Analysis & sensing最新文献

At present, two competing hyperpolarization (HP) techniques, dissolution dynamic nuclear polarization (DNP) and parahydrogen (para-H₂) induced polarization (PHIP), can generate sufficiently high liquid state ¹³C signal enhancement for in vivo studies. PHIP utilizes the singlet spin state of para-H₂ to create non-equilibrium spin populations. In hydrogenative PHIP, para-H₂ is irreversibly added to unsaturated precursors, typically in the presence of a homogeneous catalyst. The hydrogenation catalyst plays a crucial role in converting the singlet spin order of para-H₂ into detectable nuclear polarization. Currently, rhodium(I) bisphosphine complexes are the most widely employed catalysts for PHIP, capable of catalyzing the addition of para-H₂ to unsaturated precursors in organic solvents or aqueous media, depending on the ligand. Chiral catalysts enable the stereoselective production of hyperpolarized substrates. Ruthenium(II) piano stool complexes are capable of trans addition and are used to generate hyperpolarized fumarate. However, these catalysts systems are not optimal, and the greatest source of nuclear spin polarization loss is attributed to the mixing of singlet and triplet states of the protons derived from the para-H₂ during the hydrogenation process. Hence, future efforts should focus on enhancing the efficiency and kinetics of these catalysts.

Carbon nano-onions (CNOs) promise to improve the range of applications of carbon materials for electroanalytical applications. In this review, we explore the synthesis, characterization, and electrochemical applications of CNOs. CNO-based sensors present impressive features, including low detection limits in the femtogram per milliliter range, a broad linear detection range spanning up to 7 orders of magnitude, exceptional selectivity, reproducibility, and stability. Synthetic methods and characterization techniques for CNOs were thoroughly examined, shedding light on their pivotal role in biosensing technologies. Comparative analyses with other carbon materials underscore CNOs′ competitive performance, either surpassing or matching many counterparts. Despite their relatively recent integration in biosensing applications, CNOs exhibit comparable or superior results concerning other carbon-based materials. Indeed, the incorporation of CNOs into hybrid nanocomposites has shown promising outcomes, indicating a synergistic potential for future advancements in biosensing technologies. Our review provides a broad approach to the application of CNOs to the field, with emphasis on breakthroughs of the last 5 years.

Biosensors are analytical tools that integrate a biological element with a physicochemical detector in order to quantify the existence or concentration of chemicals, biomolecules, or other biological elements for human health monitoring purposes. Electrochemical techniques for biological analyte detection include the use of electrochemical sensors to identify and quantify the existence and concentration of biological molecules. These techniques are often used because of their high sensitivity, specificity, quick reaction time, and the possibility of being made smaller in size, but still, the research problem in electrochemical-based biosensing largely revolves around improving biosensors′ sensitivity, selectivity, stability, and response time. Borophene, an intriguing and novel substance within the domain of two-dimensional (2D) materials, emerges as a highly promising protagonist in the continuous and dynamic history of nanoscience and nanotechnology. Borophene, characterized by its distinctive electronic, mechanical, and thermal properties, enthralls scientists due to its atomic structure consisting exclusively of boron atoms organized in a honeycomb lattice. In recent years, borophene hybrids and composites have emerged as potentially fruitful avenues for expanding their utility in numerous fields and improving their properties. In addition, borophene and its hybrid systems hold significant potential to overcome the limitations of current electrochemical-based biosensors. By leveraging their unique properties—such as high surface area, chemical versatility, and mechanical strength—these materials can improve biosensors′ limitations. Moreover, the integration of borophene with other materials can further optimize performance, paving the way for advanced and practical biosensing solutions. This perspective presents a synopsis of recent developments in biosensing composites and hybrids based on borophene, including polymers and other nanomaterials. In addition, we emphasized the remarkable characteristics of borophene hybrids, which permit the detection of biological analytes such as proteins, nucleic acids, and small molecules in a sensitive and selective manner. Additionally, a summary of the computational investigations into analyte detection utilizing borophene-based systems has been provided. In a nutshell, we discussed the challenges and future directions in the field, outlining opportunities for further innovation and optimization of borophene-based biosensing platforms.

Here we report a robust G-quadruplex (G4) dimer-guided transmembrane DNA nanovehicle for targeted payload delivery, based on dimeric G4-proximized aptamers that efficiently target transferrin receptors (TfR) over-expressed on cancer cell surface. It enables the cancer-specific delivery of fluorescent G4 ligands and therapeutic drugs for cellular imaging and treatment.

Hyperpolarized magnetic resonance imaging (HP-MRI) has emerged as a powerful tool in molecular imaging, providing in vivo, real-time insights into metabolic pathways without ionizing radiation. Signal Amplification by Reversible Exchange (SABRE) represents a promising hyperpolarization technique, leveraging parahydrogen to enhance MRI signals. In this concept, we delineate the evolution of SABRE and landmark papers that have enabled us recently to produce biocompatible and low-cost hyperpolarized pyruvate within minutes for in vivo metabolic imaging, showcasing SABRE′s potential for preclinical and near-future clinical settings. Looking ahead, with ongoing efforts focused on optimizing polarizer technology and expanding applications beyond pyruvate, we envision SABRE as a key player in the research and application of HP-MRI due to its simplicity and throughput.

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.