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Herein, a label-free single-molecule electrical sensor was first proposed for the ultrasensitive and selective detection of iodide ions in human urine. Single-molecule conductance measurements in different halogen ion solutions via scanning tunneling microscopy break junction (STM-BJ) clearly revealed that I ions strongly affect the stability and displacement distance (Δ) distribution of molecular junctions. Theoretical calculations prove that the specific adsorption of I ions modifies the surface properties and weakens the molecular adsorption. Furthermore, the average conductance peak area versus the logarithm of the I ion concentration has a very good linear relationship in the range of 5 × 10 to 5 × 10 M, with a correlation coefficient of 0.99. This quantitative analysis remains valid in the presence of interfering ions of SO, ClO, Br, and Cl as well as interfering molecules of ascorbic acid, uric acid, dopamine, and cysteine. A cross-comparison of the human urine detection results of this single-molecule electrical sensor with those of the clinical method of As-Ce catalytic spectrophotometry revealed an average difference of 0.9%, which decreased the detection time of 2 h with the traditional method to approximately 15 min. This work proves the promising practical potential of the single-molecule electrical technique for relevant clinical analysis.
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http://dx.doi.org/10.1021/acssensors.4c02025 | DOI Listing |
Nat Commun
September 2025
Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany.
Precise control of spin states and spin-spin interactions in atomic-scale magnetic structures is crucial for spin-based quantum technologies. A promising architecture is molecular spin systems, which offer chemical tunability and scalability for larger structures. An essential component, in addition to the qubits themselves, is switchable qubit-qubit interactions that can be individually addressed.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
September 2025
Institute of Materiobiology, College of Sciences, Shanghai University, Shanghai, 200444, China.
Self-assembled DNA nanostructures have been popularly used to develop DNA-based electrochemical sensors by exploiting the nanoscale positioning capability of DNA origami. However, the impact of the electric field on the structural stability of the DNA origami framework and the activity of carried DNA probes remains to be explored. Herein, we employ DNA origami as structural frameworks for reversible DNA hybridization, and develop a single-molecule fluorescence imaging method to quantify electric field effects on DNA conformation and hybridization properties at the single-molecule level.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
September 2025
Institute of Modern Optics and Center of Single-Molecule Science, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, Nankai University, Tianjin, 300350, China.
Radical coupling reactions have been widely used in the synthesis of complex organic molecules, materials science, and drug research. However, restricted conditions or special catalysts are required to overcome the energy barrier and trigger the coupling reaction efficiently. In this study, we provide experimental evidence that the C─N radical coupling reactions can be significantly accelerated by an oriented external electric field (OEEF) under synchronous UV irradiation without a catalyst.
View Article and Find Full Text PDFJACS Au
August 2025
Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark.
When a small electric bias is applied to a single-molecule junction, current will flow through the molecule via a tunneling mechanism. In molecules with a cyclic or helical structure there may be circular currents, giving rise to a unidirectional magnetic field. Here, we implement the Biot-Savart law and calculate the magnetic field resulting from the ballistic current density for a selection of molecules.
View Article and Find Full Text PDFMicromachines (Basel)
July 2025
School of Physics, Xidian University, Xi'an 710071, China.
The scattering interaction between a circularly polarized Bessel pincer light-sheet beam and a chiral particle is investigated within the framework of generalized Lorenz-Mie theory (GLMT). The incident electric field distribution is rigorously derived via the vector angular spectrum decomposition method (VASDM), with subsequent determination of the beam-shape coefficients (BSCs) pmnu and qmnu through multipole expansion in the basis of vector spherical wave functions (VSWFs). The expansion coefficients for the scattered field (AmnsBmns) and interior field (AmnBmn) are derived by imposing boundary conditions.
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