Analysis & sensing最新文献

Acetylene (C₂H₂), as an important characteristic gas in transformer fault diagnosis, should be accurately detected and effectively distinguished from other dissolved gases (H₂, CH₄, C₂H₆, C₂H₄, CO, CO₂), which is crucial to determine whether the fault occurs and the fault type, but also faces challenges now. The rational design and employment of rare earth and noble metals are expected to address this issue. In this work, SnO₂-3 at% Sm₂O₃-1 at% PdO based MEMS gas sensor was prepared to achieve high performance detection of C₂H₂ which has a response value of 56 to 50 ppm C₂H₂, response/recovery time of 2 s/136 s, lower detection limit of 1 ppm, power consumption of 15.5 mW, and weak cross sensitivity to other transformer fault characteristic gases. Lewis acids and bases theory was used to explain the reason why rare earth Sm is a benefit element to improve selectivity to C₂H₂. The formation of oxygen vacancies and hetero junctions was used to explain the increased sensitivity of the material. This study proved the feasibility of rare earth and noble metals as potential additives to enable advanced gas-sensitive materials for highly selective transformer fault characteristic gas C₂H₂ detection.

Metronidazole and nimorazole are antibiotics of a nitroimidazole group which also may be potentially utilized as hypoxia radiosensitizers for the treatment of cancerous tumors. Hyperpolarization of ¹⁵N nuclei in these compounds using SABRE-SHEATH (Signal Amplification By Reversible Exchange in SHield Enables Alignment Transfer to Heteronuclei) approach provides dramatic enhancement of detection sensitivity of these analytes using magnetic resonance spectroscopy and imaging. Methanol-d₄ is conventionally employed as a solvent in SABRE hyperpolarization process. Herein, we investigate SABRE-SHEATH hyperpolarization of isotopically labeled [¹⁵N₃]metronidazole and [¹⁵N₃]nimorazole in nondeuterated methanol and ethanol solvents. Optimization of such hyperpolarization parameters as polarization transfer magnetic field, temperature, parahydrogen flow rate and pressure allowed us to obtain an average ¹⁵N polarization of up to 7.2–7.4 % for both substrates. The highest ¹⁵N polarizations were observed in methanol-d₄ for [¹⁵N₃]metronidazole and in ethanol for [¹⁵N₃]nimorazole. At a clinically relevant magnetic field of 1.4 T the ¹⁵N nuclei of these substrates possess long characteristic hyperpolarization lifetimes (T₁) of ca. 1 to ca. 7 min. This study represents a major step toward SABRE in more biocompatible solvents, such as ethanol, and also paves the way for future utilization of these hyperpolarized nitroimidazoles as molecular contrast agents for MRI visualization of tumors.

Sensitive and accurate detection of small molecules from complex matrix has aroused increasing interest in many fields, yet remains an open challenge. Recent years have witnessed a considerable advance of aptasensors for diagnostic assay development towards diverse small molecules because aptamer is one of the most powerful classes of molecular receptors with advanced affinity and specificity. Herein, we reviewed the small-molecule aptasensors in the past five years, focusing on the principles to specific applications in clinical diagnosis, food safety, and environmental monitoring. The first introductory section on the development of aptasensors in historical view and its analytical features contextualizes essential health-related small molecules. The second part highlights the basic components of aptasensor and the detection principles of different sensors based on signal output modes. The subsequent part systematically discusses various small-molecule sensing platforms by interfacing aptamers with diverse signal amplification strategies. Finally, challenges and perspectives for improving the aptasensor performance are also discussed. By describing biochemical and analytical procedures, this review highlights the optimal use of aptamers in the detection, quantification, and imaging of important health-related small molecules and presents new insights, technical advances, and engineering strategies for practical applications.

Electrochemical impedance spectroscopy (EIS) is a suitable analytical technique to detect interfacial phenomena and analyte binding at electrode surfaces. In contrast to metallic electrodes, carbon-based electrodes are more suited due to the low cost and the availability of more versatile methods for chemical functionalization. For (bio) sensing, often the Faradaic version of EIS in a three-electrode configuration is used, where a redox-active species is used as a marker. In order to avoid interference due to the redox-active marker with the interfacial interaction, we focus here on the use of non-Faradaic EIS in the absence of any added markers. First, we utilize the sedimentation of silica beads as a model system, which reduces the complexity of the interaction simplifying the interpretation of the measured signals. Moreover, we introduce two improvements. First, impedance measurements are performed in a three-electrode configuration with applied potential as an additional variable, which serves as a handle to optimize the sensitivity. Secondly, we present a time-differential strategy to detect subtle changes and demonstrate that we can consistently follow the sedimentation of beads using the non-Faradaic impedance as a function of the applied potential. Finally, we show a proof-of-principle demonstration for the biosensing of cell attachment on the electrodes in real-time using the proposed technique.

Carbon monoxide (CO), a simple and well-known toxic gas, is a naturally occurring gaseous transmitter that plays a crucial role in the regulation of physiological and pathological processes in living organisms. Usually, the development of various diseases can lead to the dysregulation of CO levels. Interestingly, CO has been shown to exert therapeutic effects in inflammation-related disease models. Fluorescent probes for CO detection have become a vital research field in the past decades owing to their advantages of excellent selectivity, exceptional sensitivity, and real-time in situ detection, which have been employed for the precise detection of CO in cells, tissues, and even living organisms. This paper reviews research advancements in CO fluorescent probes over the last decade, outlines the design concepts and detection mechanisms of relevant fluorescent probes, and provides design guidelines and future development prospects.

Here, we describe for the first time the fabrication of laser-induced graphene (LIG) electrodes on a hybrid substrate composed of sandpaper and polyester. As a proof of concept, the proposed device was used as a voltammetric sensor for tadalafil (TAD) quantification in authentic tablet samples. The electrochemical TAD sensing based on differential pulse voltammetry (DPV) revealed a linear behavior in the concentration range from 25 to 250 μmol L⁻¹(R²=0.99), a limit of detection of ~9.6 μmol L⁻¹, sensitivity of ~0.0048 μA(μmol L⁻¹)⁻¹ and acceptable reproducibility values (RSD≤5.8 %). The DPV responses involving the standard addition method in pharmaceutical samples presented recovery results of TAD ranging from 93 to 108 %. Also, the proposed analytical method offered a suitable green analytical chemistry profile. We successfully demonstrated the fabrication of graphene-like sites and nanoparticles composed of alumina upon a hybrid substrate.

Point-of-care diagnostics relies on optical and electrochemical sensors to develop devices that are both compact and cost-effective. Therefore, the search for new design principles for chemosensors that enable multiple signal outputs is a particularly interesting concept. In this work, we present an unimolecular chemosensor based on cucurbit[7]uril that combines two signal readouts - namely fluorescent and electrochemical signals - in a single chemosensor design. This is achieved by utilizing the tunable fluorescence and the electrochemical properties of the reporter molecule, which depend on whether or not it is engulfed by the cucurbit[7]uril cavity in the absence or presence of the analyte. By setting up an assay using the dual readout chemosensor, illicit drug formulations containing pancuronium bromide or nicotine can be detected at low micromolar concentrations (0–100 μM). This assay is compatible with standard fluorescence plate readers and electrochemical devices, including commercially available screen-printed electrodes. Overall, the chemosensor presented in this study represents a significant advance in the development of cucurbit[7]uril chemosensors, characterized by multimodal detection capabilities. It uniquely combines traditional optical and electrochemical detection methods in a single molecular design.

pH is one of the key parameters in chemistry and impacts almost all chemical and biological processes. Also, within analytical chemistry and sensing, pH plays a critical role. This review underscores the critical role of pH manipulation in overcoming analytical challenges posed by complex sample matrices and dynamic environmental conditions. It explores the available tools to control pH at a local scale and how those are or can be applied to improve sensor performance. We focus on four key areas where pH modulation has been or could be leveraged to advance chemical sensing capabilities: i) sensing alkalinity and buffer capacity, ii) sample pretreatment, iii) sensing pH dependent analytes and iv) reducing biofouling. We analyze existing strategies, but also try to identify unexplored possibilities which may have potential and can be exploited for sensing.

Electrochemical immunosensors have emerged in the last years as outstanding analytical systems for the detection of analytes of clinical interest. As alternative to the traditional enzymatic labels, the use of nanoparticles and especially bimetallic ones has gained increased attention thanks to their advantages related to the higher simplicity, stability and sensitivity offered. Main routes for the detection of such nanoparticle labels are based on i) dissolution of the nanoparticle into the corresponding metal ions followed by voltammetric detection; ii) taking advantage of the electrocatalytic effect of the metals towards secondary reactions; and iii) taking advantage of their electrochemiluminescence properties.

Plant hormones and their receptors play a crucial role in regulating plant growth and adapting to the stress environment. The exploration of interaction between plant hormones and their receptors is significant to comprehend the molecular mechanisms of plant growth and development, the response mechanisms of adaptation to environmental changes, and to optimize the traits and stress-resistance of crops. Since the biosynthesis, transport, and metabolism of hormones in plants are closely relevant to spatio-temporal changes, and their content and distribution are highly dynamic, there is an urgent need for a qualitative and quantitative tool to accurately, real-time, and in situ monitor the dynamic changes of hormones in plants without injury. Fluorescent probes have been widely used in the sensing and imaging of plant hormones and their receptors, due to their high spatio-temporal resolution, high selectivity, non-invasive, high sensitivity, and tailored molecular structures. Here, this paper provides a systematical overview of the research progress in the sensing and imaging of plant hormones and their receptors using fluorescent probes. In addition, the potential prospects and remaining challenges are also discussed to design fluorescent probes with better performance and promote the development of this field.