Analysis & sensing最新文献

5-Methylcytosine (5 mC) is an epigenetic modification that plays several important roles ranging from development to disease progression. Local cytosine methylation is still detected and quantified utilizing bisulfite cytosine to uracil conversion and methylated base counting following PCR. Electrochemical approaches may offer more rapid means to provide this output. Here, small oligomeric DNA sequences from the CD8+ T-cell reporter gene featuring between 0 and 4 5 mC sites were immobilized on Au electrodes via self-assembly. 5 mC content was assayed via square wave voltametric reduction of a di-viologen molecule (C₁₂H₂₅V²⁺C₆H₁₂V²⁺C₁₂H₂₅, V²⁺=4,4’-bipyridyl or viologen) bound to the DNA. 5 mC presence induced subtle structural changes in the oligomers, which could be detected monitoring di-viologen reduction current changes at −0.39 V vs. SCE after exposure to higher ionic strength conditions. Solution phase CD spectroscopy was employed to validate the DNA structural changes occurring at the electrode surface and provide insight into the structural perturbations resulting from 5 mC presence. Overall, this method provides a relatively simple electrochemical 5 mC monitoring approach for small gene sequences based on helical structure.

The expression profiles of intracellular biomarkers hold significance for understanding cellular biological functions and tracking pathological activities. Due to its programmability and biocompatibility, extensive efforts have been devoted to design various kinds of nucleic acid probes for biomarker detection. However, pinpointing a single biomarker could end up in a false positive signal, delaying diagnosis. In this review, we present an overview of current advances in biomarker detection and signal amplification techniques. We highlight strategies for biomarker multiplexing and signal amplification with combination of isothermal approaches. High specificity and sensitivity are the two criteria for a desired probe, as are the challenges encountered by a probe that operates efficiently in biological systems. With higher biomarker identification accuracy, we may be able to move one step closer to precision medicine.

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.