Investigating the potential of monocyclic B9N9 and C18 rings for the electrochemical sensing, and adsorption of carbazole-based anti-cancer drug derivatives: DFT-based first-principle study.

CONTEXT: For the first time, the use of monocyclic rings C18 and B9N9 as sensors for the sensing of carbazole-based anti-cancer drugs, such as tetrahydrocarbazole (THC), mukonal (MKN), murrayanine (MRY), and ellipticine (EPT), is described using DFT simulations and computational characterization. The geometries, electronic properties, stability studies, sensitivity, and adsorption capabilities of C18 and B9N9 counterparts towards the selected compounds confirm that the analytes interact through active cavities of the C18 and B9N9 rings of the complexes. METHODS: Based on the interaction energies, the sensitivity of surfaces towards EPT, MKN, MRY, and THC analytes is observed. The interaction energy of EPT@B9N9, MKN@B9N9, MRY@B9N9, and THC@B9N9 complexes are observed - 20.40, - 19.49, - 20.07, and - 18.27 kcal/mol respectively which is more exothermic than EPT@C18, MKN@C18, MRY@C18, and THC@C18 complexes are - 16.37, - 13.97, - 13.96, and - 11.39 kcal/mol respectively. According to findings from the quantum theory of atoms in molecules (QTAIM) and the reduced density gradient (RDG), dispersion forces play a significant role in maintaining the stability of these complexes. The electronic properties including FMOs, density of states (DOS), natural bond orbitals (NBO), charge transfer, and absorption studies are carried out. In comparison of B9N9 and C18, the analyte recovery time for C18 is much shorter (9.91 × 10-11 for THC@C18) than that for B9N9 shorter recovery time value of 3.75 × 10-9 for EPT@B9N9. These results suggest that our reported sensors B9N9 and C18 make it faster to detect adsorbed molecules at room temperature. The sensor response is more prominent in B9N9 due to its fine energy gap and high adsorption energy. Consequently, it is possible to think of these monocyclic systems as a potential material for sensor applications.

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.

A comprehensive review of the application of Zr-based metal-organic frameworks for electrochemical sensors and biosensors.

A family of inorganic-organic hybrid crystalline materials made up of organic ligands and metal cations or clusters is known as metal-organic frameworks (MOFs). Because of their unique stability, intriguing characteristics, and structural diversity, zirconium-based MOFs (Zr-MOFs) are regarded as one of the most interesting families of MOF materials for real-world applications. Zr-MOFs that have the ligands, metal nodes, and guest molecules enclosed show distinct electrochemical reactions. They can successfully and sensitively identify a wide range of substances, which is important for both environmental preservation and human health. The rational design and synthesis of Zr-MOF electrochemical sensors and biosensors, as well as their applications in the detection of drugs, biomarkers, pesticides, food additives, hydrogen peroxide, and other materials, are the main topics of this comprehensive review. We also touch on the current issues and potential future paths for Zr-MOF electrochemical sensor research.

An ultrasensitive electrochemical/colorimetric dual-mode self-powered biosensing platform for lung cancer marker detection by multiple-signal amplification strategy.

BACKGROUND: In recent years, miRNAs have emerged as potentially valuable tumor markers, and their sensitive and accurate detection is crucial for early screening and diagnosis of tumors. However, the analysis of miRNAs faces significant challenges due to their short sequence, susceptibility to degradation, high similarity, low expression level in cells, and stringent requirements for in vitro research environments. Therefore, the development of sensitive and efficient new methods for the detection of tumor markers is crucial for the early intervention of related tumors. RESULTS: An ultrasensitive electrochemical/colorimetric dual-mode self-powered biosensor platform is established to detect microRNA-21 (miR-21) via a multi-signal amplification strategy. Gold nanoparticles (AuNPs) and VS4 nanosheets self-assembled 3D nanorods (VS4-Ns-Nrs) are prepared for constructing a superior performance enzyme biofuel cell (EBFC). The double-signal amplification strategy of Y-shaped DNA nanostructure and catalytic hairpin assembly (CHA) is adopted to further improve enhance the strength and specificity of the output signal. In addition, a capacitor is matched with EBFC to generate an instantaneous current that is amplified several times, and the output detection signal is improved once more. At the same time, electrochemical and colorimetric methods are used for dual-mode strategy to achieve the accuracy of detection. The linear range of detection is from 0.001 pg/mL to 1000 pg/mL, with a relatively low limit of detection (LOD) of 0.16 fg/mL (S/N = 3). SIGNIFICANCE: The established method enables accurate and sensitive detection of markers in patients with lung cancer, providing technical support and data reference for precise identification. It is anticipated to offer a sensitive and practical new technology and approach for early diagnosis, clinical treatment, and drug screening of cancer and other related major diseases.

Application of CRISPR/Cas12a in miRNA-155 detection: A novel homogeneous electrochemiluminescence biosensor.

BACKGROUND: MicroRNAs (miRNAs) are important non-coding RNA entities that affect gene expression and function by binding to target mRNAs, leading to degradation of the mRNAs or inhibiting their translation. MiRNAs are widely involved in a variety of biological processes, such as cell differentiation, development, metabolism, and apoptosis. In addition, miRNAs are associated with many diseases, including cancer. However, conventional detection techniques often suffer from shortcomings such as low sensitivity, so we need to develop a rapid and efficient detection strategy for accurate detection of miRNAs. RESULTS: We have developed an innovative homogeneous electrochemiluminescence (ECL) biosensor. This biosensor employs CRISPR/Cas12a gene editing technology for accurate and efficient detection of microRNA (miRNA). Compared to conventional technologies, this biosensor employs a unique homogeneous detection format that eliminates laborious probe fixation steps and greatly simplifies the detection process. By using two amplification techniques - isothermal amplification and T7 RNA polymerase amplification - the biosensor improves the sensitivity and specificity of the assay, providing excellent detection performance in the assay. This makes it possible to evaluate miRNA directly from a variety of biological samples such as cell lysates and diluted human serum. Experimental results convincingly demonstrate the extraordinary performance of this biosensor, including its extremely low detection limit of 1.27 aM, high sensitivity, reproducibility and stability. SIGNIFICANCE: The application of our constructed sensor in distinguishing between cancerous and non-cancerous cell lines highlights its potential for early cancer detection and monitoring. This innovative approach represents a major advancement in the field of miRNA detection, providing a user-friendly, cost-effective, and sensitive solution with broad implications for clinical diagnosis and patient care, especially in point-of-care settings.

Electrochemical chiral sensor for recognition of amino acid enantiomers with cyclodextrin-based microporous organic networks.

BACKGROUND: Chirality is a ubiquitous phenomenon in nature, but enantiomers exhibit different pharmacological activities and toxicological effects. Therefore, Chiral recognition plays a pivotal role in various fields such as life sciences, chemical synthesis, drug development, and materials science. The synthesis of novel chiral composites with well-defined loading capabilities and ordered structures holds significant potential for electrochemical chiral recognition applications. However, the design of selective and stable electrochemical chiral recognition materials remains a challenging task. RESULT: In this work, we construct a simple and rapid electrochemical sensing platform for tryptophan (Trp) enantiomer recognition using cyclodextrin-modified microporous organic network as chiral recognition agent. CD-MON with chiral microenvironment was prepared by Sonogashira-Hagihara coupling reaction of the chiral molecule heptyl-6-iodo-6-deoxyß-cyclodextrin and 1, 4-Diethynylbenzene. The adhesion of BSA makes CD-MON firmly fixed on the electrode surface, and as a chiral protein, it can improve the chiral recognition ability through synergistic effect. Chiral amino acids are in full contact with the chiral microenvironment during pore conduction of MON, and L-Trp is more stably bound to CD-MON/BSA due to steric hindrance, host-guest recognition and hydrogen bonding. Therefore, the electrochemical sensor can effectively identify tryptophan enantiomers (IL-Trp/ID-Trp = 2.02), and it exhibits a detection limit of 2.6 µM for L-Trp. UV-Vis spectroscopy confirmed the adsorption capacity of CD-MON towards tryptophan enantiomers in agreement with electrochemistry results. SIGNIFICANCE: The prepared chiral sensor has excellent stability, reproducibility (RSD = 3.7%) and selectivity, realizes the quantitative detection of single isomer in tryptophan racemic and quantitative analysis in real samples with 94.0%-101.0% recovery. This work represents the first application of MON in chiral electrochemistry which expands the application scope of chiral sensors and holds great significance in separation science and electrochemical sensing.

A novel ratiometric electrochemical sensing platform combined with molecularly imprinted polymer and Fe-MOF-NH2/CNTs-NH2/MXene composite for efficient detection of ofloxacin.

BACKGROUND: Ofloxacin (OFL) is often abused in medicine and animal husbandry, which poses a great threat to human health and ecological environment. Therefore, it is necessary to establish efficient method to detect OFL. Electrochemical sensor has attracted widespread attention due to the advantages of low cost and fast response. However, most electrochemical sensors usually use one response signal to detect the target, which makes it sensitive to the variable background noise in the complex environment, resulting in low robustness and selectivity. The ratio detection mode and employing molecularly imprinted polymer (MIP) are two strategies to solve these problems. RESULTS: A novel molecular imprinting polymer-ratiometric electrochemical sensor (MIP-RECS) based on Fe-MOF-NH2/CNTs-NH2/MXene composite was prepared for the rapid and sensitive detection of OFL. The positively charged Fe-MOF-NH2 and CNTs-NH2 as interlayer spacers were introduced into the negatively charged MXene through a simple electrostatic self-assembly technique, which effectively prevented the agglomeration of MXene and increased the electrocatalytic activity. A glass carbon electrode was modified by the composite and a MIP film was electropolymerized on it using o-phenylenediamine and ß-cyclodextrin as bifunctional monomers and OFL as template. Then a MIP-RECS was designed by adding dopamine (DA) into the electrolyte solution as internal reference, and OFL was quantified by the response current ratio of OFL to DA. The current ratio and the concentration of OFL displayed a satisfying linear relationship in the range of 0.1 µM-100 µM, with a limit of detection (LOD) of 13.2 nM. SIGNIFICANCE: Combining molecular imprinting strategy and ratio strategy, the MIP-RECS has impressive selectivity compared with the non-imprinted polymer-RECS, and has better repeatability and reproducibility than non-ratiometric sensor. The MIP-RECS has high sensitivity and accuracy, which was applied for the detection of OFL in four different brands of milk and was verified by HPLC method with satisfactory results.

A novel photoelectrochemical aptasensor based on 3D flower-like g-C3N4/BiOI p-n heterojunction for the sensitive detection of kanamycin.

BACKGROUND: Kanamycin (KAN) residues in animal-derived foods continuously enter the human body, which will pose serious threats to human health such as hearing loss, nephrotoxicity and other complications. Therefore, to sensitively detect KAN residues by a reliable technology is extremely urgent in food quality and safety. Compared with traditional methods being limited by cost and complexity, photoelectrochemical (PEC) biosensors benefit from some merits such as rapid response, excellent sensitivity and good stability. In this study, the construction of a highly efficient PEC platform to realize KAN residues detection is discussed. RESULTS: Herein, a novel p-n heterojunction consisting of flower-like BiOI microspheres and graphite carbon nitride (g-C3N4) nanoflakes was developed to establish a PEC aptasensor for KAN detection at 0 V. The prepared g-C3N4/BiOI heterostructure showed not only significantly enhanced PEC activity due to the larger specific surface area but also greatly increased charge separation efficiency owing to the strong internal electric field. Meanwhile, using g-C3N4/BiOI as a highly efficient photoactive material for binding amine-functionalized aptamers to capture KAN, the photocurrent signals showed a 'turn off' mode to achieve the sensitive detection of KAN. The proposed PEC aptasensor exhibited linear response for KAN from 5 × 10-9 to 3 × 10-7 mol L-1 with a low detection limit of 1.31 × 10-9 mol L-1, and satisfactory recoveries (97.44-107.38 %) were obtained in real food samples analysis. SIGNIFICANCE: This work presented a novel p-n heterojunction-based PEC aptasensor with strong selectivity and stability, rendering it allowed to detect KAN in animal-derived foods including milk, honey and pork. Additionally, the detection range satisfied the MRLs for KAN specified by the national standards, demonstrating the potential application for food analysis. The study provides a new insight into the development of efficient and practical biosensors for antibiotic residues detection.

Performance of a polymerization-based electrochemically assisted persulfate process on a real coking wastewater treatment.

Industrial wastewater should be treated with caution due to its potential environmental risks. In this study, a polymerization-based cathode/Fe3+/peroxydisulfate (PDS) process was employed for the first time to treat a raw coking wastewater, which can achieve simultaneous organics abatement and recovery by converting organic contaminants into separable solid organic-polymers. The results confirm that several dominant organic contaminants in coking wastewater such as phenol, cresols, quinoline and indole can be induced to polymerize by self-coupling or cross-coupling. The total chemical oxygen demand (COD) abatement from coking wastewater is 46.8% and the separable organic-polymer formed from organic contaminants accounts for 62.8% of the abated COD. Dissolved organic carbon (DOC) abatement of 41.9% is achieved with about 89% less PDS consumption than conventional degradation-based process. Operating conditions such as PDS concentration, Fe3+ concentration and current density can affect the COD/DOC abatement and organic-polymer yield by regulating the generation of reactive radicals. ESI-MS result shows that some organic-polymers are substituted by inorganic ions such as Cl-, Br-, I-, NH4+, SCN- and CN-, suggesting that these inorganic ions may be involved in the polymerization. The specific consumption of this coking wastewater treatment is 27 kWh/kg COD and 95 kWh/kg DOC. The values are much lower than those of the degradation-based processes in treating the same coking wastewater, and also are lower than those of most processes previously reported for coking wastewater treatment.

Demulsification with simultaneous water purification by coupling filtration and enhanced oil droplet coalescence at anode interface in an electrochemical reactor.

With the increasing demand of recycling disposal of industrial wastewater, oil-in-water (O/W) emulsion has been paid much attention in recent years owing to its high oil content. However, due to the presence of surfactant and salt, the emulsion was usually stable with complex physicochemical interfacial properties leading to increased processing difficulty. Herein, a novel flow-through electrode-based demulsification reactor (FEDR) was well designed for the treatment of saline O/W emulsion. In contrast to 53.7% for electrical demulsification only and 80.3% for filtration only, the COD removal efficiency increased to 92.8% under FEDR system. Moreover, the pore size of electrode and the applied voltage were two key factors that governed the FEDR demulsification performance. By observing the morphology of oil droplets deposited layer after different operation conditions and the behavior of oil droplets at the electrode surface under different voltage conditions, the mechanism was proposed that the oil droplets first accumulated on the surface of flow-through electrode by sieving effect, subsequently the gathered oil droplets could further coalesce with the promoting effect of the anode, leading to a high-performing demulsification. This study offers an attractive option of using flow-through electrode to accomplish the oil recovery with simultaneous water purification.

Electrospun fibrillary scaffold for electrochemical cell biomarkers detection.

A novel scaffold for in situ electrochemical detection of cell biomarkers was developed using electrospun nanofibers and commercial adhesive polymeric membranes. The electrochemical sensing of cell biomarkers requires the cultivation of the cells on/near the (bio)sensor surface in a manner to preserve an appropriate electroactive available surface and to avoid the surface passivation and sensor damage. This can be achieved by employing biocompatible nanofiber meshes that allow the cells to have a normal behavior and do not alter the electrochemical detection. For a better mechanical stability and ease of handling, nylon 6/6 nanofibers were collected on commercial polymeric membranes, at an optimal fiber density, obtaining a double-layered platform. To demonstrate the functionality of the fabricated scaffold, the screening of cellular stress has been achieved integrating melanoma B16-F10 cells and the (bio)sensor components on the transducer whereas the melanin exocytosis was successfully quantified using a commercial electrode. Either directly on the surface of the (bio)sensor or spatially detached from it, the integration of cell cultures in biosensing platforms based on electrospun nanofibers represents a powerful bioanalytical tool able to provide real-time information about the biomarker release, enzyme activity or inhibition, and monitoring of various cellular events.

One-pot electrochemical detection of foodborne pathogen based on in situ nucleic acid amplification and wash-free assay.

A signal amplification electrochemical biosensor chip was developed to integrate loop-mediated isothermal amplification (LAMP) based on in situ nucleic acid amplification and methyl blue (MB) serving as the hybridization redox indicator for sensitive and selective foodborne pathogen detection without a washing step. The electrochemical biosensor chip was designed by a screen-printed carbon electrode modified with gold nanoparticles (Au NPs) and covered with polydimethylsiloxane membrane to form a microcell. The primers of the target were immobilized on the Au NPs by covalent attachment for in situ amplification. The electroactive MB was used as the electrochemical signal reporter and embedded into the double-stranded DNA (dsDNA) amplicons generated by LAMP. Differential pulse voltammetry was introduced to survey the dsDNA hybridization with MB, which differentiates the specifically electrode-unbound and -bound labels without a washing step. Pyrene as the back-filling agent can further improve response signaling by reducing non-specific adsorption. This method is operationally simple, specific, and effective. The biosensor showed a detection linear range of 102-107 CFU mL-1 with the limit of detection of 17.7 CFU mL-1 within 40 min. This method showed promise for on-site testing of foodborne pathogens and could be integrated into an all-in-one device.

Preparation of CoFe@C composite modified electrode for neohesperidin dihydrochalcone sensing and its application in Chinese medicine.

CoFe@C was first prepared by calcining the precursor of CoFe-metal-organic framework-74 (CoFe-MOF-74), then an electrochemical sensor for the determination of neohesperidin dihydrochalcone (NHDC) was constructed, which was stemmed from the novel CoFe@C/Nafion composite film modified glassy carbon electrode (GCE). The CoFe@C/Nafion composite was verified by field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Electrochemical impedance spectroscopy (EIS) was used to evaluate its electrical properties as a modified material for an electrochemical sensor. Compared with CoFe-MOF-74 precursor modified electrode, CoFe@C/Nafion electrode exhibited a great synergic catalytic effect and extremely increased the oxidation peak signal of NHDC. The effects of various experimental conditions on the oxidation of NHDC were investigated and the calibration plot was tested. The results bespoken that CoFe@C/Nafion GCE has good reproducibility and anti-interference under the optimal experimental conditions. In addition, the differential pulse current response of NHDC was linear with its concentration within the range 0.08 ~ 20 µmol/L, and the linear regression coefficient was 0.9957. The detection limit was as low as 14.2 nmol/L (S/N = 3). In order to further verify the feasibility of the method, it was successfully used to determine the content of NHDC in Chinese medicine, with a satisfactory result, good in accordance with that of high performance liquid chromatography (HPLC).

Hybrid nanoflower-based electrochemical lateral flow immunoassay for Escherichia coli O157 detection.

An electrochemical biosensor has been developed for detection of Escherichia coli O157 by integrating lateral flow with screen-printed electrodes. The screen-printed electrodes were attached under the lateral flow detection line, and organic-inorganic nanoflowers prepared from E. coli O157-specific antibodies as an organic component were attached to the lateral flow detection line. In the presence of E. coli O157, an organic-inorganic nanoflower-E. coli O157-antimicrobial peptide-labelled ferrocene sandwich structure is formed on the lateral flow detection line. Differential pulse voltammetry is applied using a smartphone-based device to monitor ferrocene on the detection line. The resulting electrochemical biosensor could specifically detect E. coli O157 with a limit of detection of 25 colony-forming units mL-1. Through substitution of antibodies of organic components in organic-inorganic nanoflowers, biosensors have great potential for the detection of other pathogens in biomedical research and clinical diagnosis.

CuxO decorated Ti3C2Tx MXene composites for non-enzymatic glucose sensing with large linear ranges.

Ti3C2Tx MXene/CuxO composites were prepared by acid etching combined with electrochemical technique. The abundant active sites on the surface of MXene greatly increase the loading of CuxO nanoparticles, and the synergistic effect between the different components of the composite can accelerate the oxidation reaction of glucose. The results indicate that at the working potential of 0.55 V (vs. Ag/AgCl), the glucose sensor based on Ti3C2Tx MXene/CuxO composite presents large linear concentration ranges from 1 µM to 4.655 mM (sensitivity of 361 µA mM-1 cm-2) and from 5.155 mM to 16.155 mM (sensitivity of 133 µA mM-1 cm-2). The limit of detection is 0.065 µM. In addition, the sensor effectively avoids the oxidative interference of common interfering species such as ascorbic acid, dopamine and uric acid. The sensor has good reproducibility, stability and acceptable recoveries for the detection of glucose in human sweat sample (97.5-103.3%) with RSD values less than 4%. Based on these excellent properties it has great potential for the detection of glucose in real samples.

Controlled synthesized of ternary Cu-Co-Ni-S sulfides nanoporous network structure on carbon fiber paper: a superior catalytic electrode for highly-sensitive glucose sensing.

BACKGROUND: Efficient monitoring of glucose concentration in the human body necessitates the utilization of electrochemically active sensing materials in nonenzymatic glucose sensors. However, prevailing limitations such as intricate fabrication processes, lower sensitivity, and instability impede their practical application. Herein, ternary Cu-Co-Ni-S sulfides nanoporous network structure was synthesized on carbon fiber paper (CP) by an ultrafast, facile, and controllable technique through on-step cyclic voltammetry, serving as a superior self-supporting catalytic electrode for the high-performance glucose sensor. RESULTS: The direct growth of free-standing Cu-Co-Ni-S on the interconnected three-dimensional (3D) network of CP boosted the active site of the composites, improved ion diffusion kinetics, and significantly promoted the electron transfer rate. The multiple oxidation states and synergistic effects among Co, Ni, Cu, and S further promoted glucose electrooxidation. The well-architected Cu-Co-Ni-S/CP presented exceptional electrocatalytic properties for glucose with satisfied linearity of a broad range from 0.3 to 16,000 µM and high sensitivity of 6829 µA mM- 1 cm- 2. Furthermore, the novel sensor demonstrated excellent selectivity and storage stability, which could successfully evaluate the glucose levels in human serum. Notably, the novel Cu-Co-Ni-S/CP showed favorable biocompatibility, proving its potential for in vivo glucose monitoring. CONCLUSION: The proposed 3D hierarchical morphology self-supported electrode sensor, which demonstrates appealing analysis behavior for glucose electrooxidation, holds great promise for the next generation of high-performance glucose sensors.

Bismuthene - Tetrahedral DNA nanobioconjugate for virus detection.

In this work, we present an electrochemical sensor for fast, low-cost, and easy detection of the SARS-CoV-2 spike protein in infected patients. The sensor is based on a selected combination of nanomaterials with a specific purpose. A bioconjugate formed by Few-layer bismuthene nanosheets (FLB) and tetrahedral DNA nanostructures (TDNs) is immobilized on Carbon Screen-Printed Electrodes (CSPE). The TDNs contain on the top vertex an aptamer that specifically binds to the SARS-CoV-2 spike protein, and a thiol group at the three basal vertices to anchor to the FLB. The TDNs are also marked with a redox indicator, Azure A (AA), which allows the direct detection of SARS-CoV-2 spike protein through changes in the current intensity of its electrolysis before and after the biorecognition reaction. The developed sensor can detect SARS-CoV-2 spike protein with a detection limit of 1.74 fg mL-1 directly in nasopharyngeal swab human samples. Therefore, this study offers a new strategy for rapid virus detection since it is versatile enough for different viruses and pathogens.

Development of a microfluidic wearable electrochemical sensor for the non-invasive monitoring of oxidative stress biomarkers in human sweat.

Oxidative stress is widely recognized as a pivotal factor contributing to numerous Central Nervous System (CNS) ailments. The concentrations of hydrogen peroxide (H2O2) and phosphorylated proteins within the human body serve as crucial indicators of oxidative stress. As such, the real-time monitoring of H2O2 and phosphorylated proteins in sweat is vital for the early identification, diagnosis, and management of diseases linked to oxidative stress. In this context, we present a novel microfluidic wearable electrochemical sensor by modifying the electrode with Prussian blue (PB) and loading sulfur-rich vacancy-containing molybdenum disulfide (MoS2-X) onto Multi-walled carbon nanotube (CNTs) to form coaxially layered CNTs/MoS2-X, which was then synthesized with highly dispersed titanium dioxide nanoparticles (TiO2) to synthesize CNTs/MoS2-X/TiO2 composites for the detection of human sweat H2O2 and phosphorylated proteins, respectively. This structure, with its sulfur vacancies and coaxial layering, significantly improved sensitivity of electrochemical sensors, allowing it to detect H2O2 in a range of 0.01-1 mM with a detection limit of 4.80 µM, and phosphoproteins in a range of 0.01-1 mg/mL with a threshold of 0.917 µg/mL. Furthermore, the miniature sensor demonstrates outstanding performance in detecting analytes in both simulated and real sweat. Comprehensive biosafety assessments have validated the compatibility of the electrode material, underscoring the potential of sensor as a reliable and non-invasive method for tracking biomarkers linked to CNS disorders. This microfluidic wearable electrochemical biosensor with high performance and biosafety features shows great promise for the development of cutting-edge wearable technology devices for tracking CNS disease indicators.

Zr-based metalloporphyrin MOF probe for electrochemical detection of parathion-methyl.

An electrochemical (EC) sensor based on metalloporphyrin metal-organic framework (MOF) for the detection of parathion-methyl (PM) has been developed. The prepared MOF-525(Fe) exhibits great signal enhancement toward the electrochemical detection of PM owing to its unique structural properties and electrochemical activities. Under optimal experimental conditions, the as-prepared MOF-525(Fe) based EC sensor exhibited excellent PM sensing performance with a wide linear detection range (0.1 µM-100 µM) and low limit of detection (LOD, 1.4 nM). Compared to its corresponding Fe metalloporphyrin (linker), MOF-525(Fe) exhibited a superior sensitivity (28.31 µA cm-2·µM-1), which is 3.7 times higher than the sensitivity of FeTCPP linker (7.56 µA cm-2·µM-1) towards PM. The improved performance is associated with the high specific surface area and the large pore channels of MOF-525(Fe) facilitating a better interaction between PM and the Fe metalloporphyrin active sites, especially in the lower concentration range. Moreover, a possible affinity of the PM molecules toward Zr6 clusters may also contribute to the selective enrichment of PM on MOF-525(Fe). This EC sensor further demonstrated high selectivity in the presence of interfering molecules. The recovery results further confirm accurate PM sensing in actual samples, which suggests promising applications for the rapid detection of environmental organophosphates by metalloporphyrin MOFs.

Transient paper-based electrochemical biosensor Fabricated by superadditive Cu-TCPP(Fe)/Mxene for Multipathway non-invasive, highly sensitive detection of Bodily metabolites.

Current advances in non-invasive fluid diagnostics highlight unique benefits for monitoring metabolic diseases. However, the low concentrations and complex compositions of biomarkers in fluids such as sweat, urine, and saliva impose stringent demands on the sensitivity and stability of detection technologies. Here, we developed a high-sensitivity, low-cost instantaneous electrochemical sensor based on the superadditive effect mechanism of Cu-TCPP(Fe)/Mxene (MMs Paper-ECL Sensor), which has been successfully applied for the simultaneous real-time detection of glucose and uric acid. Strong interfacial interactions between Mxene and Cu-TCPP(Fe) were revealed through precise simulation calculations and multi-dimensional characterization analysis, significantly enhancing the sensor's electrocatalytic performance and reaction kinetics. Experimentally, this exceptional electrocatalytic activity was demonstrated in its unprecedented high sensitivity and wide linear detection range for glucose and uric acid, with a non-invasive linear range from 0.001 nM to 5 mM, 0.025 nM-5 mM, detection limits as low as 1.88 aM and 5.80 pM, and stability extending up to 100 days. This represents not only a breakthrough in sensitivity and stability but also provides an effective, low-cost solution that overcomes the limitations of existing electronic devices, enabling multi-channel simultaneous detection. The universality of this sensor holds vast potential for application in the field of non-invasive fluid diagnostics.