Analysis & sensing最新文献

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.

Fluorescent sensor arrays address the limitations of a single sensor by leveraging multiple sensing elements to generate unique response patterns for each of the analyte of interest. This approach has emerged as a powerful tool for identifying and analyzing intricate chemical and biological environments using various multivariate analytical tools such as principal component analysis (PCA), linear discriminant analysis (LDA), and hierarchical cluster analysis (HCA). Nevertheless, the extraction of reliable quantitative information from these arrays presents a greater challenge, primarily due to the complexity associated with managing large datasets using conventional regression methods. In recent years, there has been a notable surge in exploring diverse statistical multivariate techniques and deep learning models (including PCA, LDA, HCA, partial least square regression, support vector regression, Gaussian processes regression, and neural networks) as modern regression tools to handle multidimensional data. These analytical tools facilitate the simultaneous acquisition of both qualitative and quantitative information for various analytes using sensor arrays.

Cardiovascular disease (CVD) remains a major cause of mortality worldwide, and there is an urgent need to develop point-of-care (POC) diagnostic tools for rapid, regular, and on-site monitoring of trace levels of cholesterol in human biological fluids. This work presents a new, reliable, selective, and cost-effective POC sensor for salivary examination of CVD. An interdigital device is utilized for electronic (capacitive) detection of cholesterol using nanostructured Ag@MoO₃-enhanced molecularly imprinted poly(styrene-co-divinylbenzene) in real-time salivary analysis. The formulation of cholesterol-imprinted poly(styrene-co-divinylbenzene), molecularly imprinted polymer (MIP), and the operational frequency of the devices are precisely optimized. The Ag@MoO₃-MIP sensors exhibit a low limit of detection of 0.03 μM and a limit of quantification of 0.1 μM with an impressive sensitivity of 409 nF μM⁻¹ in the linear range of cholesterol concentration 0.1–2.0 μM. Furthermore, the sensor exhibits excellent selectivity for cholesterol, effectively distinguishing it from other interfering analytes like ascorbic acid, creatinine, guanine, uric acid, and glucose. The recovery outcomes of real-time spiked saliva samples are within the range of 85.17–98.19%. The sensor's ability to provide reliable, reproducible, and rapid cholesterol analysis in human saliva highlights its potential for early CVD detection and continuous surveillance, leading to improved patient outcomes and more accessible healthcare solutions.

In this study, sulfur-nitrogen-codoped carbon nanodots (N,S-doped CNDs) are synthesized both in their soluble pristine form and incorporated into aminosilica particles. These materials, are utilized for the fluorometric detection of Hg(II) and Cr(VI). Both the soluble N,S-doped CNDs and the aminosilica/N,S-doped CNDs exhibit two distinct emission spectral bands when the excitation wavelength is varied. The fluorescence of soluble N,S-doped CNDs at λ_ex/λ_em = 390 nm/470 nm is quenched in the presence of both Hg(II) and Cr(VI); however, only Hg(II) quenches the fluorescence at λ_ex/λ_em = 450 nm/553 nm. In contrast, only Cr(VI) quenches the fluorescence of aminosilica/N,S-doped CNDs at λ_ex/λ_em = 380 nm/463 nm, while the fluorescence at λ_ex/λ_em = 440 nm/538 nm remains unaffected. By exploiting the fluorescence quenching behavior of free and aminosilica-embedded N,S-doped CNDs, fluorescence-based probes are developed to selectively detect Hg(II) and Cr(VI). The limits of detection, defined as the concentrations corresponding to a signal-to-noise ratio of 3, are determined to be 0.04 and 0.06 μM for Hg(II) and Cr(VI), respectively. Further investigations reveal distinct quenching mechanisms for each system: the fluorescence quenching effect on N,S-doped CNDs by Hg(II) is attributed to a static mechanism, and the quenching of aminosilica/N,S-doped CNDs by Cr(VI) is ascribed to the inner filter effect.

An imidazolium salt (E)-3-(hydroxy-4-(((2-hydroxyphenyl) imino) methyl) benzyl)-1-methyl-1 H-imidazol-3-ium chloride (HBIm) is synthesized and evaluated for its fluorescence behavior toward metal ions. The probe detected Al³⁺ and As³⁺ ions when excited at 326 nm in an aqueous medium. The nonfluorescent HBIm exhibited a “turn-on” fluorescence response upon being treated with Al³⁺ (λ_em = 510 nm) and As³⁺ (λ_em = 499 nm) ions due to the chelation-enhanced fluorescence effect. The detection limits for Al³⁺ and As³⁺ are low and are found to be 0.38 and 2.37 nM, respectively. Furthermore, the binding constants for these ions are significantly high, 1.59 × 10⁵ M⁻¹ for Al³⁺ and 3.54 × 10⁴ M⁻¹ for As³⁺. The binding mechanism between HBIm and Al³⁺ and As³⁺ ions is supported by various techniques, including ESI-MS, Job's plot, ¹H NMR, X-ray photoelectron spectroscopy, SEM-EDS, and density functional theory studies. The reversibility experiments are conducted using EDTA ions to develop the corresponding logic gates. HBIm has the potential to detect Al³⁺ and As³⁺ ions in real samples, such as plant cells, tissues, and water samples.

Industrial wastewater release of dyes poses serious environmental and health risks when introduced into natural water systems. Herein, a cyclodextrin-based polymer sensor (Ech-CDP) is developed for real-time, visible detection of harmful methylene blue (MB) and methyl orange (MO) dyes in distilled and contaminated natural water samples. The sensor works through a competitive host-guest mechanism between sodium dodecyl sulphate (SDS) and Ech-CDP, altering liquid crystal alignment. Initially, SDS induces homeotropic ordering, which shifts to a tilted state upon binding with Ech-CDP. The presence of MB or MO displaces SDS, reverting the alignment and causing a visible bright-to-dark transition under polarizers. The sensor exhibits high selectivity, with detection limits of 0.03 mM for MB and 0.05 mM for MO in aqueous solutions, and 0.08 mM for MB and 0.26 mM for MO in real water samples, remains effective for 3 days, and is unaffected by pH variations between 4.8 and 9.1. Additionally, the sensor demonstrates an on–off switching capability, suggesting potential applications for molecular logic gates and advancing environmental monitoring techniques in dye-polluted waters.