A novel electrochemical sensor with NiSx@MoS2 composite for efficient NO2- sensing.

Excess nitrites are potentially threatening to human health, so it is urgent to develop accurate and sensitive methods. The development of sensors can provide early warning of possible hazards and alert people to protect public health. This work presents an NiSx@MoS2-composite with excellent electrochemical activity, representing a key finding for highly sensitive NO2- detection and sensor development. With the assistance of NiSx@MoS2, this electrochemical sensor has excellent quantitative detection performance. It has a wide detection range (0.0001-0.0020 mg/mL) and a low detection limit (1.863*10-5 mg/mL) for NO2-. This electrochemical sensor maintains excellent specificity among numerous interferences, and it completes the accurate detection of different real food samples. Pleasingly, the electrochemical sensor has satisfactory repeatability stability, and potential for practical applications. It would demonstrate tremendous potential in scientific dietary guidance, food safety detection and other fields.

Ti3C2 MXene/MoS2@AuNPs ternary nanocomposite for highly sensitive electrochemical detection of phoxim residues in fruits.

Phoxim, extensively utilized in agriculture as an organothiophosphate insecticide, has the potential to cause neurotoxicity and pose human health hazards. In this study, an electrochemical enzyme biosensor based on Ti3C2 MXene/MoS2@AuNPs/AChE was constructed for the sensitive detection of phoxim. The two-dimensional multilayer structure of Ti3C2 MXene provides a robust framework for MoS2, leading to an expansion of the specific surface area and effectively preventing re-stacking of Ti3C2 MXene. Additionally, the synergistic effect of self-reduced grown AuNPs with MoS2 further improves the electrical conductivity of the composites, while the robust framework provides a favorable microenvironment for immobilization of enzyme molecules. Ti3C2 MXene/MoS2@AuNPs electrochemical enzyme sensor showed a significant response to phoxim in the range of 1 × 10-13 M to 1 × 10-7 M with a detection limit of 5.29 × 10-15 M. Moreover, the sensor demonstrated excellent repeatability, reproducibility, and stability, thereby showing its promising potential for real sample detection.

A novel electrochemical sensor for rapid detection of sulfathiazole by integrating [(4,4'-bipy/P2Mo17Co)n] modified electrode.

In this study, we focused on the successful construction of [(4,4'-bipy/P2Mo17Co)6] modified electrodes using the layer-by-layer assembly method for the sensitive detection of sulfathiazole (ST). The redox reaction between ST and the metal ions in the modified layer leads to the transfer of electrons, resulting in the generation of the electrical signal. The introduction of 4,4'-bipyridine (4,4'-bipy) enhanced the molecular recognition of ST by the modified electrode. Under the combined effect of P2Mo17Co and 4,4'-bipy, the sensor exhibited good performance for ST detection (LOD: 0.5616 µM, linear ST concentration range: 0-50 µM). The spiked recoveries of the two groups were 84.4%-103.2% and 90.9%-109.4% for the determination of ST residues in large yellow croaker and South American white shrimp, respectively. In addition, the electrode showed excellent performance in terms of stability, reproducibility, and anti-interference ability.

An electrochemical sensor based on 2D Zn-MOFs and 2D C-Ti3C2Tx composite materials for rapid and direct detection of various foodborne pathogens.

Rapid screening for foodborne pathogens is crucial for food safety. A rapid and one-step electrochemical sensor has been developed for the detection of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Salmonella typhimurium (S. typhimurium). Through the construction of aptamer/two-dimensional carboxylated Ti3C2Tx (2D C-Ti3C2Tx)/two-dimensional Zn-MOF (2D Zn-MOF) composites, the recognition elements, signal tags, and signal amplifiers are integrated on the electrode surface. Pathogens are selectively captured using the aptamer, which increases the impedance of the electrode surface，leads to a decrease in the 2D Zn-MOF current. Bacteria can be rapidly quantified using a one-step detection method and the replacement of aptamers. The detection limits for E. coli, S. aureus, and S. typhimurium are 6, 5, and 5 CFU·mL-1, respectively. The sensor demonstrated reliable detection capabilities in real-sample testing. Therefore, the one-step sensor based on the 2D Zn-MOF and 2D C-Ti3C2Tx has significant application value in the detection of foodborne pathogens.

Post-modification of covalent organic framework functionalized aminated carbon nanotubes with active site (Fe) for the sensitive detection of luteolin.

In this research, the TT-COF(Fe)@NH2-CNTs was innovatively prepared through a post-modification synthetic process functionalized TT-COF@NH2-CNTs with active site (Fe), where TT-COF@NH2-CNTs was prepared via a one-pot strategy using 5,10,15,20-tetrakis (para-aminophenyl) porphyrin (TTAP), 2,3,6,7-tetra (4-formylphenyl) tetrathiafulvalene (TTF) and aminated carbon nanotubes (NH2-CNTs) as raw materials. The complex TT-COF(Fe)@NH2-CNTs material possessed porous structures, outstanding conductivity and rich catalytic sites. Thus, it can be adopted to construct electrochemical sensor with glassy carbon electrode (GCE). The TT-COF(Fe)@NH2-CNTs/GCE can selectively detect luteolin (Lu) with a wide linear plot ranging from 0.005 to 3 µM and a low limit of detection (LOD) of 1.45 nM (S/N = 3). The Lu residues in carrot samples were determined using TT-COF(Fe)@NH2-CNTs sensor and UV-visible (UV-Vis) approach. This TT-COF(Fe)@NH2-CNTs/GCE sensor paves the way for the quantification of Lu through a cost-efficient and sensitive electrochemical approach, which can make a significant step in the sensing field based on crystalline COFs.

Combination of electrochemical advanced oxidation and biotreatment for wastewater treatment and soil remediation.

The global concern surrounding the advancement of methods for treating wastewater and polluted soil has markedly increased over time. While electrochemical advanced oxidation processes (EAOPs) and biotreatments are commonly employed technologies for remediating wastewater and polluted soil, their widespread adoption is hindered by their limitations, which include high costs associated with EAOPs and prolonged remediation time of biotreatments. In the review, we provided an overview of EAOP technology and biotreatment, emphasizing the critical aspects involved in building a combined system. This review systematically evaluates recent research that combines EAOPs with bioremediation for treating wastewater or contaminated soil as pretreatment or post-treatment process. Research findings suggest that the combined treatment method represents a promising and competitive technology that can overcome some of the limitations of individual treatments. Additionally, we discussed the potential applications of this technology in varying levels of wastewater and soil pollution, as well as the underlying combination mechanisms.

Advancing antibiotic detection and degradation: recent innovations in graphitic carbon nitride (g-C3N4) applications.

The uncontrolled release of antibiotics into the environment would be extremely harmful to human health and ecosystems. Therefore, it is in urgent need to monitor the environment and promote the detection and degradation of antibiotics to the relatively harmless by-products to a feasible extent. Graphitic carbon nitride (g-C3N4) is a non-metallic n-type semiconductor that can be used for the antibiotic detection and degradation due to its easy synthesis process, excellent chemical stability and unique optical properties. Unfortunately, the utilization of visible light, electron-hole recombination and electron conductivity have hindered its potential applications in the fields of photocatalytic degradation and electrochemical detection. Although previous publications have highlighted the diverse modification methods for the g-C3N4-based materials, the underlying structure-performance relationships of g-C3N4, especially for the detection and degradation of antibiotics, remains to be further explored. In view of this, the current review centered on the recent progress in the modification techniques of g-C3N4, the detection and degradation of antibiotics using the g-C3N4-based materials, as well as the potential antibiotic degradation mechanisms of the g-C3N4-based materials. Additionally, the underlying applications of the g-C3N4-based materials for antibiotic detection and degradation were also prospected. This review would provide a valuable research foundation and the up-to-date information for the g-C3N4-based materials to combat antibiotic pollution in the environment.

A highly sensitive electrochemical sensor based on poly(3-aminobenzoic acid)/graphene oxide-gold nanoparticles modified screen printed carbon electrode for paraquat detection.

Herein, a modified screen printed carbon electrode (SPCE) based on a composite material, graphene oxide-gold nanoparticles (GO-AuNPs), and poly(3-aminobenzoic acid)(P3ABA) for the detection of paraquat (PQ) is introduced. The modified electrode was fabricated by drop casting of the GO-AuNPs, followed by electropolymerization of 3-aminobenzoic acid to achieve SPCE/GO-AuNPs/P3ABA. The morphology and microstructural characteristics of the modified electrodes were revealed by scanning electron microscopy (SEM) for each step of modification. The composite GO-AuNPs can provide high surface area and enhance electroconductivity of the electrode. In addition, the presence of negatively charged P3ABA notably improved PQ adsorption and electron transfer rate, which stimulate redox reaction on the modified electrode, thus improving the sensitivity of PQ analysis. The SPCE/GO-AuNPs/P3ABA offered a wide linear range of PQ determination (10-9-10-4 mol/L) and low limit of detection (LOD) of 0.45 × 10-9 mol/L or 0.116 µg/L, which is far below international safety regulations. The modified electrode showed minimum interference effect with percent recovery ranging from 96.5% to 116.1% after addition of other herbicides, pesticides, metal ions, and additives. The stability of the SPCE/GO-AuNPs/P3ABA was evaluated, and the results indicated negligible changes in the detection signal over 9 weeks. Moreover, this modified electrode was successfully implemented for PQ analysis in both natural and tapped water with high accuracy.

2D copper-iron bimetallic metal-organic frameworks for reduction of nitrate with boosted efficiency and ammonia selectivity.

Electrocatalytic reduction of nitrate to ammonia has been considered a promising and sustainable pathway for pollutant treatment and ammonia has significant potential as a clean energy. Therefore, the method has received much attention. In this work, Cu/Fe 2D bimetallic metal-organic frameworks were synthesized by a facile method applied as cathode materials without high-temperature carbonization. Bimetallic centers (Cu, Fe) with enhanced intrinsic activity demonstrated higher removal efficiency. Meanwhile, the 2D nanosheet reduced the mass transfer barrier between the catalyst and nitrate and increased the reaction kinetics. Therefore, the catalysts with a 2D structure showed much better removal efficiency than other structures (3D MOFs and Bulk MOFs). Under optimal conditions, Cu/Fe-2D MOF exhibited high nitrate removal efficiency (87.8%) and ammonium selectivity (89.3%) simultaneously. The ammonium yielded up to significantly 907.2 µg/(hr·mgcat) (7793.8 µg/(hr·mgmetal)) with Faradaic efficiency of 62.8% at an initial 100 mg N/L. The catalyst was proved to have good stability and was recycled 15 times with excellent effect. DFT simulations confirm the reduced Gibbs free energy of Cu/Fe-2D MOF. This study demonstrates the promising application of Cu/Fe-2D MOF in nitrate reduction to ammonia and provides new insights for the design of efficient electrode materials.

Recent advances in electrochemical approaches for detection of nitrite in food samples.

Nitrite is a common ingredient in the industry and agriculture; it is everywhere, like water, food, and surroundings. Recently, several approaches have been developed to measure the nitrite levels. So, this review was presented as a summary of many approaches utilized to detect the nitrite. Furthermore, the types of information that may be acquired using these methodologies, including optic and electrical signals, were discussed. In electrical signal methods, electrochemical sensors are usually developed using different materials, including carbon, polymers, oxides, and hydroxides. At the same time, optic signals receiving techniques involve utilizing fluorescence chromatography, absorption, and spectrometry instruments. Furthermore, these methodologies' benefits, drawbacks, and restrictions are examined. Lastly, due to the efficiency and fast means of electrochemical detectors, it was suggested that they can be used for detecting nitrite in food safety. Futuristic advancements in the techniques used for nitrite determination are subsequently outlined.

Electrochemical biosensors for early detection of breast cancer.

Breast cancer continues to be a significant contributor to global cancer deaths, particularly among women. This highlights the critical role of early detection and treatment in boosting survival rates. While conventional diagnostic methods like mammograms, biopsies, ultrasounds, and MRIs are valuable tools, limitations exist in terms of cost, invasiveness, and the requirement for specialized equipment and trained personnel. Recent shifts towards biosensor technologies offer a promising alternative for monitoring biological processes and providing accurate health diagnostics in a cost-effective, non-invasive manner. These biosensors are particularly advantageous for early detection of primary tumors, metastases, and recurrent diseases, contributing to more effective breast cancer management. The integration of biosensor technology into medical devices has led to the development of low-cost, adaptable, and efficient diagnostic tools. In this framework, electrochemical screening platforms have garnered significant attention due to their selectivity, affordability, and ease of result interpretation. The current review discusses various breast cancer biomarkers and the potential of electrochemical biosensors to revolutionize early cancer detection, making provision for new diagnostic platforms and personalized healthcare solutions.

miRNA-based electrochemical biosensors for ovarian cancer.

Ovarian cancer, a prevalent and deadly cancer among women, presents a significant challenge for early detection due to its heterogeneous nature. MicroRNAs, short non-coding regulatory RNA fragments, play a role in various cellular processes. Aberrant expression of these microRNAs has been observed in the carcinogenesis-related processes of many cancer types. Numerous studies highlight the critical role of microRNAs in the initiation and progression of ovarian cancer. Given their clinical importance and predictive value, there has been considerable interest in developing simple, prompt, and sensitive miRNA biosensor strategies. Among these, electrochemical sensors have demonstrated advantageous characteristics such as simplicity, sensitivity, low cost, and scalability. These microRNA-based electrochemical biosensors are valuable tools for early detection and point-of-care applications. This article discusses the potential role of microRNAs in ovarian cancer and recent advances in the development of electrochemical biosensors for miRNA detection in ovarian cancer samples.

Ultrasonically assisted fabrication of electrochemical platform for tinidazole detection.

Based on sonochemistry, green synthesis methods play an important role in the development of nanomaterials. In this work, a novel chitosan modified MnMoO4/g-C3N4 (MnMoO4/g-C3N4/CHIT) was developed using ultrasonic cell disruptor (500 W, 30 kHz) for ultra-sensitive electrochemical detection of tinidazole (TNZ) in the environment. The morphology and surface properties of the synthesized MnMoO4/g-C3N4/CHIT electrode were characterized using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and transmission electron microscope (TEM). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were utilized to assess the electrochemical performance of TNZ. The results indicate that the electrochemical detection performance of TNZ is highly efficient, with a detection limit (LOD) of 3.78 nM, sensitivity of 1.320 µA·µM-1·cm-2, and a detection range of 0.1-200 µM. Additionally, the prepared electrode exhibits excellent selectivity, desirable anti-interference capability, and decent stability. MnMoO4/g-C3N4/CHIT can be successfully employed to detect TNZ in both the Songhua River and tap water, achieving good recovery rates within the range of 93.0 % to 106.6 %. Consequently, MnMoO4/g-C3N4/CHIT's simple synthesis might provide a new electrode for the sensitive, repeatable, and selective measurement of TNZ in real-time applications. Using the MnMoO4/g-C3N4/CHIT electrode can effectively monitor and detect the concentration of TNZ in environmental water, guiding the sewage treatment process and reducing the pollution level of antibiotics in the water environment.

A critical review of ozone-based electrochemical advanced oxidation processes for water treatment: Fundamentals, stability evaluation, and application.

In recent years, electrochemical advanced oxidation processes (EAOPs) combined with ozonation have been widely utilized in water/wastewater treatment due to their excellent synergistic effect, high treatment efficiency, and low energy consumption. A comprehensive summary of these ozone-based EAOPs is still insufficient, though some reviews have covered these topics but either focused on a specific integrated process or provided synopses of EAOPs or ozone-based AOPs. This review presents an overview of the fundamentals of several ozone-based EAOPs, focusing on process optimization, electrode selection, and typical reactor designs. Additionally, the service life of electrodes and improvement strategies for the stability of ozone-based EAOPs that are ignored by previous reviews are discussed. Furthermore, four main application fields are summarized, including disinfection, emerging contaminants treatment, industrial wastewater treatment, and resource recovery. Finally, the summary and perspective on ozone-based EAOPs are proposed. This review provides an overall summary that would help to gain insight into the ozone-based EAOPs to improve their environmental applications.

Systematic Study of Various Functionalization Steps for Ultrasensitive Detection of SARS-CoV-2 with Direct Laser-Functionalized Au-LIG Electrochemical Sensors.

The 2019 coronavirus (COVID-19) pandemic impaired global health, disrupted society, and slowed the economy. Early detection of the infection using highly sensitive diagnostics is crucial in preventing the disease's spread. In this paper, we demonstrate electrochemical sensors based on laser induced graphene (LIG) functionalized directly with gold (Au) nanostructures for the detection of SARS-CoV-2 with an outstanding limit of detection (LOD) of ∼1.2 ag·mL-1. To achieve the optimum performance, we explored various functionalization parameters to elucidate their impact on the LOD, sensitivity, and linearity. Specifically, we investigated the effect of (i) gold precursor concentration, (ii) cross-linker chemistry, (iii) cross-linker and antibody incubation conditions, and (iv) antigen-sensor interaction (diffusion-dominated incubation vs pipette-mixing), as there is a lack of a systematic study of these parameters. Our benchmarking analysis highlights the critical role of the antigen-sensor interaction and cross-linker chemistry. We showed that pipette-mixing enhances sensitivity and LOD by more than 1.6- and 5.5-fold, respectively, and also enables multimodal readout compared to diffusion-dominated incubation. Moreover, the PBA/Sulfo-NHS: EDC cross-linker improves the sensitivity and LOD compared to PBASE. The sensors demonstrate excellent selectivity against other viruses, including HCoV-229E, HCoV-OC43, HCoV-NL63, and influenza H5N1. Beyond the ability to detect antigen fragments, our sensors enable the detection of antigen-coated virion mimics (which are a better representative of the real infection) down to an ultralow concentration of ∼5 particles·mL-1.

Fully integrated sensor array for additives, permittivity, and pH monitoring for fishery.

Additive abuse in fishery, such as tricaine methanesulfonate (MS222), ciprofloxacin (CPFX), and malachite green (MG), threatens public human health and interferes with the ecological equilibrium of water resources. However, the majority of the present detection methods suffer from high costs, complex operations, and poor portability. Therefore, real-time and rapid detection of the above additive by mobile devices is becoming increasingly important. Here we report the fabrication and performance of an entirely electrochemical system with USB-stick size for simultaneous detection of MS222, CPFX, and MG, as well as pH and permittivity. The limits of detections are 0.17, 0.67, and 0.28 µg/mL, while the resolution ratios are 10 %, 10 %, and 5 % for MS222, MG, and CPFX, respectively. For both pH and permittivity, they have linear regressions measured by brightness and capacitance of the sample respectively, at the range of 1.5-9 (pH) and 10-20 (permittivity). The interference experiments, using target analytes (40 µg/mL) and 15 interfering analytes (80 µg/mL), demonstrated the anti-interference performance of the sensor patches. The field studies on carps, catfishes, and chubs indicated that the developed integrated portable system could be used for real sample analysis with high performance.

In-situ nanozyme catalytic amplification coupled with a universal antibody orientation strategy based electrochemical immunosensor for AD-related biomarker.

An in-situ nanozyme signal tag combined with a DNA-mediated universal antibody-oriented strategy was proposed to establish a high-performance immunosensing platform for Alzheimer's disease (AD)-related biomarker detection. Briefly, a Zr-based metal-organic framework (MOF) with peroxidase (POD)-like activity was synthesized to encapsulating the electroactive molecule methylene blue (MB), and subsequently modified with a layer of gold nanoparticles on its surface. This led to the creation of double POD-like activity nanozymes surrounding the MB molecule to form a nanozyme signal tag. A large number of hydroxyl radicals were generated by the nanozyme signal tag with the help of H2O2, which catalyzed MB molecules in situ to achieve efficient signal amplification. Subsequently, a DNA-aptamer-mediated universal antibody-oriented strategy was proposed to enhance the binding efficiency for the antigen (target). Meanwhile, a poly adenine was incorporated at the end of the aptamer, facilitating binding to the gold electrode and providing anti-fouling properties due to the hydrophilicity of the phosphate group. Under optimal conditions, this platform was successfully employed for highly sensitive detection of AD-associated tau protein and BACE1, achieving limits of detection with concentrations of 3.34 fg/mL and 1.67 fg/mL, respectively. It is worth mentioning that in the tau immunosensing mode, 20 clinical samples from volunteers of varying ages were analyzed, revealing significantly higher tau expression levels in the blood samples of elderly volunteers compared to young volunteers. This suggests that the developed strategy holds great promise for early AD diagnosis.

Sensitive and reliable lab-on-paper biosensor for label-free detection of exosomes by electrochemical impedance spectroscopy.

A new, sensitive, and cost-effective lab-on-paper-based immunosensor was designed based on electrochemical impedance spectroscopy (EIS) for the detection of exosomes. EIS was selected as the determination method since there was a surface blockage in electron transfer by binding the exosomes to the transducer. Briefly, the carbon working electrode (WE) on the paper electrode (PE) was modified with gold particles (AuPs@PE) and then conjugated with anti-CD9 (Anti-CD9/AuPs@PE) for the detection of exosomes. Variables involved in the biosensor design were optimized with the univariate mode. The developed method presents the limit of detection of  8.7 × 102 exosomes mL-1, which is lower than that of many other available methods under the best conditions. The biosensor was also tested with urine samples from cancer patients with high recoveries. Due to this  a unique, low-cost, biodegradable technology is presented that can directly measure exosomes without labeling them for early cancer or metastasis detection.

Efficient one-step synthesis of diarylacetic acids by electrochemical direct carboxylation of diarylmethanol compounds in DMSO.

An efficient one-step synthesis of diarylacetic acids was successfully performed by electrochemical direct carboxylation of diarylmethanol compounds in DMSO. Constant-current electrolysis of diarylmethanol species in DMSO using a one-compartment cell equipped with a Pt cathode and a Mg anode in the presence of carbon dioxide induced reductive C(sp3)-O bond cleavage at the benzylic position in diarylmethanol compounds and subsequent fixation of carbon dioxide to produce diarylacetic acids in good yield. This protocol provides a novel and simple approach to diarylacetic acids from diarylmethanol species and carbon dioxide without transformation of the hydroxy group into appropriate leaving groups, such as halides and esters including carbonates.

Mono-/Bimetallic Doped and Heterostructure Engineering for Electrochemical Energy Applications.

Designing efficient materials is crucial to meeting specific requirements in various electrochemical energy applications. Mono-/bimetallic doped and heterostructure engineering have attracted considerable research interest due to their unique functionalities and potential for electrochemical energy conversion and storage. However, addressing material imperfections such as low conductivity and poor active sites requires a strategic approach to design. This review explores the latest advancements in materials modified by mono-/bimetallic doped and heterojunction strategies for electrochemical energy applications. It can be subdivided into three key points: (i) the regulatory mechanisms of metal doping and heterostructure engineering for materials; (ii) the preparation methods of materials with various engineering strategies; and (iii) the synergistic effects of two engineering approaches, further highlighting their applications in supercapacitors, alkaline ion batteries, and electrocatalysis. Finally, the review concludes with perspectives and recommendations for further research to advance these technologies.