Wave Voltammetry Research Articles

Multiplex electrochemical aptasensor for the simultaneous detection of linomycin and neomycin antibiotics

The escalating use of antibiotics across diverse sectors, including human healthcare, agriculture, and livestock, has led to their pervasive presence in the environment, raising concerns about their impact on ecosystems and human health. Traditional detection methods, reliant on high-performance liquid chromatography and immuno-assays, face challenges of complexity, cross-reactivity, and limited specificity. Aptamer-based biosensors offer a promising alternative, leveraging the specificity, stability, and cost-effectiveness of aptamers. Herein, we present a novel dual-screen-printed carbon electrode (SPCE) biosensor, modified with a nanocomposite of gold nanoparticles (AuNPs) and carbon nanofibers (CNFs), for the label-free electrochemical detection of lincomycin and neomycin antibiotics. Lincomycin and neomycin, two antibiotics of environmental concern due to their widespread usage and potential ecological impact, were simultaneously detected using square wave voltammetry. The aptasensors showed high sensitivity with detection limits of 0.02 pg/mL and 0.035 pg/mL for lincomycin and neomycin, respectively. The developed biosensor exhibited high selectivity and reproducibility in detecting both antibiotics. This multiplex biosensing platform offers a promising strategy for efficient and cost-effective monitoring of antibiotic residues in environmental samples, addressing the critical need for robust detection methods in environmental monitoring and public health surveillance.

Dual Electrochemical Methods for Determination of Anesthetic Procaine

Procaine belongs to a type of medicine in which excessive dosage form creates cardiac problems and many allergenic reactions. Thus, continuous monitoring of this drug and its metabolite is crucial for sustainable health management during treatment. In this study, electrochemical techniques such as square wave voltammetry (SWV) and differential pulse polarography (DPP) are utilized for assaying procaine amounts in standard and pharmaceutical formulations. In SWV, the reduction of diazotized procaine gives a reduction peak at −0.05 V which is directly proportional with procaine hydrochloride concentration, whereas in DPP, the interaction of the drug with lead cation at −0.4 V is followed by the decrease in peak current of the lead cation reduction peak, which is directly proportional with the concentration of the drug. Both methods indicate high accuracy, sensitivity and precision. Linear concentration ranges of both methods are 0.0999–5.996 × 10-7 M for SWV and 0.1999–5.996 × 10-7 M for DPP. The limit of detection (LOD) and limit of quantification (LOQ) are calculated for both SWV and DPP techniques, and found that LOD equals 1.984 × 10-9 M and LOQ equals 6.611 × 10-9 M for SWV, while for (DPP) LOD and LOQ were found to be 3.519 × 10-9 M and 1.173 × 10-8 M, respectively.

Green electrochemical sensor based on ZnO@α-Fe2O3 NPs modified carbon paste electrode for sensitive voltammetric determination of the FDA-approved Anti-COVID-19 medication baricitinib

In this study, we developed an electrochemical sensor for the sensitive voltammetric determination of Baricitinib (BCT), a recently FDA-approved medication for curing COVID-19. Voltammetric measurements were employed using a carbon paste electrode modified with zinc oxide and iron oxide nanoparticles (ZnO/α-Fe2O3-NPs/CPE). The composition of the fabricated electrode was optimized, and the best sensitivity was achieved by utilizing 5% of ZnO/α-Fe2O3-NPs, which maximized the electroactive surface area. The final optimized electrode was electrochemically and physicochemically characterized by exploiting the following techniques: X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS). All experimental parameters, including the pH and scan rate, have been studied and optimized. The proposed sensor was successfully employed for BCT analysis by square wave voltammetry (SWV), and the attained linear dynamic range was (8.0 × 10−8 – 1.0 × 10−6 mol L−1), and the estimated limit of detection (LOD) and limit of quantitation (LOQ) were 1.799 × 10−8 mol L−1 and 5.453 × 10−8 mol L−1, respectively. The suggested electrochemical methodology was effectively utilized to determine BCT with satisfactory percentage recoveries in pharmaceutical preparation (99.69% ± 0.73) and human plasma samples. The developed approach underwent validation and was determined to be reproducible (RSD = 0.75%) and accurate (99.68% ± 0.76) following the ICH recommendations. The greenness of the established electrochemical protocol was assessed utilizing the Analytical Eco-Scale and Analytical GREEnness Metric Approach (AGREE).

Enhanced electrocatalytic activity of hafnium doped tungsten oxide (Hf-WO3) for ultrasensitive detection of nonsteroidal anti-inflammatory drug

Efficient hafnium-doped tungsten oxide nanoparticles (Hf-WO3) were developed by hydrothermal approach and characterization was carried out by X-ray diffraction pattern (XRD), transmission electron microscopy (TEM), high resolution-transmission electron microscopy (HR-TEM), scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) techniques. Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques were employed to assess the electrochemical response of the fabricated carbon paste electrodes (CPE) for the analysis of mefenamic acid (MA). The objective of this work is to develop and optimize parameters to enhance the selectivity and sensitivity of Hf-WO3 modified sensor for the trace-level detection of MA, addressing its critical importance in both pharmaceutical and environmental analysis. The Hf-WO3 predominantly showed a monoclinic phase with some hexagonal peaks, confirming its good crystallinity and 1-D structure, which enhances charge transport and catalytic sites. XPS analysis confirmed the formation of pure Hf-WO3 by showing distinct W and Hf peaks and verifying their valences: W in the +6 state and Hf in the +4 state. CV showed that the Hf-WO3/CPE greatly enhances the electrochemical oxidation of MA compared to unmodified and tungsten oxide-modified electrodes, with a six-fold increase in peak current and notable redox activity attributed to improved surface properties and charge transfer efficiency. Under optimum experimental conditions, the Hf-WO3/CPE exhibits a low limit of detection (LOD) of 3.94 nM with dynamic concentration linearity ranging from 0.01 to 100.0 μM with good sensitivity of 1.74 μAμM−1cm−2. Furthermore, the Hf-WO3/CPE was employed in real-time analysis of MA in spiked urine samples and pharmaceutical tablet samples, which showed satisfactory recovery results ⁓ 98 %. Moreover, the electrode showed good stability over multiple measurements, and these results demonstrate that Hf-WO3/CPE is a promising sensor for MA detection.

Voltammetric Sensor Based on Titania Nanoparticles Synthesized with Aloe vera Extract for the Quantification of Dithiophosphates in Industrial and Environmental Samples

In this work, TiO2 spherical nanoparticles with a mean diameter of 10.08 nm (SD = 4.54 nm) were synthesized using Aloe vera extract. Rutile, brookite, and anatase crystalline phases were identified. The surface morphology of a carbon paste electrode does not change in the presence of nanoparticles; however, the surface chemical composition does. The voltammetric response to dicresyl dithiophosphate was higher when the electrode was modified with TiO2 nanoparticles. After an electrochemical response study from pH 1.0 to 12.0, pH 7.0 was selected for the electroanalysis. The electroactive area of the modified sensor was 0.036 cm2, while it was 0.026 cm2 for the bare electrode. The oxidation process showed mixed adsorption-diffusion control. The charge transfer resistance of the modified sensor (530.1 Ω, SD = 4.08 Ω) was much lower than that of the bare electrode (4298 Ω, SD = 8.53 Ω). The linear quantitative range by square wave voltammetry was from 5 to 150 μmol/L, with a limit of detection of 1.89 μmol/L and a limit of quantification of 6.26 μmol/L under optimal pulse parameters of 50 Hz frequency, 1 mV step potential, and 25 mV pulse amplitude. The sensor response was repeatable and reproducible over 30 days. The results on real flotation and synthetically contaminated soil samples were statistically equivalent to those obtained by UV-vis spectrophotometry. A dithiocarbamate showed an interfering effect on the sensor response to dithiophosphate.

Dual electrochemical detection of leucovorin and its metabolite 5-methyltetrahydrofolic acid

Current healthcare trends focus on personalised precision medicine, which customises treatment based on individual responses to both diseases and therapeutic interventions. This marks a departure from a “one size fits all” approach towards a more sophisticated strategy. However, notwithstanding progress in the theoretical knowledge for personalised precision approaches, resource constraints impede their implementation. Monitoring drug therapies is vital for the advancement of precision medicine, alongside drug development and targeted treatment strategies. This study presents the potential of electrochemical approaches including square wave voltammetry (SWV) as a proof-of-concept for the simultaneous monitoring of circulating concentrations of 5-methyltetrahydrofolate (5-MTHF) and leucovorin calcium (LV) within biological matrices. An easy-to-use and portable sensor has been developed for the detection of 5-MTHF and LV at therapeutically relevant concentrations without prior sample preparation. The sensor was successfully tested in artificial urine and human pooled serum, demonstrating its efficacy in diverse biological matrices. This approach successfully illustrated the dual detection of LV and 5-MTHF over the linear range 0 to 10 µM which is within the therapeutically relevant range for both within urine. The developed sensor exemplifies the potential of electrochemical sensors as point-of-care devices. Its rapid time to result and elimination of time-consuming sample preparation improve usability for clinicians, broadening the application of electrochemical sensors in clinical settings. This dual monitoring approach offers significant contributions to the evolution of precision medicine by providing real-time, accurate drug monitoring capabilities.

Aptasensing of rivaroxaban in human plasma using KCC-1-NH-CS2 modified conductive nano-ink: A new biosensor

An innovative paper-based electrochemical aptasensor has been developed for the detection of Rivaroxaban (RIV) in human plasma samples. The sensor is fabricated using a novel prob by encapsulating aptamer-aminated on dendritic fibrous nano-silica (KCC-1-NH-CS2) particles. The prob is then immobilized on the functionalized silver nano-ink electrode.. The resulting redox reaction on the prob was subsequently evaluated using square wave voltammetry, differential pulse voltammetry, and chronoamperometry. Under optimized condition and using a label-free strategy, the aptasensor exhibited suitable sensitivity and specificity for detecting RIV with a linear range of 10 to 1000 nM and a lower limit of quantification (LLOQ) of 10 nM. The engineered aptasensing platform shows great potential for the fabrication of other cost-effective, sensitive, and portable biosensors for the pharmaceutical and biomedical analysis.

Bimetallic Fe/Co-MOF dispersed in a PVA/chitosan multi-matrix hydrogel as a flexible sensor for the detection of lactic acid in sweat samples.

Anovel bimetallic Fe/Co-metal-organic framework (MOF) hydrogel-based wearable sweat sensorwas developed. Morphological and structural analysis of the hydrogel shows uniformly sized spines and spindle-shaped particles of the Fe/Co-MOF, and it has a high surface area (132.306 m2g-1) and porosity (0.059 cm3g-1) as confirmed by Brunauer-Emmett-Teller (BET) studies. The integration of the bimetallic MOF into a polyvinyl alcohol/chitosan (PVA/CS)-mixed matrix resulted in a multiple network hydrogel. The optimisation study investigated the effects of different pH of the PBS electrolyte, scan rates, and accumulation time in voltammetry. The electrochemical methods such as cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) provided information on the redox behaviour, electrochemical stability, and catalytic activity of the hydrogel. The sensor demonstrates a wide linear detection range from 0.05µM to 100mM, a superior sensitivity of 0.02mAmM-1cm-2, and a lower limit of detection of 0.01µM . Active sites distributed over the hydrogel surface, specifically Fe2+ and Co2+ within the MOF structure, catalyse the oxidation of L-lactic acid, resulting in electron transfer and the formation of pyruvic acid. Notably, the fabricated sensor exhibits high selectivity, effectively discriminating against interfering species such as uric acid, ascorbic acid, glucose, urea, dopamine, NaCl, and CaCl2. Real-time analysis conducted in a simulated sweat sample via the standard addition method resulted in good recovery percentages of a minimum of 98%. The work presented here is a versatile and simple platform for point-of-care testing, especially for athletes and military personnel.

Electrochemical Analysis of Key Anticancer Herbal Drugs: Progress and Innovations in Emodin, Rutin, Berberine, Shikonin, and Sophoridine

Background: Anticancer herbal drugs have gained significant attention in pharmaceutical research due to their complex chemical profiles and multifaceted therapeutic effects. Electrochemical analysis has emerged as a powerful tool for studying these compounds, offering unique insights into their behavior and properties. Methods: This review examines recent advances in the electrochemical analysis of five key anticancer herbal drugs: emodin, rutin, berberine, shikonin, and sophoridine. Various electrochemical techniques, including cyclic voltammetry, differential pulse voltammetry, and square wave voltammetry, are discussed in relation to their application in detecting and characterizing these compounds. Results: Significant progress has been made in developing highly sensitive and selective electrochemical sensors for these herbal drugs. Nanomaterial-modified electrodes have consistently improved detection limits and expanded linear ranges. Compound-specific innovations in electrode modifications and measurement techniques have been tailored to the unique electrochemical properties of each drug. Conclusion: Electrochemical analysis of anticancer herbal drugs has advanced substantially, offering powerful tools for studying and utilizing these compounds in cancer research and treatment. Future directions include the development of multi-analyte sensors, integration with microfluidic technologies, and application of artificial intelligence for data analysis. Challenges remain in improving the stability of modified electrodes and standardizing protocols for sample preparation and analysis.

Electrochemical biosensing of Acinetobacter baumannii gene using chitosan-gold composite modified electrode

In this study, a novel electrochemical biosensor was developed for the sensitive and selective detection of the Acinetobacter baumannii gene sequence. The biosensor was created by immobilizing a capture probe specific to the A. baumannii gene on the surface of chitosan-gold modified pencil graphite electrodes. Following solid-state hybridization on the Chit-Au/PGE surface, the target DNA sequence of the A. baumannii was detected by measuring the guanine signal using square wave voltammetry (SWV). All experimental parameters impacting sensor response are examined in order to improve hybridization efficacy, and the electrochemical biosensor's performance. The limit of detection (LOD) for the A. baumannii gene sequence was calculated and found to be 1.93 nM. Three different non-complementary DNA sequences were used to evaluate the assay selectivity, but no interference effect was obtained. Additionally, the potential applicability of the biosensor to real samples was tested in artificial serum media. The suggested electrochemical test procedure is simple, approachable, and quick, making it a convenient approach for the screening of DNA sequence.

Detection of the stimulant clobenzorex using voltammetry and screen-printed electrodes: A simple and fast screening method for application in seized samples and oral fluid of drivers

Clobenzorex (CBZ) is a stimulant drug, recognized for its anorectic potential, legally used in some countries for obesity treatment. However, CBZ is banned in much of the world and has been often used illegally by drivers needing to stay alert for extended periods. Therefore, the rapid identification of CBZ in forensic samples is of paramount importance for public health and safety. In this context, we introduce an innovative electroanalytical screening method for detecting CBZ in seized tablet samples and human oral fluid using voltammetry with a graphite screen-printed electrode (SPE-Gr). The electrochemical detection was optimized in phosphate buffer solution (0.1 mol L−1, pH 7.0) using square wave voltammetry (SWV). The SPE-Gr combined with SWV exhibited a good stability of the electrochemical responses for CBZ detection, with a relative standard deviation of less than 5% across different days (N = 5) and using different SPEs (N = 3). A linear detection range of 2.5–100.0 μmol/L (R2 = 0.992) was achieved, with a low limit of detection (LOD) of 0.32 μmol L−1. Interference studies with other illicit drugs and adulterants confirmed the selectivity of the proposed method for CBZ detection. In addition, the presence of CBZ in seized tablet samples and authentic oral fluids, collected from drivers, was detected and identified using the proposed method, which results were also confirmed by HPLC-MS. Consequently, integrating SPE-Gr with SWV offers a reliable, rapid, sensitive, selective, reproducible, and direct approach for the preliminary qualitative and quantitative analysis of CBZ in forensic contexts. Furthermore, the proposed method provides an efficient oral fluid test for CBZ screening in drivers under the influence of drugs.

Electrochemical sensor for the analysis of 5-hydroxymethylcytosine in the presence of cytosine using pencil graphite electrode

In recent years, important efforts have been made to elucidate the mechanisms of epigenetic regulation, and one of the most studied epigenetic modifications was DNA methylation/demethylation. In this study, the voltammetric behaviour of 5-hydroxymethylcytosine was studied in the pH range of 2.00–11.00 using pencil graphite electrodes by differential pulse and square wave voltammetry. The effect of buffer solutions, scan rate, square wave voltammetry parameters, and stripping conditions on the voltammetric responses of 5-hydroxymethylcytosine were performed. The electrochemical oxidation process of 5-hydroxymethylcytosine on the pencil graphite electrode was realized under adsorption control. In human urine, by square wave stripping voltammetry, 5-hydroxymethylcytosine was quantified in a concentration range of 1.00 × 10−5 M-2.00 × 10−4 M. The proposed method was tested in the presence of cytosine in human urine. The recovery value of 5-hydroxymethylcytosine was found to be 99.57 %.

Investigation on the reaction progress of titanium and lead chloride in NaCl-KCl melt

The in-situ preparation of NaCl-KCl-TiClx molten salt electrolyte was investigated by replacement of PbCl2 and Ti in a NaCl-KCl melt at 750 ℃. The reaction progress of PbCl2(3.38 wt.%) with excess Ti was monitored in real-time by a series of electrochemical techniques such as cyclic voltammetry, square wave voltammetry, and open circuit chronopotentiometry. The thermodynamic calculation and electrochemical test results show that titanium ions are mainly generated in the form of Ti(III). The redox peak current of Pb(II) decreases rapidly and drops to below the detection limit of the electrochemical tests after 275 min. Simultaneously, the reduction peak current of Ti(III) increases rapidly from 0 to 75min, and reaches to the maximum value until 275 min. At this time, the replacement reaction has been completed, and the NaCl-KCl-TiClx(2≤x≤4) molten salt is obtained finally. Ti-Pb alloy was obtained by depositing at -1.0 V(vs. Ag/AgCl) for 30 min during the replacement process. Lead by-product of the replacement reaction was precipitated and collected. Electrolytic refining was carried out successfully using the NaCl-KCl-TiClx molten salt electrolyte prepared as described above. The results demonstrated that a stable NaCl-KCl-TiClx molten salt electrolyte can be obtained by the present method. The study provides a new thinking for the preparation of molten salt electrolyte containing titanium ions, and also provides theoretical references for the electrolytic refining of titanium and the preparation of titanium alloys by electrodeposition.

Fe-doped WO3-Modified sensor for the improved electrochemical detection of curcumin

In this study, an iron-doped tungsten oxide (Fe-WO3) nanomaterialwas synthesizedand utilized to modify carbon paste electrodes for the identification of the bioactive ingredient curcumin (CUM). Turmeric contains a bioactive compound called curcumin, which is yellow and has various potential biological applications, such as being an anti-carcinogenic, anti-inflammatory, and antioxidant agent. The Fe-WO3 nanomaterial underwent characterization through SEM, XRD, and EDS techniques. The electrochemical performance of CUM was inquired using square wave and cyclic voltammetry methods. During catalytic oxidation, the Fe-WO3 working electrode assembly showed faster electron transport than the bare CPE. Investigations havebeen conductedinto the kinetics of oxidation, and the developed sensor demonstrated an excellent linear detection range (5 μM to 60 μM), a decreased limit of detection (6.2 × 10−8 M), and a limit of quantification under optimal conditions (20.7 × 10−8 M).The numbers of electrons transmitted, the heterogeneous rate constant, the electron transfer coefficient, and the electrochemical oxidation were all measured. The results from the examination of CUM in actual samples using the devised Fe-doped WO3 modified electrode were good. Additionally, it showed a considerable increase in the curcumin peak current concerning responsively, specificity, and reliability for curcumin analysis.

Enhanced production of bioethanol through supercritical carbon dioxide-mediated pretreatment and saccharification of dewaxed bagasse

The pretreatment and saccharification of dewaxed bagasse (DWB) has been investigated under various reaction conditions ranging 2000 to 3200 psi, at 70 ± 1 °C in supercritical carbon dioxide (SCC). This has been in attempt to transform the DWB into fermentable sugar and bioethanol in high yields. The effect of SCC mediated pretreatment and enzymatic hydrolysis on structural and morphological alterations in DWB has been ascertained through diverse analytical methods. The sugar has been released through cellulase (40 FPU/mL) mediated enzymatic hydrolysis of pretreated DWB in sodium acetate buffer (pH 4.7) within 1 h at SCC 2800 psi, 70 ± 1 °C. The released sugar was subsequently fermented in the presence of yeast (Saccharomyces crevices, 135 CFU) at 28 ± 1 °C over 72 h to afford the bioethanol. The SCC mediated process conducted in acetic acid:water media (1:1) at 2800 psi, 70 ± 1 °C over 6 h has afforded the pretreated DWB with maximum yield towards the production of fermentable sugar and bioethanol. The production of fermentable sugar and bioethanol has been electrochemically estimated through cyclic voltammetry (CV) and square wave voltammetry (SWV) over glassy carbon electrode in KOH (0.1 M). The electrochemical methods were found selective and in close agreement for estimation of the yields (%) of fermentable sugars and bioethanol. The yield (%) of fermentable sugar estimated from CV and SWV were 80.10 ± 5.34 and 79.00 ± 5.09 respectively. Whereas the yield (%) of bioethanol estimated from CV and SWV were 81.30 ± 2.78% and 78.6 ± 1.25% respectively. Present investigation delivers a SCC mediated green and sustainable method of pretreatment of DWB to afford the enhanced saccharification, to produce bioethanol in high yields.

A cost-effective method for the sensitive detection of levofloxacin using a 3D composite electrode composed of nail polish, graphite and aluminium oxide.

The potential impact on human health and the environment has spurred significant interest in detecting and quantifying pharmaceutical compounds across various matrices, from environmental to biological samples. Here, we present an electrochemical approach for determining levofloxacin in drug, synthetic urine, water, and breast milk samples. An affordable sensor was constructed using 3D printing and composite material based on nail polish, graphite, and aluminum oxide. The conductive composite material was characterized spectroscopically, electrochemically, and by imaging techniques. Subsequently, an electrochemical method based on square wave voltammetry was optimized and applied. The method exhibited good sensitivity (5.11 ± 0.0912 μA L μmol-1 cm-2) and enhanced stability (RSD = 7.2%), with electrochemical responses correlating with the concentration of levofloxacin in the samples tested, yielding recovery values in the range of 98 to 111%. The developed method demonstrated a robust linear working range from 2 to 100 μmol L-1 and a nanomolar detection limit of 128 nmol L-1, rendering it suitable for quantitative analysis. The sensor also shows promise as a platform for the sensitive detection of pharmaceutical compounds, contributing to greater safety and sustainability in these domains.

A novel nanovoltammetric sensor design for the sensitive determination of caffeic acid in Turkish coffee

Caffeic acid has anti-inflammatory, antibacterial, anticarcinogenic and immunomodulatory properties as well as antioxidant properties. Therefore, precise determination of the quantity of this acid is important for analytical and therapeutic interests as well as for the safety and quality of food samples. This study aims to determine the amount of caffeic acid in Turkish coffee by using the square wave voltammetry technique. This method has been successfully applied for the precise determination of caffeic acid with a platform in which the glassy carbon electrode is constructed with a modifier obtained based on the synergistic effect of functionalized multi-walled carbon nanotubes with boron oxide nanoparticles. The proposed platform and method gave a quantification limit of 0.04 nM in a dynamic range of 1.0 nM ˗ 40 μM for caffeic acid and was successfully used in the Turkish coffee sample to determine caffeic acid. In addition, the results are found in line with the results obtained by UV-Vis spectrophotometry method, and the good recovery values also imply the feasibility of the platform for practical application.

Poly-methionine/graphitic carbon nitride modified screen-printed electrodes: A metal-free, bio-interface for tryptophan sensing

Tryptophan (TRP) is an essential amino acid needed for the growth and proper functioning of the human body. A balanced intake of TRP-rich food products is essential to meet the daily requirements. As both low and high levels of TRP are associated with clinical disorders, an optimum amount of TRP intake is critical. Hence, developing a method to efficiently detect TRP in food and nutritional supplements is essential. Accordingly, this study reports the electrochemical detection of TRP using poly-methionine/graphitic carbon nitride modified screen-printed electrode (gCN.Meth|SPE). To our knowledge, this study is the first attempt to decipher the electrodeposition of gCN.Meth on a conducting substrate through a systematic analysis of the electro-functionalized gCN.Meth surface using XRD, FT-IR, HR-SEM, EDX, and AFM. The synergistic benefits of both the gCN and conducting poly(methionine) resulted in augmented electrochemical performance exhibiting a pronounced TRP oxidation peak in both cyclic voltammetry (CV) and square wave voltammetry (SWV). The improved electrochemical response can be ascribed to the specific interactions between the TRP and gCN through π- π interactions and hydrogen bonding and electrostatic interaction between TRP and methionine. This facilitated interaction resulted in the electro-catalytic oxidation of TRP with a negative potential shift of 0.126 V and a 16.6-fold increase in the current response compared to unmodified SPE. The gCN.Meth|SPE exhibited a 25.12 times higher sensitivity compared to bare SPE, with a linear response in the concentration ranges of 1.0–300.0 μM and a low detection limit of 29.9 nM. The interference study further indicated that gCN.Meth-modified SPEs is highly effective for the precise and reliable detection of tryptophan in real samples.

Influence of cationic species on the electrochemical performance of quinone derivatives

Quinones exhibit considerable promise as active components in energy storage applications, owing to their high theoretical storage capacity, well-defined redox potentials, rapid reaction kinetics, structural diversity, and proficiency in cycling both protons and metal ions. In this study, six quinone derivatives underwent comprehensive electrochemical and computational analyses using TBA+, H+, Li+, K+, Na+, Ca2+, and Mg2+-based electrolytes, aiming to uncover novel cycling chemistries with organic materials. Cyclic Voltammetry (CV) and Square Wave Voltammetry (SWV) elucidated the widely recognized 2H+/2e- redox process during proton cycling, as well as the two-step 1e- redox process in the presence of other cycling ions. Additionally, it was established that the quinone formal redox potential for different cycling chemistries followed the sequence TBA+ < K+ < Na+ < Li+ < H+, and cycling of the divalent cations resulted in potentials within the same range as those observed for proton cycling. DFT calculations provided insights into how cycling ions influenced the quinone formal redox potential, attributing it to the cation's ability to accommodate a portion of the bisolate anion charge upon reduction. Cations inducing a higher quinone formal redox potential and accommodating a larger fraction of the negative charge demonstrated a greater stabilizing effect on the reduced state. This stabilizing effect exhibited a strong correlation with the ionization energies of the respective cations.

Antinociceptive, anti-inflammatory, and antioxidant effects of a flavonoid-rich phytocomplex from the leaves of Celtis iguanaea (jacq.) Sargent (Cannabaceae)

We demonstrated the antinociceptive and anti-inflammatory effects of the ethyl acetate leaf extract of Celtis iguanaea (Jacq.) Sargent (EAECi) in mice. The in vitro antioxidant activity of EAECi and its phytoconstituents was also investigated. The antinociceptive effect of EAECi is attributed to its anti-inflammatory activity, as evidenced by its anti-hyperalgesic and antiedematogenic effects. EAECi reduced polymorphonuclear cell migration, myeloperoxidase activity, pro-inflammatory cytokines (TNF-α and IL-1β), and PGE2 levels. The levels of anti-inflammatory cytokines (IL-4 and IL-10) were increased compared to the vehicle-treated groups. The overall antioxidant capacity of EAECi is noteworthy, with the Electrochemical Index determined by Differential Pulse Voltammetry being 42.7 μA/V. Concurrently, Square Wave Voltammetry revealed the reversibility of the redox process (Ep1a/Ep1c) at 0.254 V. The presence of twenty-six phytochemicals, primarily flavone aglycones, was suggested by paper-spray mass spectrometry. These findings represent a step towards validating C. iguanaea leaf extract for treating acute inflammatory conditions.