Analysis & sensing最新文献

Electrochemical sensors for hydrogen can be useful for development and optimization of water electrolyzers and fuel cells based on hydrogen evolution and oxidation reactions (HER and HOR). A nanometer-sized hydrogen sensor used as a tip in the scanning electrochemical microscope (SECM) can probe HER and HOR electrocatalysts and photocatalysts at the nanoscale. However, Pt tips and chemically modified nanoelectrodes previously employed for hydrogen sensing suffer from surface passivation, low amperometric signal, and stability issues. Here, the preparation of hydrogen sensors by covalently attaching ferrocene groups to the surface of Pt or carbon nanoelectrodes through oxidation of ferroceneacetate ions is reported. Mediated oxidation of hydrogen at surface-modified nanoelectrodes produces measurable and stable current suitable for amperometric measurements and SECM imaging.

A diaper-based, flexible, and miniature enzymatic biofuel cell (EBFC) is fabricated on carbon-coated conductive threads to detect glucose in the absence of a potentiostat. To construct the EBFC anode, 1,4-Naphthoquinone redox mediator is immobilized with glucose oxidase (GOx) on multi-walled carbon nanotubes. Ag/Ag₂O redox couple-based cathode is developed and integrated into BFC cathode due to its ability to perform even in a limited oxygen environment. Gold nanowires (AuNWs) are prepared and utilized for electrical wiring of GOx to the electrode surface. The EBFCs performance are found to be greatly enhanced (eight fold) in the presence of AuNWs with a maximum power density of 117 μW cm⁻² at an open circuit potential of 0.43 V. The EBFC shows linear increase in short-circuit currents when exposed to different glucose concentrations. This configuration enables precise glucose detection in the absence of a potentiostat. The results indicate that the sensor could detect a wide range of glucose (0.25–10 mM) in artificial urine and real human samples. The sensor exhibits remarkable selectivity toward glucose in the presence of common interferences. To validate the sensor's performance, urine and blood samples are collected from three diabetic and three healthy volunteers. The results show a good correlation between both measurements, with a Pearson correlation coefficient of 0.89, suggesting the efficiency of the smart diaper sensor for real-time urine analysis.

Electrochemical DNA-based biosensors have shown great potential in the rapid and highly accurate detection of Escherichia coli (E. coli), offering advantages over conventional microbial detection techniques. By leveraging hybrid nanointerfaces, these biosensors are emerging as a promising alternative for the rapid, accurate, and affordable detection of E. coli. These biosensors offer real-time pathogen monitoring with minimal sample preparation by utilizing the high sensitivity of electrochemical transduction and the specificity of DNA hybridization. This comprehensive review covers the basic principles of electrochemical DNA biosensor functioning, transduction mechanism-based classification, and different immobilization techniques to improve biosensing performance. Significant developments in signal amplification, nanomaterial integration, and electrode surface modifications-particularly through the design of hybrid nanointerfaces, are reviewed, showing enhancements in detection stability, sensitivity, and selectivity. Additionally, the integration of nanomaterials has greatly enhanced sensor performance by improving signal stability and reducing the detection time. Despite these developments, problems with sample complexity, sensor downsizing, and practical implementation still exist. This review aims to highlight the most recent advancements, potential commercialization applications, and future directions in the field to facilitate the development of next-generation biosensors for the detection of pathogens.

The clustered regularly interspaced short palindromic repeat (CRISPR)/Cas system, initially identified as a bacterial adaptive immune mechanism, has emerged as a revolutionary tool in genome editing and molecular diagnostics. This review highlights recent advancements in engineering CRISPR/Cas systems to improve specificity in nucleic acid detection, particularly in single-base differences analysis. Mainly focus on Cas protein engineering (e.g., structure-guided mutagenesis, directed evolution) and guide RNA (gRNA) optimization (e.g., mismatch introduction, chemical modifications). Integration of artificial intelligence tools, such as AlphaFold3 for structural prediction and machine learning for guide RNA design, may accelerate CRISPR/Cas system optimization. Despite progress, challenges persist in balancing specificity with efficiency and translating these technologies into clinical practice. By bridging computational innovation with experimental validation, CRISPR/Cas systems are poised to advance portable, scalable molecular diagnostics for precision medicine.

Early diagnosis of Alzheimer's disease (AD) is challenging due to the limitations of current biomarker detection methods. A customizable SERS-based aptasensor platform is presented that combines aptamer-functionalized gold nanoparticles (AuNPs) with machine learning (ML) algorithms for rapid and sensitive tau protein quantification, a key biomarker for AD. Through systematic evaluation of nanoprobes conjugated with four different tau-specific aptamer sequences, two aptamer configurations, named AT and BT, are identified as optimal candidates, demonstrating enhancement factors (EFs) of 2.12 × 10³ and 1.82 × 10³, respectively. This approach enables label-free detection within 30 min and integrates Random Forest (RF) and Convolutional Neural Network (CNN) models for concentration prediction of unknown samples. The RF models achieve remarkable accuracy with R² values of 0.998 for AT and 0.9999 for BT configurations, while the CNN models demonstrate strong performance with R² values of 0.968 (AT) and 0.986 (BT). The platform achieves a detection limit of 100 pM, well within the clinically relevant ranges. This label-free approach offers advantages in terms of rapid detection time, portability, and potential adaptability to other biomarkers. The integration of direct SERS sensing with ML algorithms for automated concentration prediction represents a promising advancement in biomarker analysis.

Hydrogen peroxide (H₂O₂) is an important small metabolite often quantified with commercially available multistep fluorescence-based assays. A new microtiter plate (MTP)-based platform that allows a rapid, one-step assay with a ratiometric readout function is developed. Specifically, 10-Acetyl-3,7-dihydroxyphenoxazine (ADHP) in a polyurethane-based hydrogel sensor membrane is embedded. For a ratiometric set-up, the membranes are loaded with polystyrene nanoparticles containing a Cy5-based reference which allowed for the compensation for variations in membrane thickness. These knife-coated µm-thin films are mounted onto bottomless MTPs with double-sided adhesive tape. Optimized membranes provide measurement times of 3 min upon sample addition and a limit of detection (LOD) in phosphate-buffered saline that is 10x lower than that of the ADHP-using Amplex Red commercial kit of 100 nmol L⁻¹ H₂O₂. These ADHP hydrogels can be stored at room temperature for at least 22 months. Horseradish peroxidase (HRP) is nanospotted alone or together with either lactate oxidase or glucose oxidase for the detection of H₂O₂, lactate, and glucose, respectively. With 50 v% glycerol as cryoprotectant in the spotting solution, the HRP ADHP platform is stable for at least 13 weeks at –20 °C. Enhanced simplicity and comparable performance to multistep assays suggest that the platform can simplify MTP-based assays in the future.

Peptides and proteins with D-amino acids and other stereoisomers in their sequences are now considered to be widespread in different organisms. Their significance is attributed to the altered functions of these molecules, such as having some pathological significance or enhancing biological activity. Only slight shifts in structural and other biophysical parameters make their full characterization and complete distinction technically challenging for traditional tools like mass spectrometry (MS). Ion mobility (IM) spectrometry in conjunction with liquid chromatography (LC) adds an extra dimension to the separation in space as it depends on the mobility of ions, being determined by their overall shape and the orientation of the molecules. Thus, peptide isomers having measurable mobility and collisional cross-section values can thus be resolved by IM-MS. In addition, by combining with tandem MS techniques, IM-MS with adequate conformation-resolving capability is likely to localize the isomerization sites. This review briefly introduces the basic principles of conformation-based chiral separation through LC and capillary electrophoresis, in conjunction with IM-MS for enhanced peptide/protein stereoisomer differentiation, and then comprehensively summarizes the recent advancements in IM-MS-based peptide/protein stereoisomer analysis, focusing on the development of conformation-based chiral separation strategies, including instrumental modifications, chemical modifications, and computational tools.

With the increasing risk of global agricultural instability and the pressing need to enhance crop productivity, monitoring of plant health has become increasingly important. Chemical sensing of agricultural environmental factors and plant signaling molecules has been shown to provide valuable insights into plant growth and development. Recent advances in plant monitoring technologies have seen a shift toward nondestructive, portable, or wearable sensors, which offer advantages over traditional analytical instruments, such as faster detection with real-time monitoring capabilities. However, these emerging forms of chemical sensors have not been widely adopted. This review summarizes recent advancements in plant chemical sensing, highlighting key environmental chemicals and plant biomarkers for detection, sensing materials, and detection mechanisms. Finally, the challenges and outlook of chemical sensors for plant monitoring are discussed. Through the identification of the key challenges, it is hoped to advance the development of nondestructive chemical sensors and facilitate their deployment for in-field plant monitoring.

Knowledge about the molecular structure and interactions of intracellular dyes is important to understand their function and possible effects in the biological environment. Here we discuss vibrational spectra of LysoSensor (LSG), a fluorescent marker for the acidic lysosomal compartment in cells. Raman spectra of the molecule at concentrations typically applied in experiments with cell cultures were obtained by surface-enhanced Raman scattering (SERS) experiments at varying pH values, using biocompatible gold nanoprobes also used in live cell SERS. The signals in the SERS spectrum of LSG were assigned based on spectra collected from its aromatic constituents benzimidazole and naphthalimide under the same conditions. The data indicate a strong pH dependence of the spectra of benzimidazole that is less pronounced in the vibrational signature of the LSG molecule. Despite excitation of the SERS off-resonance with the dye molecule, spectra obtained with the biocompatible wavelength of 785 nm have better sensitivity towards pH-dependent structural changes, due to favorable electromagnetic enhancement of vibrational modes, than when using excitation at 633 nm. The characterization based on SERS will help to understand the interactions of LSG with the cellular environment and with other probes, which will be useful for the design of efficient labels for bioanalysis.