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Single-Cell Photothermal Neuromodulation for Functional Mapping of Neural Networks
摘要： Photothermal neuromodulation is one of the emerging technologies being developed for neuroscience studies because it can provide minimal-invasive control of neural activity in the deep brain with sub-millimeter precision. However, single cell modulation without genetic modification still remains a challenge, hindering its path to the broad application. Here, we introduce a nanoplasmonic approach to inhibit single neural activity with high temporal resolution. Low intensity of near infrared (NIR) was focused at single cell size on gold nanorod (GNR) integrated microelectrode array platform, generating photothermal effect underneath a target neuron for photothermal stimulation. We found that the photothermal stimulation modulates the spontaneous activity of a target neuron in an inhibitory manner. Single neuron inhibition was fast and highly reliable without thermal damage, and it can induce changes in network firing patterns, potentially suggesting their application for in vivo circuit modulation and functional connectomes.
关键词： photothermal effects,local surface plasmonic resonance,neuromodulation,gold nanorod,neuron
更新于2025-09-23 15:23:52
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The Hollow Core Light cage: Trapping Light Behind Bars
摘要： Optical waveguides represent the key element of integrated planar photonic circuitry having revolutionized many fields of photonics ranging from telecommunications, medicine, environmental science and light generation. However, the use of solid cores imposes limitations on applications demanding strong light-matter interaction within low permittivity media such as gases or liquids, which has triggered substantial interest towards hollow core waveguides. Here, we introduce the concept of an on-chip hollow core light cage that consists of free standing arrays of cylindrical dielectric strands around a central hollow core implemented using 3D nanoprinting. The cage operates by an anti-resonant guidance effect and exhibits extraordinary properties such as (1) diffractionless propagation in “quasi-air” over more than a centimetre distance within the ultraviolet, visible and near-infrared spectral domains, (2) unique side-wise direct access to the hollow core via open spaces between the strands speeding up gas diffusion times by at least a factor of 104, and (3) an extraordinary high fraction of modal fields in the hollow section (> 99.9%). With these properties, the light cage can overcome the limitations of current planar hollow core waveguide technology, allowing unprecedented future on-chip applications within quantum technology, ultrafast spectroscopy, bioanalytics, acousto-optics, optofluidics and nonlinear optics.
关键词： integrated photonics,anti-resonance guidance,leaky modes,Hollow core waveguide,3D nanoprinting,spectroscopy
更新于2025-09-23 15:23:52
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Spin density encodes intramolecular singlet exciton fission in pentacene dimers
摘要： The formation of two triplet excitons at the cost of one photon via singlet exciton fission in organic semiconductors can potentially enhance the photocurrent in photovoltaic devices. However, the role of spin density distribution in driving this photophysical process has been unclear until now. Here we present the significance of electronic spin density distribution in facilitating efficient intramolecular singlet exciton fission (iSEF) in π-bridged pentacene dimers. We synthetically modulate the spin density distribution in a series of pentacene dimers using phenyl-, thienyl- and selenyl- flanked diketopyrrolopyrrole (DPP) derivatives as π-bridges. Using femtosecond transient absorption spectroscopy, we find that efficient iSEF is only observed for the phenyl-derivative in ~2.4 ps while absent in the other two dimers. Electronic structure calculations reveal that phenyl-DPP bridge localizes α- and β-spin densities on distinct terminal pentacenes. Upon photoexcitation, a spin exchange mechanism enables iSEF from a singlet state which has an innate triplet pair character.
关键词： spin density,pentacene dimers,charge resonance,intramolecular,singlet exciton fission
更新于2025-09-23 15:23:52
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Deeply subwavelength phonon-polaritonic crystal made of a van der Waals material
摘要： Photonic crystals (PCs) are periodically patterned dielectrics providing opportunities to shape and slow down the light for processing of optical signals, lasing and spontaneous emission control. Unit cells of conventional PCs are comparable to the wavelength of light and are not suitable for subwavelength scale applications. We engineer a nanoscale hole array in a van der Waals material (h-BN) supporting ultra-confined phonon polaritons (PhPs)—atomic lattice vibrations coupled to electromagnetic fields. Such a hole array represents a polaritonic crystal for mid-infrared frequencies having a unit cell volume of 10??λ?3 (with λ? being the free-space wavelength), where PhPs form ultra-confined Bloch modes with a remarkably flat dispersion band. The latter leads to both angle- and polarization-independent sharp Bragg resonances, as verified by far-field spectroscopy and near-field optical microscopy. Our findings could lead to novel miniaturized angle- and polarization-independent infrared narrow-band couplers, absorbers and thermal emitters based on van der Waals materials and other thin polar materials.
关键词： van der Waals material,near-field microscopy,phonon-polaritonic crystal,mid-infrared,hexagonal boron nitride,Bragg resonance
更新于2025-09-23 15:23:52
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Ultrasensitive detection of miRNA with an antimonene-based surface plasmon resonance sensor
摘要： MicroRNA exhibits differential expression levels in cancer and can affect cellular transformation, carcinogenesis and metastasis. Although fluorescence techniques using dye molecule labels have been studied, label-free molecular-level quantification of miRNA is extremely challenging. We developed a surface plasmon resonance sensor based on two-dimensional nanomaterial of antimonene for the specific label-free detection of clinically relevant biomarkers such as miRNA-21 and miRNA-155. First-principles energetic calculations reveal that antimonene has substantially stronger interaction with ssDNA than the graphene that has been previously used in DNA molecule sensing, due to thanking for more delocalized 5s/5p orbitals in antimonene. The detection limit can reach 10 aM, which is 2.3–10,000 times higher than those of existing miRNA sensors. The combination of not-attempted-before exotic sensing material and SPR architecture represents an approach to unlocking the ultrasensitive detection of miRNA and DNA and provides a promising avenue for the early diagnosis, staging, and monitoring of cancer.
关键词： surface plasmon resonance,biosensor,antimonene,cancer diagnosis,miRNA detection
更新于2025-09-23 15:23:52
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Application of metasurfaces in the design of performance-enhanced low-profile antennas
摘要： This paper presents a review of metasurface-based antennas conducted at the Microwave Communication Laboratory (MCL) of Ajou University in the Republic of Korea. In this paper, pro?le miniaturization, bandwidth enhancement, multiband operation, and radiation pattern control of metasurface-based antennas are considered. The paper ?rst presents metasurface-based antennas implemented by placing various radiators on top of the metasurface. It then presents antennas implemented by placing the radiators below the metasurface with and without the ground plane. Metasurface-based antennas are not only able to achieve high ef?ciency with a low pro?le but they are also able to generate extra resonances from the metasurface structures, which signi?cantly enhances the overall performance of the antennas. These additional resonances were utilized in multiband and/or wideband operations. In addition, the design of a planar compact wide-gain-bandwidth metasurface-based antenna and its radiation characteristics are presented at a terahertz (THz) frequency range. The THz antennas were designed with metasurfaces and a planar leaky-wave feeding structure. Finally, the outlook on future research at the MCL for antenna-related work and their applications using metasurfaces is provided.
关键词： surface wave resonance,sequential rotation,crossed dipole,arti?cial magnetic conductor,metamaterial,wideband,circular polarization,leaky-wave,Antenna,array,metasurface
更新于2025-09-23 15:23:52
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G-quadruplex specific dye-based ratiometric FRET aptasensor for robust and ultrafast detection of toxin
摘要： G-quadruplex specific dyes are powerful tools for probing nucleic acid structures. Among nucleic acids, aptamers are of great interest, and widely exploited to construct versatile bioassays. Herein, based on G-quadruplex selective dye, thioflavin T (ThT), for probing the intrinsic structure of aptamers, we proposed a ratiometric fluorescence resonance energy transfer (FRET) aptasensor enabling robust and ultrafast detection of toxin. The binding of target ochratoxin A (OTA) would destruct the G-quadruplex structure of aptamer. It would lead to the detachment of ThT dye from aptamer which diminished the FRET effect between ThT and terminal-labeled dye, thus allowing quantification of OTA via FRET signals. The FRET aptasensor would confer an enhancement of 76.9% of signal to background ratio compared to the ThT-based non-FRET aptasensor. Remarkably, the FRET mechanism would eliminate the signal fluctuation resulted from varied probe concentration, thus benefiting the robustness of the assay. The aptasensor could achieve a detection of limit of 0.38 ng/mL for OTA detection. And the detection of OTA could be finished within 30 s. Besides, the assay was successful in analyzing OTA in coffee and oat samples with recoveries rate of 93.93%–107.59%. Therefore, G-quadruplex specific dye-based probing and FRET method would be a compelling design strategy for aptasensor, and may facilitate their practical application in food safety and environmental screening.
关键词： Fluorescence resonance energy transfer,G-quadruplex specific dyes,Homogeneous analysis,Toxin,Thioflavin T,Aptamer
更新于2025-09-23 15:23:52
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Molecular-beam resonance method with Zeeman-decelerated samples: Application to metastable helium molecules
摘要： We use a multistage Zeeman decelerator to generate slow beams (v ≈ 100 m/s) of translationally cold, spin-polarized metastable a 3Σ+u He2 molecules and perform a precision measurement of their spin-rotation fine structure. The spin polarization results from the elimination of the high-field-seeking J = N spin-rotational component of each rotational level (rotational quantum number N) by the Zeeman deceleration process. By repopulating the J = N component from the J = N ± 1 low-field-seeking components using radio-frequency radiation, we measured the spin-rotation fine structure of 13 rovibrational levels with v = 0, 1 and N = 1–21. The low beam velocity and the resulting long interaction times with the radio-frequency radiation were exploited to determine the transition frequencies with a precision of 300 Hz.
关键词： metastable helium molecules,precision spectroscopy,molecular-beam resonance,Zeeman deceleration,spin-rotation fine structure
更新于2025-09-23 15:23:52
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Influence of the phases structure on the acoustic and optical modes ferromagnetic resonance of FeNi stripe domain films
摘要： FeNi films with different phase structures were prepared by electrodeposition method, and the phase structure of the film was controlled by the composition of the film. The results indicated that the well-defined stripe domain patterns and good magnetic properties of the films were fond of the bcc and bcc + fcc phase structures of the FeNi films. The results of permeability spectra indicated that the acoustic and optical modes of the film could be changed by the direction of the microwave field and stripe domain. FeNi stripe domain films exhibited the different frequency under the two modes, and the acoustic and optical modes of film showed obvious spectra in the bcc and bcc + fcc phases of FeNi films. The results are helpful to the development of the stripe domain optical mode microwave devices.
关键词： Phases structure,Stripe domain,Ferromagnetic resonance,Acoustic and optical modes
更新于2025-09-23 15:23:52
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Surface Plasmon Resonance Based Highly Selective Fiber Optic Dopamine Sensor Fabricated Using Molecular Imprinted GNP/SnO <sub/>2</sub> Nanocomposite
摘要： Fabrication and characterization of a highly selective fiber optic surface plasmon resonance-based dopamine sensor using molecular imprinted graphene nanoplatelets/tin oxide (SnO2) nanocomposite have been reported. The synthesis of sensing layer has been carried out using a series of optimizations and morphological studies. The effectiveness of the sensing layer over other possible probe designs has been proved by performing control experiments for a dopamine concentration range covering the suggested level of dopamine for human being. The limit of detection (LOD) of the sensor evaluated is 0.031 μM, which is lower than the LOD values of various dopamine sensors fabricated using different methods. The specificity of the sensor for dopamine has been confirmed by performing experiments using various interferands while the stability and reusability of the sensor probe have been checked by performing experiments repeatedly for a long period of time. Apart from high sensitivity, low LOD, and fast response, the sensor can be used for remote sensing and online monitoring of dopamine.
关键词： surface plasmon resonance,SnO2 nanoparticles,optical fiber sensor,GNP/SnO2 nanocomposite,graphene,Dopamine,molecular imprinting
更新于2025-09-23 15:23:52