Electrolytic growth of phenyl-modified silica isoporous membrane for non-polar extraction and electrochemical detection of pentachloronitrobenzene.

A phenyl-modified silica isoporous membrane (Ph-SIM) was prepared on the indium-tin-oxide (ITO) electrode using the electrochemically assisted self-assembly (EASA) method. The resulting Ph-SIM preserved vertically ordered nanochannels while exhibiting outstanding hydrophobicity due to the incorporation of phenyl groups within the nanochannels. As a result, the Ph-SIM/ITO sensor exhibited a remarkable affinity for PCNB extraction through hydrophobic interactions, leading to high detection sensitivity. The electrochemical response showed a linear enhancement with the logarithmic concentration of PCNB ranging from 0.1 to 20.0 µM, and the limit of detection was 4.64 nM. Practical results demonstrated that the Ph-SIM/ITO sensor possessed good anti-fouling capability and robust stability, making it a promising candidate for portable detection of non-polar contaminants.

Electrobiofabrication of antibody sensor interfaces within a 3D printed device yield rapid and robust electrochemical measurements of titer and glycan structure.

We report the integration of 3D printing, electrobiofabrication, and protein engineering to create a device that enables near real-time analysis of monoclonal antibody (mAb) titer and quality. 3D printing was used to create the macroscale architecture that can control fluidic contact of a sample with multiple electrodes for replicate measurements. An analysis "chip" was configured as a "snap-in" module for connecting to a 3D printed housing containing fluidic and electronic communication systems. Electrobiofabrication was used to functionalize each electrode by the assembly of a hydrogel interface containing biomolecular recognition and capture proteins. Specifically, an electrochemical thiol oxidation is used to assemble a thiolated polyethylene glycol hydrogel, that in turn is covalently coupled to either a cysteine-tagged protein G that binds the antibody's Fc region or a lectin that binds the glycans of target mAb analytes. We first show the design, assembly, and testing of the hardware device. Then, we show the transition of a step-by-step sensing methodology (e.g., mix, incubate, wash, mix, incubate, wash, measure) into the current method where functionalization, antibody capture, and assessment are performed in situ and in parallel channels. Both titer and glycan analyses were found to be linear with antibody concentration (to 0.2 mg/L). We further found the interfaces could be reused with remarkably similar results. Because the interface assembly and use are simple, rapid, and robust, we suggest this assessment methodology will be widely applicable, including for other biomolecular process development and manufacturing environments.

Exploring the economic viability of electrochemical assessment for water contaminants with NiFe-PBA/ZIF-67 core shell modified GCE.

Zeolitic Imidazolate (metal organic) Frameworks (ZIFs) and Prussian Blue Analogues (PBAs) are promising materials in electrochemical sensing due to their unique properties. In this study, a composite material comprising NiFe-PBA and ZIF-67 was synthesized and made to form a uniform layer onto a glassy carbon electrode (GCE) to enhance electrochemical performance for furazolidone (FZD) detection. The synthesized NiFe-PBA/ZIF-67 composite exhibited excellent sensitivity, selectivity, and stability towards FZD detection, with a low limit of detection (LOD). The electrochemical behaviour of FZD on the NiFe-PBA/ZIF-67/GCE electrode was investigated, revealing a diffusion-controlled process. Differential pulse voltammetry (DPV) analysis demonstrated the synergetic effect of the PBA/MOF core-shell structure in enhancing FZD electro-reduction. The sensor exhibited exceptional LOD of 0.007 µM. Selectivity studies confirmed the sensor's ability to distinguish FZD from potential interferents. Extensive evaluations demonstrated the sensor's reproducibility, repeatability, and long-term stability, affirming its practical utility. Real sample analysis further validated the sensor's excellent analytical capabilities in diverse matrices.

Fast and simple voltammetric sensing of avanafil in the pharmaceutical formulation by using unmodified boron-doped diamond electrode.

Background and purpose: Erectile dysfunction is a common issue among adult males involving difficulty in maintaining an erection, and it is often treated with fast-acting, low-side-effect drugs like avanafil (AVN), among other phosphodiesterase-5 inhibitors. Hence, developing fast, simple, and sensitive methods to detect AVN is crucial. Experimental approach: This study conducts an electroanalytical inquiry and provides a new voltammetric method for accurately analyzing AVN utilizing a boron-doped diamond (BDD) electrode without any modifications. Key results: In the Britton-Robinson buffer (BR, 0.04 mol L-1, pH 4.0), cyclic voltammetry showed a clearly defined and irreversible anodic peak at around +1.44 V relative to Ag/AgCl. The pH of the solution was shown to have an impact on the voltammetric signals of the oxidation peaks. A good linear response for AVN quantification was achieved using square-wave voltammetry. This was done in a 0.04 mol L-1 BR (pH 4.0) solution at a potential of +1.33 V (vs. Ag/AgCl). The method exhibited a wide dynamic range of 0.5 to 30.0 µg mL-1 (1.0 to 62 µmol L-1) and a low limit of detection of 0.14 µg mL-1 (0.29 µmol L-1). The method proposed demonstrated suitability for determining AVN content in pharmaceutical formulations. The accuracy of the approach was demonstrated by comparing the results obtained using the developed method with those achieved using the UV-Vis spectrometry method. Conclusion: Our method simplifies the analytical process by eliminating the need for electrode modification, reducing both time and resource requirements while enhancing overall feasibility.

A critical review of electrochemical and optical Vitamin B6 sensing: evolution of biosensor platforms based on advanced nanosystems.

Vitamin B6 (VB6) is a member of the water-soluble B vitamins which have a vital performance in nervous system operating activities. VB6 is highly demanded to maintain excellent skin and immune systems in the human body. furthermore, VB6 is tremendously substantial in the functions of some enzymes that participate in the metabolism of proteins, amino acids, etc. The deficiency of VB6 will eventuate in anemic situations and may lead to permanent injuries in the brain. moreover, recent studies disclosed that adequate Vitamin B6 in the human body can decrease the intensity of illnesses such as diabetes, stress, etc., in patients with COVID-19 infections. Thus, the detection of VB6 from real samples is crucial to control the amount of this vitamin in biological fluids and to monitor the pharmaceutical dosage quality. Various analytical approaches have been employed for the VB6 detection in biological and pharmaceutical samples. Although biosensing and sensing approaches hold several obvious advantages such as simplicity, capability for miniaturization, quick response time, etc. from other analytical methods. Hence, through the last decades, designing and fabricating biosensors with sufficient sensitivity and selectivity have been investigated by many researchers in order to detect VB6. The purpose of this review is to illustrate the importance of diverse electrochemical and optical approaches for VB6 detection. Additionally, novel VB6 detection techniques based on electrochemical, optical, and conventional methods have been considerably discussed, and compared with each other. Furthermore, a comprehensive summary of the current limitations and future challenges in VB6 analysis are explained and also create a pathway for subsequent expansions and applications.

Vitamin B₆ is an essential compound for proper function of human body.Various nanomaterial-based methods such as conational approach, electrochemical biosensing and apta-sensing analyses for Vitamin B₆ detection has been developed.Different techniques for detecting of Vitamin B₆ have been comprehensively discussed.Various electrochemical sensors fabrication and its application in Vitamin B₆ detection with nanomaterials have been assessed.The article points out the recent progress limitations, and also the upcoming tasks in the successful sensor fabrication with the functionalized nanomaterials.

Synthesis of Copper Molybdate and Its Electrochemical Sensing of Paracetamol.

Background In recent years, significant advancements have been made in various scientific sectors, particularly in healthcare and pharmaceutical research. This progress has been driven by the development of enhanced sensing materials and methodologies. Electrochemical sensing has become an important tool in detecting and analyzing drug molecules due to its high sensitivity, specificity, and rapid response times. Among various drugs, paracetamol, also known as acetaminophen, is widely used for its analgesic and antipyretic properties. Accurate detection of paracetamol is crucial due to its widespread use and potential for overdose, which can lead to severe liver damage. Copper molybdate (CuMoO4) is a transition metal oxide that has garnered attention for its excellent electrical conductivity and electrochemical stability. These properties make it a promising candidate for use in electrochemical sensors. The ability of CuMoO4 to act as a sensor material is enhanced by its unique structural and morphological characteristics, which can be tailored during synthesis. Aim This study aimed to synthesize CuMoO4 and investigate its electrochemical sensing capability for the detection of drug molecules, specifically paracetamol. Materials and method CuMoO4 was synthesized using a precipitation method that did not involve any surfactants. This approach was chosen to simplify the synthesis process and avoid potential contamination from surfactants. The morphology of the synthesized CuMoO4 nanoparticles was investigated using a field emission scanning electron microscope (FE-SEM). Energy-dispersive X-ray spectroscopy (EDX) confirmed the purity of the CuMoO4 nanomaterial. Structural analysis was performed using X-ray diffraction (XRD). To evaluate the electrochemical sensing capability of CuMoO4 for paracetamol, Differential pulse voltammetry (DPV) was employed. DPV is a sensitive electrochemical technique that can detect changes in current response corresponding to the presence of analytes. Results The synthesized CuMoO4 exhibited a rock-like structure, as revealed by FE-SEM imaging. This morphology is advantageous for electrochemical applications due to the increased surface area available for interaction with analytes. EDX confirmed the purity of the CuMoO4 nanomaterial, showing no significant impurities. XRD analysis indicated that the CuMoO4 nanoparticles were crystalline in nature, which is beneficial for consistent and reproducible electrochemical behavior. The DPV analysis demonstrated that the CuMoO4 sensor exhibited a linear increase in current response with increasing concentrations of paracetamol. This linear relationship indicates that CuMoO4 is capable of detecting paracetamol effectively, with a strong and quantifiable signal response. Conclusion The CuMoO4 nanomaterial was successfully synthesized using a simple precipitation method and was characterized by its rock-like morphology and crystalline structure. Electrochemical testing using DPV showed that CuMoO4 has excellent sensing capabilities for detecting paracetamol, with a clear and linear current response. These findings suggest that CuMoO4 is a promising electrochemical sensing material for drug detection, potentially offering a reliable and efficient method for monitoring paracetamol and possibly other pharmaceuticals in various settings.

Enhanced Enantioselective Discrimination Regulated by Achiral Ligands in Chiral Metal-Organic Frameworks.

Enantioselective recognition is a fundamental property of chiral linkers in chiral metal-organic frameworks (CMOFs). However, clarifying the efficient enantioselective discrimination tailored by achiral linkers remains challenging to explain the chiral recognition mechanism and efficiency. Here, two CMOFs ([Zn2(l-Phe)2(bpa)2]n and [Zn2(l-Phe)2(bpe)2]n) with the completely different enantioselective recognition are synthesized from different nonchiral ligands and the same chiral ligands. The enantioselective recognition of CMOF is undoubtedly related to l-Phe, which differs in the hydrogen bonding to the Trp enantiomer. However, the electrochemical signals are weak and undifferentiated. [Zn2(l-Phe)2(bpe)2]n produces a flattened coplanar conformation with the -C═C- tether in the achiral ligand. The flattened achiral bpee ligand and its surrounding chiral phenylalanine molecules interact through multiple π-π stacking and hydrogen bonding, which together create a chiral sensor that facilitates the recognition of l-Trp. However, [Zn2(l-Phe)2(bpa)2]n produces a stepped conformation due to the -C-C- tether in the achiral ligand; despite the recognition effect of bpea, the recognition is unsatisfactory. Therefore, the chiral recognition of the two CMOFs stems from the synergistic effect between chiral and achiral ligands. This work shows that nonchiral ligands are also crucial in determining enantiomeric discrimination and opens up a new avenue for designing chiral materials.

Integrating Pt nanoparticles with 3D Cu2- x Se/GO nanostructure to achieve nir-enhanced peroxidizing Nano-enzymes for dynamic monitoring the level of H2O2 during the inflammation.

The treatment of wound inflammation is intricately linked to the concentration of reactive oxygen species (ROS) in the wound microenvironment. Among these ROS, H2O2 serves as a critical signaling molecule and second messenger, necessitating the urgent need for its rapid real-time quantitative detection, as well as effective clearance, in the pursuit of effective wound inflammation treatment. Here, we exploited a sophisticated 3D Cu2- x Se/GO nanostructure-based nanonzymatic H2O2 electrochemical sensor, which is further decorated with evenly distributed Pt nanoparticles (Pt NPs) through electrodeposition. The obtained Cu2- x Se/GO@Pt/SPCE sensing electrode possesses a remarkable increase in specific surface derived from the three-dimensional surface constructed by GO nanosheets. Moreover, the localized surface plasma effect of the Cu2- x Se nanospheres enhances the separation of photogenerated electron-hole pairs between the interface of the Cu2- x Se NPs and the Pt NPs. This innovation enables near-infrared light-enhanced catalysis, significantly reducing the detection limit of the Cu2- x Se/GO@Pt/SPCE sensing electrode for H2O2 (from 1.45 µM to 0.53µM) under NIR light. Furthermore, this biosensor electrode enables in-situ real-time monitoring of H2O2 released by cells. The NIR-enhanced Cu2- x Se/GO@Pt/SPCE sensing electrode provide a simple-yet-effective method to achieve a detection of ROS (H2O2、-OH) with high sensitivity and efficiency. This innovation promises to revolutionize the field of wound inflammation treatment by providing clinicians with a powerful tool for accurate and rapid assessment of ROS levels, ultimately leading to improved patient outcomes.

Influence of Potentiostat Hardware on Electrochemical Measurements.

We describe two operating modes for the same potentiostat, where the redox processes of hydroquinone in a hydrochloric acid medium are contrasted for cyclic voltammetry (CV) as functions of a digital/staircase scan and an analogue/linear scan. Although superficially there is not much to separate the two modes of operation as an end user, differences can be seen in the voltammograms while switching between the digital and analogue modes. The effects of quantization clearly have some impact on the measurements, with the outputs between the two modes being a function of the equivalent-circuit model of the electrochemical system under investigation. Increasing scan rates when using both modes produces higher peak redox currents, with the differences between the analogue and digital modes of operation being consistent as a function of the scan rate. Differences between the CV loops between the analogue and digital modes show key differences at certain points along the scans, which can be attributed to the nature of the electrolyte affecting the charging and discharging processes and consequently changing the peak currents of the redox processes. The faradaic processes were shown to be independent of the scan rates. Simulations of the equivalent-circuit behaviour show differences in the responses to different input signals, i.e., the step and ramp responses of the system. Both the voltage and current steps and ramp responses showed the time-domain behaviour of distinct elements of the equivalent electrochemical circuit model as an approximation of the applied digital and analogue CV input signals. Ultimately, it was concluded that similar parameters between the two modes of operation available with the potentiostat would lead to different output voltammograms and, despite advances in technology, digital systems can never fully emulate a true analogue system for electrochemical applications. These observations showcase the value of having hardware capable of true analogue characteristics over digital systems.

Optimized Ammonia-Sensing Electrode with CeO2/rGO Nano-Composite Coating Synthesized by Focused Laser Ablation in Liquid.

This study investigated the synthesis of cerium oxide (CeO2) nanoparticles (NPs) and composites with reduced graphene oxide (rGO) for the enhanced electrochemical sensing of ammonia. CeO2 NPs were prepared by the focused laser ablation in liquid (LAL) method, which enabled the production of high-purity, spherical nanoparticles with a uniform dispersion and sizes under 50 nm in a short time. The effects of varying irradiation fluence and time on the nanoparticle size, production yield, and dispersion were systematically studied. The synthesized CeO2 NPs were doped with rGO to form CeO2/rGO composites, which were drop casted to modify the glassy carbon electrodes (GCE). The CeO2/rGO-GCE electrodes exhibited superior electrochemical properties compared with single-component electrodes, which demonstrated the significant potential for ammonia detection, especially at a 4 J/cm2 fluence. The CeO2/rGO composites showed uniformly dispersed CeO2 NPs between the rGO sheets, which enhanced the conductivity, as confirmed by SEM, EDS mapping, and XRD analysis. Cyclic voltammetry data demonstrated superior electrochemical activity of the CeO2/rGO composite electrodes, with the 2rGO/1CeO2 ratio showing the highest current response and sensitivity. The CV response to varying ammonia concentrations exhibited a linear relationship, indicating the electrode's capability for accurate quantification. These findings highlight the effectiveness of focused laser ablation in enhancing nanoparticle synthesis and the promising synergistic effects of CeO2 and rGO in developing high-performance electrochemical sensors.

A smartphone-based electrochemical sensing platform for the portable and simultaneous determination of flavonoids in Citri Reticulatae Pericarpium.

BACKGROUND: The efficient and timely determination of polymethoxylated flavones (PMFs, primarily nobiletin and tangeretin) and flavanone glycosides (primarily hesperidin) in Citri Reticulatae Pericarpium (CRP) is of paramount importance for the production of CRP and the evaluation of its efficacy. Conventional analytical methods including chromatography-based approaches commonly provide high sensitivity and selectivity, but require bulky equipment and complicated procedures performed by professional technicians and are thus inconvenient in practical applications. Therefore, there is a clear need for portable and miniaturized sensing platforms that can rapidly and simultaneously detect PMFs and hesperidin in CRP product. RESULTS: A state-of-the-art three-dimensional porous graphene electrode was first fabricated by direct laser scribing of a poly(ether-ether-ketone) (PEEK) film for electrocatalysis of nobiletin, tangeretin and hesperidin. Kinetic analysis was conducted to investigate the reaction mechanisms of these three flavonoids at such prepared PEEK-laser induced graphene (PEEK-LIG) electrodes. Since the as-prepared PEEK-LIG electrodes exhibited high electrocatalytic efficiency towards these three flavonoids, a portable electrochemical sensing platform assembled with a smartphone, a miniatured electrochemical workstation, and an integrated PEEK-LIG microchip was developed. Consequently, the developed portable electrochemical sensing platforms exhibited great sensitivity and low detection limits for both PMFs and hesperidin. More importantly, tests conducted on real CRP extract samples demonstrated that the developed portable electrochemical sensing platform exhibited high validity, high reliability, as well as excellent reproducibility. SIGNIFICANCE: This is the inaugural report on the portable and simultaneous determination of PMFs and hesperidin in the pericarp of Citrus Reticulata, which may be utilized for differentiating CRP products. Furthermore, the portable and powerful electrochemical sensing platforms developed could also potentially be applied for a wide range of analytes, thanks to their simple and rapid fabrication and determination processes.

CuO-ZIF-8 modified electrode surface as a new electrochemical sensing platform for detection of free chlorine in aqueous solution.

This work has applied metal-organic frameworks (MOFs) with high adsorbability and catalytic activity to develop electrochemical sensors to determine free chlorine (free-Cl) concentrations in aqueous media. A zeolitic imidazolate frameworks, Zn(Hmim)2 (ZIF-8) has been synthesized and incorporated with CuO nanosheets to decorate a glassy carbon electrode (GCE) and provide a new sensor for free-Cl determination. The as-prepared ZIF-8 and CuO-ZIF-8 composites have been characterized by FESEM, EDX, XRD, and FT-IR analyses. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) utilized to characterize the CuO-ZIF-8/GC modified electrode electrochemically, demonstrated the ability of the sensor to measure free-Cl concentration. Using differential pulse voltammetry (DPV) and under the optimal conditions, the prepared CuO-ZIF-8/GC modified electrode showed a linear response in the 0.25-60 ppm range with a 12 ppb detection limit (LOD) for free-Cl concentration. Finally, the fabricated sensor was applied to analyze free-Cl from actual swimming pool water samples with promising 97.5 to 103.0% recoveries.

Electrochemical Detection of Ascorbic Acid by Fe2O3 Nanoparticles Modified Glassy Carbon Electrode.

Background  The article delineates a strategy for detecting ascorbic acid (AA) through the use of iron oxide (Fe2O3) nanoparticles on an electrode. The Fe2O3 nanoparticles demonstrated effective electrocatalysis in the oxidation of AA, resulting in increased peak currents. The sensor showcased a wide linear detection range, a low detection limit, and high selectivity towards interferents, making it suitable for accurate AA measurement in food analysis and medical diagnostics applications. This emphasizes the potential of Fe2O3 nanoparticle-based sensors for precise AA detection. Aim The primary aim of this research is to develop an electrochemical sensing technique for the identification of ascorbic acid, with the use of Fe2O3 nanoparticles as the sensing matrix. Materials and methods The synthesis process involved the utilization of FeCl3.6H2O, ammonia solution, ethanol, and double-distilled water. FeCl3.6H2O was dissolved in ammonia water to produce a brown precipitate for the synthesis of Fe2O3 nanoparticles. Subsequently, the brown precipitate underwent hydrothermal treatment at 180 °C, resulting in the formation of a red product. Following centrifugation, washing, and drying steps, Fe2O3 nanoparticles were successfully synthesized. These nanoparticles were then utilized to modify the glassy carbon electrode (GCE). Prior to the modification, the GCE underwent polishing and cleaning procedures, after which it was coated with a suspension containing 5 mg of Fe2O3 nanoparticles in 10 mL of ethanol. The coated electrode was dried and deemed ready for application in electrochemical sensing. Results The hydrothermal method was employed in this research to synthesize Fe2O3 nanoparticles, which were subsequently subjected to a series of experiments to evaluate their electrochemical sensing capabilities. The resulting Fe2O3 nanoparticles were determined to possess a high level of purity and a crystalline structure through various analyses, including field emission-scanning electron microscopy (FE-SEM), cyclic voltammetric testing, X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy analysis, differential pulse voltammetry (DPV), and the current response of the Fe2O3-modified electrode towards ascorbic acid. The morphology of the Fe2O3 nanoparticles was observed to be uniform. The synthesized particles successfully fulfilled the study's objective by exhibiting remarkably sensitive and selective sensitivity towards ascorbic acid. Conclusion Our study underscores the potential of utilizing Fe2O3 nanoparticle-based electrochemical sensing to detect ascorbic acid, as evidenced by the notably high sensitivity of ascorbic acid towards Fe2O3 nanoparticles. The distinctive properties of Fe2O3 nanoparticles, which include their large surface area, efficient electron transport, and straightforward manufacturing process, significantly enhance the sensor's performance. Further research is crucial to exploring the wide-ranging applications of the sensor in fields such as food safety, environmental monitoring, and biological diagnostics and to overcome any existing limitations.

Highly Sensitive Biosensors Based on All-PEDOT:PSS Organic Electrochemical Transistors with Laser-Induced Micropatterning.

Recent advances in numerous biological applications have increased the accuracy of monitoring the level of biologically significant analytes in the human body to manage personal nutrition and physiological conditions. However, despite promising reports about costly wearable devices with high sensing performance, there has been a growing demand for inexpensive sensors that can quickly detect biological molecules. Herein, we present highly sensitive biosensors based on organic electrochemical transistors (OECTs), which are types of organic semiconductor-based sensors that operate consistently at low operating voltages in aqueous solutions. Instead of the gold or platinum electrode used in current electrochemical devices, poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) was used as both the channel and gate electrodes in the OECT. Additionally, to overcome the patterning resolution limitations of conventional solution processing, we confirmed that the irradiation of a high-power IR laser (λ = 1064 nm) onto the coated PEDOT:PSS film was able to produce spatially resolvable micropatterns in a digital-printing manner. The proposed patterning technique exhibits high suitability for the fabrication of all-PEDOT:PSS OECT devices. The device geometry was optimized by fine-tuning the gate area and the channel-to-gate distance. Consequently, the sensor for detecting ascorbic acid (vitamin C) concentrations in an electrolyte exhibited the best sensitivity of 125 µA dec-1 with a limit of detection of 1.3 µM, which is nearly 2 orders of magnitude higher than previous findings. Subsequently, an all-plastic flexible epidermal biosensor was established by transferring the patterned all-PEDOT:PSS OECT from a glass substrate to a PET substrate, taking full advantage of the flexibility of PEDOT:PSS. The prepared all-plastic sensor device is highly cost-effective and suitable for single-use applications because of its acceptable sensing performance and reliable signal for detecting vitamin C. Additionally, the epidermal sensor successfully obtained the temporal profile of vitamin C in the sweat of a human volunteer after the consumption of vitamin C drinks. We believe that the highly sensitive all-PEDOT:PSS OECT device fabricated using the accurate patterning process exhibits versatile potential as a low-cost and single-use biosensor for emerging bioelectronic applications.

Electrochemical identification of reductive enantiomers in wood channels: A low-cost and scalable platform for chiral sensing.

Chirality, an inherent characteristic of natural substances (such as sugars, peptides, proteins, and nucleic acid), plays a vital role in human metabolism and exerts substantial impacts. In general, chiral drugs can display diverse pharmacological and pharmacokinetic properties. One enantiomer may exhibit therapeutic effects, while the other could cause adverse reactions. Selective recognition of enantiomers is thus a significant task in the biomolecular and pharmaceutical fields. Despite the development of several chiral identification techniques, low-cost enantioselective sensing methods remain highly desirable. Here, we designed and developed an electrochemical sensing device for reductive enantiomer identification using natural wood channels as the substrate. The wood channels were endowed with oxidase-like activity through the in-situ growth of cerium oxide nanoparticles (CeO2). Chiral recognition capability was further introduced by incorporating a layer of chiral ZIF-8 (L-ZIF) as the chiral selector. To demonstrate the enantioselective sensing performance, 3,4-dihydroxyphenylalanine (DOPA) enantiomers were employed as model analytes. Due to the oxidase-like activity and the confinement effect of the proposed channels, the captured DOPA enantiomers were effectively oxidized to their quinone structure, and the Ce(IV) in CeO2 was reduced to Ce(III). These changes led to alterations in the surface charge of the channels, thereby modulating their ionic transport properties. This sensing mechanism also proved useful for the identification of other reductive enantiomers. The limits of detection for l-DOPA and d-DOPA were determined as 2.41 nM and 1.56 nM, respectively. The resulting wood channel-based sensing device not only can be used for the recognition and detection of reductive enantiomers, but also is expected to be applied to the non-electochemically active substances. Moreover, this study offers a novel type of solid-state channel material with low cost, reproducibility, and easy accessibility for electrochemical chiral sensing.

Alkaline metal tungstate anchored on functionalized-MWCNT: A co-active electrocatalyst for the detection of levofloxacin.

The widespread usage of levofloxacin (LVF) intake is executed for several urinary and respiratory systems infections in human. But, its over intake leads to severe damage to humans and the environment by its exposure. Hence the detection of LVF is concerned and we herein developed an electrocatalyst, strontium tungsten oxide nanospheres and later decorated onto the functionalized multiwall carbon nanotubes (SrWO4/f-MWCNT) to perform effective electrochemical recognition of LVF in aquatic and biological samples. Binary metal oxide with carbon composite SrWO4/f-MWCNT was developed due to its specific features as nanostructures. Various methods of investigation have been examined to identify the physiochemical characteristics like X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and morphological characteristics including field emission scanning electron microscopy, and transmission electron microscopy. The synthesized SrWO4/f-MWCNT sample crystalline size was around 32.9 nm. The SrWO4/f-MWCNT modified glassy carbon electrode (GCE) has been subjected to electrochemical investigation with a wide linear range of 0.049 µM-574.73 µM with good sensitivity 2.86 µA µM-1 cm2, the limit of detection at 14.9 nM for LVF sensing. Furthermore, the designed LVF detection exhibited excellent anti-interference, stability, reproducibility, and repeatability. The as-developed sensor's electrochemical outcomes indicate the superior performance inherent in the developed composite.

Co-crosslinking strategy for dual functionalization of small magnetic nanoparticles with redox probes and biological probes.

Surface functionalization strategy is becoming a crucial bridge from magnetic nanoparticles (MNPs) to their broad bio-application. To realize the multiple functions of MNPs such as magnetic manipulation, target capture, and signal amplification in their use of electrochemical biosensing, co-crosslinking strategy was proposed here to construct dual-functionalized MNPs by combining ultra-sensitive redox moieties and specific biological probes. In this work, MNPs with a TEM size of 10 nm were synthesized by co-precipitation for amination and PEGylation to maintain colloid stability once dispersed in high-ionic-strength buffer (such as phosphate-buffered saline). Then, MNPs@IgG were prepared via the bis(sulfosuccinimidyl) suberate (BS3) cross-linker to conjugate these IgG onto the MNP surface, with a binding efficiency of 73%. To construct dual-functionalized MNPs, these redox probes of ferrocene-NHS (Fc) were co-crosslinked onto the MNP surface, together with IgG, by using BS3. The developed MNPs@Redox@IgG were characterized by SDS‒PAGE to identify IgG binding and by square wave voltammetry (SWV) to validate the redox signal. Additionally, the anti-CD63 antibodies were selected for the development of MNPs@anti-CD63 for use in the bio-testing of exosome sample capture. Therefore, co-crosslinking strategy paved a way to develop dual-functionalized MNPs that can be an aid of their potential utilization in diagnostic assay or electrochemical methods.

Novel ZIFs nanostructures electro-engineered at carbon fiber for the highly sensitive and selective detection of isoeugenol.

Novel zeolitic imidazolate frameworks (ZIFs), classical subtypes of metal organic frameworks (MOFs), and nanostructures are electro-engineered onto carbon fiber (CF), leading to a unique freestanding electrochemical platform of budlike nano Zn-ZIFs decorated CF (BN-Zn-ZIFs/CF). The unique morphology, structure, and composition are characterized by electron microscopy and energy spectrum analysis. Notably, the BN-Zn-ZIFs/CF platform displays superb electrocatalysis towards the oxidation of isoeugenol with encouragingly low overpotential and high current response. The strong electrocatalytic oxidation capability of BN-Zn-ZIFs/CF makes it an excellent sensing platform for isoeugenol detection. BN-Zn-ZIFs/CF sensor exhibits high-performance isoeugenol sensing with an extremely low limit of detection (13 nM) and wide detection range (0.1-700 µM). Besides, the BN-Zn-ZIFs/CF sensor can greatly resist interference from common ions, major biomolecules, and some amino acids. Moreover, excellent reliability, stability, and practicality are obtained. Our work demonstrates that the as-prepared BN-Zn-ZIFs/CF can act as an high-performance electrochemical sensor for the isoeugenol detection, the well-developed ZIF nanocrystal-modified conductive substrates can be a unique platform for the efficient sensing of other molecules, and the electrochemical engineering strategy can be an effective method for the growing of fresh MOF nanocrystals at conductive substrates in various electrochemical applications.

Electrocatalysis Using Cobalt Porphyrin Covalently Linked with Multi-Walled Carbon Nanotubes: Hydrazine Sensing and Hydrazine-Assisted Green Hydrogen Synthesis.

Acid-treated multi-walled carbon nanotube (MWCNT) covalently functionalized with cobalt triphenothiazine porphyrin (CoTriPTZ-OH) A3B type porphyrin, containing three phenothiazine moieties (represented as MWCNT-CoTriPTZ) is synthesized and characterized by various spectroscopic and microscopic techniques. The nanoconjugate, MWCNT-CoTriPTZ, exhibits a pair of distinct redox peaks due to the Co2+/Co3+ redox process in 0.1 M pH 7.0 phosphate buffer. Further, it electrocatalytically oxidizes hydrazine at a low overpotential with a high current. This property is advantageously utilized for the sensitive determination of hydrazine. The developed electrochemical sensor exhibits high sensitivity (0.99 µAµM-1cm-2), a low limit of detection (4.5 ppb), and a broad linear calibration range (0.1 µM to 3.0 mM) for the determination of hydrazine. Further, MWCNT-CoTriPTZ is exploited for hydrazine-assisted green hydrogen synthesis. The high efficiency of hydrazine oxidation is confirmed by the low onset potential (0.45 V (vs RHE)) and 0.60 V (vs RHE) at the current density of 10 mA.cm-2. MWCNT-CoTriPTZ displays a high current density (77.29 mA.cm-2) at 1.45 V (vs RHE).

Capillary-driven microchip integrated with nickel phosphide hybrid-modified electrode for the electrochemical detection of glucose.

BACKGROUND: Transition metal phosphides with properties similar to platinum metal have received increasing attention for the non-enzymatic detection of glucose. However, the requirement of highly corrosive reagent during sample pretreatment would impose a potential risk to the human body, limiting their practical applications. RESULTS: In this study, we report a self-powered microfluidic device for the non-enzymatic detection of glucose using nickel phosphide (Ni2P) hybrid as the catalyst. The Ni2P hybrid is synthesized by pyrolysis of metal-organic framework (MOF)-based precursor and in-situ phosphating process, showing two linear detection ranges (1 µM-1 mM, 1 mM-6 mM) toward glucose with the detection limit of 0.32 µM. The good performance of Ni2P hybrid for glucose is attributed to the synergistic effect of Ni2P active sites and N-doped porous carbon matrix. The microchip is integrated with a NaOH-loaded paper pad and a capillary-based micropump, enabling the automatic NaOH redissolution and delivery of sample solution into the detection chamber. Under the optimized condition, the Ni2P hybrid-based microchip realized the detection of glucose in a user-friendly way. Besides, the feasibility of using this microchip for glucose detection in real serum samples has also been validated. SIGNIFICANCE: This article presents a facile fabrication method utilizing a MOF template to synthesize a Ni2P hybrid catalyst. By leveraging the synergy between the Ni2P active sites and the N-doped carbon matrix, an exceptional electrochemical detection performance for glucose has been achieved. Additionally, a self-powered chip device has been developed for convenient glucose detection based on the pre-established high pH environment on the chip.