Analysis & sensing最新文献

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.

Many pharmacologically relevant drug targets are located inside cells, requiring small-molecule therapeutics to penetrate the plasma membrane faster than they are metabolically inactivated or expelled by efflux pumps. Accurate measurement of intracellular concentrations is crucial for correlating biochemical potency with cellular efficacy and optimizing ligands. Despite the critical importance of this metric, current methods for quantifying intracellular levels of nonfluorescent small molecules are technically demanding and limited in throughput, significantly restricting the ability of medicinal chemists to readily and routinely measure cellular drug concentration. Here, we introduce a straightforward, high-throughput time-resolved Förster resonance energy transfer assay platform based on CoraFluor technology, a class of highly luminescent terbium complexes, to readily quantify the abundance of biologically active small molecules in whole cell lysates. Our approach conceptually extends existing homogeneous ligand displacement assays and does not require any additional reagents or equipment, enabling the comprehensive biochemical and cellular characterization of small-molecule ligands.

This study focuses on the synthesis, characterization, and sensing capabilities of liquefied petroleum gas (LPG) using 5% and 10% silver-doped zinc ferrite thin films under ambient conditions. A highly efficient sensor for LPG concentrations below the lower explosive limit (LEL) has been developed using Ag decorated on a ZnFe₂O₄ surface. The ZnFe₂O₄, 5% Ag-ZnFe₂O₄, and 10% Ag-ZnFe₂O₄ sensing films are meticulously prepared utilizing a spin coater and subsequently characterized through various techniques to explore the parameters of significance, including surface morphology, porosity, chemical bonding, optical band gap, and crystallinity. Among the synthesized materials, the 10% Ag-ZnFe₂O₄ demonstrates exceptional porosity, specific surface area, and uniformity, due to its faceted surface morphology. The developed 10% Ag-ZnFe₂O₄ film-based sensor exhibits a rapid response to LPG concentrations at room temperature, attaining a peak response of 2.55 when subjected to exposure of 2000 ppm of LPG. The durations for response and recovery were ≈15 and 68 s, respectively. The limit of detection of ZnFe₂O₄, 5% Ag-ZnFe₂O₄%, and 10% Ag-ZnFe₂O₄ sensors are observed to be ≈288, 220, and 205 ppm, respectively. The findings underscore the significance of an optimized 10% Ag-ZnFe₂O₄ sensor for efficient and economical LPG detection in residential and commercial environments.

The deterioration of aquatic ecosystems now ranks among the most urgent planetary challenges, with cascading effects on species survival, human welfare, and socioeconomic progress. Surface-enhanced Raman scattering (SERS), owing to its exceptional sensitivity, molecular fingerprinting capability, and rapid response, has become a powerful analytical technique for detecting water pollutants. This article provides a comprehensive summary of recent improvements in the use of SERS for detecting water pollutants. To begin with, SERS substrates are categorized into three major types—metallic, semiconductor, and composite—based on their distinct enhancement mechanisms. Building upon this classification, their use in detecting a wide range of aquatic pollutants, including heavy metal ions, pathogenic microorganisms, organic compounds, and micro/nanoplastics, is examined. Strategies for substrate design, sensitivity enhancement methods, and practical detection performance in real-world samples are also systematically reviewed. Finally, the review discusses challenges in applying SERS to water pollution monitoring and outlines future research directions. This review aims to provide valuable insights for advancing SERS-based strategies in environmental monitoring and promoting their practical application in water pollution detection.

Fluoride ions improve dental health, but their excessive intake has adverse effects on the human body. Hence, a simple system for sensing fluoride ions is required. Herein, a simple colorimetric sensing system for fluoride ions is reported, together with the detailed investigation of its sensing mechanism. The azo dye-based chemosensors are designed bearing a boron ester moiety and a hydroxyl group at the ortho- and para-positions of the azo moiety, respectively (ortho-azophenylboronic acid esters, azoB-esters). A series of pinacol- and 1,8-naphtalenediamine-protected azoB-esters (azoB(pin)-1 − azoB(pin)-4, and azoB(dan)-1 − azoB(dan)-3, respectively) are synthesized. Single-crystal X-ray crystallography, UV–vis absorption spectroscopy, and ¹¹B nuclear magnetic resonance studies reveal that all azoB-esters, except azoB(pin)-1, are mainly present as trigonal boronic acid species in tertiary butanol and aprotic solvents. Only azoB(pin)-1 shows the presence of a solvent-inserted species in protic solvents, resulting in an additional absorption band in the longer wavelength region. The azoB-esters show significant changes in their absorption spectra in response to fluoride ions in tertiary butanol, with some also displaying dramatic colorimetric changes detectable by the naked eye. For example, when azoB(pin)-2 is used to sense fluoride ions in surfactant-containing water, a visually discernible color change is observed.

Electrochemiluminescence (ECL) is an advanced analytical and sensing technique that offers excellent spatiotemporal controllability, high sensitivity, and wide dynamic detection range. With the rapid development of ECL immunoassays, novel electrochemical materials, and optical detection devices, enhanced ECL systems based on the coreactant pathway have garnered a continued attention. Since the generation of active intermediates from coreactants serves as a pivotal step in the generation of ECL signals, the introduction of coreactant catalysts, materials capable of catalyzing the oxidation or reduction of coreactants to produce active intermediates, has significantly improved the ECL systems and expanded their applications. This review is concerned with some of the most recent and important advances in coreactant catalysts, aiming to comprehend how to rationally design high–performance ECL analytical systems. It starts by presenting a brief introduction on ECL mechanistic pictures and application scenarios. Then the focus is directed toward the catalytic enhancement mechanisms of various coreactant catalysts. Finally, a short perspective and outlook for the future of work is proposed.