemical impedance spectroscopy showed that the sensing scaffold made of the glassy carbon electrode modified with COOH-fMWCNTs and Fe-ZnO efficiently transfers charge between the transducer and the redox probe. Under optimized conditions, the developed sensor showed a 2.3 nM limit of detection for ST. Moreover, recovery experiments and anti-interference tests qualified the sensing platform for practical applications. The dye was photocatalytically degraded using Fe-ZnO NPs up to 99% in 60 min with a rate constant of 0.068 min-1. The designed sensor was used to probe the degradation kinetics of the target dye, and the results were found consistent with the findings obtained from electronic absorption method. To the best of our knowledge, the present work is the first approach for the efficient detection and almost absolute degradation of ST.

The propagation characteristics of the return-stroke electric wave in consideration of corona sheath

The propagation characteristics of the return-stroke current wave along the channel are an important issue in lightning research. The temperature, electrical conductivity and radius of lightning dart‑leader channels were calculated based on spectral diagnosis. Using them as initial parameters the dispersion equation for electric wave propagating along the return-stroke channel in a wide angular frequency range was solved numerically. The dispersion relations for the electric wave with and without considering the corona sheath effect were investigated. The results showed that both the propagation velocity and amplitude of electric wave decay along the channel, and the high frequency components decay faster. The corona sheath hastens the attenuation of the electric wave. The peak current intensity is closely related to the physical characteristics of the leader channel and determines the propagation velocity and amplitude attenuation of electric wave. Inferred from the attenuation characteristics of the wave, the variation of the current intensity along the channel is mainly determined by the different attenuation rate of the harmonic components with different frequencies during the transmission process.

Silver Nanoparticle-Embedded Conductive Hydrogels for Electrochemical Sensing of Hydroquinone.

In this work, a conductive hydrogel was successfully synthesized, taking advantage of the high number density of active amino and hydroxyl groups in carboxymethyl chitosan and sodium carboxymethyl cellulose. These biopolymers were effectively coupled via hydrogen bonding with the nitrogen atoms of the heterocyclic rings of conductive polypyrrole. The inclusion of another biobased polymer, sodium lignosulfonate (LS), was effective to achieve highly efficient adsorption and in-situ reduction of silver ions, leading to silver nanoparticles that were embedded in the hydrogel network and used to further improve the electro-catalytic efficiency of the system. Doping of the system in the pre-gelled state led to hydrogels that could be easily attached to the electrodes. The as-prepared silver nanoparticle-embedded conductive hydrogel electrode exhibited excellent electro-catalytic activity towards hydroquinone (HQ) present in a buffer solution. At the optimum conditions, the oxidation current density peak of HQ was linear over the 0.1-100 μM concentration range, with a detection limit as low as 0.12 μM (signal-to-noise of 3). The relative standard deviation of the anodic peak current intensity was 1.37% for eight different electrodes. After one week of storage in a 0.1 M Tris-HCl buffer solution at 4 °C, the anodic peak current intensity was 93.4% of the initial current intensity. In addition, this sensor showed no interference activity, while the addition of 30 μM CC, RS, or 1 mM of different inorganic ions does not have a significant impact on the test results, enabling HQ quantification in actual water samples.

Reduced graphene oxide supported Fe2B as robust catalysts for oxygen reduction reaction

Transition metal borides have great potential to be low-cost, high-performance catalysts for novel energies despite the synthesis is rather difficult. In this paper, the reduced graphene oxide (rGO) supported iron boride (Fe2B/rGO) based catalysts are synthesized by a facile reduction method. The successful synthesis of Fe2B is confirmed by X-ray diffraction, scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photo-electron spectroscopy (XPS) and other tests. HRTEM tests showed that the constructed Fe2B was embedded in the rGO, where B played the role of coordination atoms which could regulate the electronic structure of the catalysts and improve the catalytic performance towards oxygen reduction reaction (ORR). The electrochemistry tests showed that the peak current intensity of the Fe2B/rGO catalyzed ORR could be reached up to 7.6 mA/cm2, which surpassed that of the Pt/C (20 wt%) catalyst. The current intensity can be kept at 82.47% after continuous running 20,000 s, which is higher than the Pt/C catalyst (79.4%). The onset potential reaches up to 0.95 V, which is only 0.06 V lower than that of Pt/C (20 wt%) catalyst. Both RDE and RRDE tests confirmed that the Fe2B/rGO catalyzed ORR major happed through 4-electron pathway. The redistributed electron between iron and boron atoms promoted the happening of ORR on Fe2B/rGO catalysts. The results of this work provide a novel way to develop high performance transition metal boride based catalysts for ORR.

Research on performance of ionization chamber used in medical laser proton accelerator based on Garfield++

Gas ionization chamber has the advantage of accurate and reliable measurement data, which is widely used in beam current monitoring of proton and heavy ion beam therapy systems. According to the characteristics of the proton beam signal of the laser accelerator, because of its ultra-high peak current intensity, the peak current intensity of the beam generated by the traditional accelerator is much higher than that of the traditional accelerator. The gas ionization chamber cannot measure the proton beam with this characteristic, and the incident laser proton beam is likely to cause signal saturation and distortion in the gas ionization chamber. Therefore, it is necessary to improve the physical design of the gas ionization chamber and the supporting electronic system to improve the detection technology of the gas ionization chamber dedicated to the ion beam generated by the laser acceleration. In this paper, the physical design of the gas ionization chamber is optimized to avoid signal saturation in the gas ionization chamber while measuring the laser proton beam signal. With the method of modeling and simulation analysis of the gas ionization chamber based on the Garfield++, the optimal value is given in three aspects: the type selection of the gas medium, the gas pressure setting and the setting of the voltage of the gas ionization chamber in order to optimize the measurement signal saturation phenomenon caused by the large transient beam current intensity, and bring theoretical basis and guiding significance to the actual experimental operation. The research concludes that when helium is selected as the gas medium of the gas ionization chamber, the signal saturation can be effectively reduced; when the integration time of the electronic system of the gas ionization chamber is 500 ns, and the current measurement range is ±16 μA in actual, the optimized gas pressure should be set lower than 540 Torr and the voltage value lower than 300 V to match the electronic measuring range of the gas ionization chamber while detecting the current signal; when the signal detected is the integrated charge, the voltage setting of the gas ionization chamber has nearly nothing to do with the signal collected, but to adjust the gas pressure in the gas ionization chamber to optimize the final data.

Chemical Sensors Based on Molecularly Imprinted Polymers Can Determine Drug Release Kinetics from Nanocarriers without Filtration, Centrifugation, and Dialysis Steps.

With the development of drug delivery systems, the use of nanomaterials for slow, targeted, and effective drug release has grown significantly. To ensure the quality of performance, it is essential to obtain drug release profiles from therapeutic nanoparticles prior to in vivo testing. Typically, the methods of monitoring the drug release profile from nanoparticle drug delivery systems include one or more filtration, separation, and sampling steps, with or without membrane, which cause several systematic errors and make the process time-consuming. Here, the release rate of doxorubicin as a model drug from liposome as a nanocarrier was determined via highly selective binding of released doxorubicin to the doxorubicin-imprinted electropolymerized polypyrrole as a molecularly imprinted polymer (MIP). Incubation of the MIP-modified substrate with imprinted cavities complementary to doxorubicin molecules in the releasing medium leads to the binding of released doxorubicin molecules to cavities. The drug trapped in the cavities is determined by one of the analytical methods depending on its signaling properties. In this work, due to the favorable electrochemical properties of doxorubicin, the voltammetry method was used for quantitative analysis of released doxorubicin. The voltammetric oxidation peak current intensity of doxorubicin on the surface of the electrode was enhanced by increasing the release time. This membranelle platform allows fast, reliable, and simple monitoring of drug release profiles without any sample preparation, filtration, and centrifugation in buffer and blood serum samples.

Evaluation of voltametric profiles for quantitative estimation of sigma phase (σ) content in duplex stainless steel UNS S31803: an ohmic and layers porous resistance models (LPRM) analysis

The voltammetric profile parameters of potential and peak current intensity, for different scan rates were obtained for heat treated duplex stainless-steel samples. The Ohmic and Layer Porous Resistance models were considered for quantitative estimation of deleterious phase surface content (sigma phase). A 4 mol L-1 KOH selective solution and a specially designed electrolytic cell were used. The observed linear slope for vs and Ip vs linearity profiles are in accordance with the considered LPR Model. The parameter profile of peak potential (), with the square root of the scan rate (1mV s-1, 2 mV s-1, 5 mV s-1, 7 mV s-1 and 10 mV s-1.), suggests the growth of a film rich in Fe and Cr content that could be correlated to the sigma phase level with the dependence of on scan rate been considered a better parameter, than peak current, for detect small levels of sigma phase for a specific scan rate. The non-dependence of from surface area, make it a more feasible parameter for a lower sigma phase level quantitative analysis.

Arylene Diimide Derivatives as Anolyte Materials with Two-Electron Storage for Ultrastable Neutral Aqueous Organic Redox Flow Batteries

Arylene Diimide Derivatives as Anolyte Materials with Two-Electron Storage for Ultrastable Neutral Aqueous Organic Redox Flow Batteries

A Low-Cost Electrochemical Method for the Determination of Sulfadiazine in Aquaculture Wastewater.

As the concept of green development spreads worldwide, environmental protection awareness for production and life has been continuously strengthened. Antibiotic residues in aquaculture wastewaters aggravate environmental pollution and threaten human health. Therefore, the detection of residual antibiotics in wastewater is crucial. In this paper, a new, simple, and low-cost method based on the glassy carbon electrode electrochemical sensor for the detection of sulfadiazine in aquaculture wastewater was developed without using complex materials to modify the electrode surface, to detect sulfadiazine which electrochemically oxidizes directly. The electrochemical performance of the sensor was studied and optimized with differential pulse voltammetry and cyclic voltammetry in the three-electrode system. The optimal electrolyte was acetic acid-sodium acetate buffer, and the optimal pH was 4.0. Finally, based on the optimized conditions, the newly established method showed satisfactory results for detecting sulfadiazine in aquaculture wastewater. The concentration of sulfadiazine and the peak current intensity showed a linear relationship in the range of 20 to 300 μmol/L, and the limit of detection was 6.14 μmol/L, the recovery rate of standard addition was 87-95%, with satisfactory reproducibility and low interference.