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- 实验方案
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Electro-plasmonic nanoantenna: A nonfluorescent optical probe for ultrasensitive label-free detection of electrophysiological signals
摘要： Harnessing the unprecedented spatiotemporal resolution capability of light to detect electrophysiological signals has been the goal of scientists for nearly 50 years. Yet, progress toward that goal remains elusive due to lack of electro-optic translators that can efficiently convert electrical activity to high photon count optical signals. Here, we introduce an ultrasensitive and extremely bright nanoscale electric-field probe overcoming the low photon count limitations of existing optical field reporters. Our electro-plasmonic nanoantennas with drastically enhanced cross sections (~104 nm2 compared to typical values of ~10?2 nm2 for voltage-sensitive fluorescence dyes and ~1 nm2 for quantum dots) offer reliable detection of local electric-field dynamics with remarkably high sensitivities and signal–to–shot noise ratios (~60 to 220) from diffraction-limited spots. In our electro-optics experiments, we demonstrate high-temporal resolution electric-field measurements at kilohertz frequencies and achieved label-free optical recording of network-level electrogenic activity of cardiomyocyte cells with low-intensity light (11 mW/mm2).
关键词： label-free,electrophysiological signals,ultrasensitive detection,optical probe,electro-plasmonic nanoantenna
更新于2025-09-19 17:13:59
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Perylenetetracarboxylic Dianhydride and Aniline Assembled Supramolecular Nanomaterial with Multi-color Electrochemiluminescence for Highly Sensitive Label-free Immunoassay
摘要： Most electrochemiluminescence (ECL) studies were focused on the single emission of luminophore, which was severely limited the development of multi-color ECL fundamental theory and applications. Herein, we prepared a multi-color ECL supramolecular nanomaterial self-assembled by 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and aniline (An) through hydrogen bonding. This PTCDA-An supramolecular nanomaterial simultaneously produced multi-color emission peaked at 486, 692 and 760 nm with K2S2O8 as coreactant. And the multi-emissions were assigned to excitated PTCDA monomer (486 nm), H-dimer (692 nm) and J-dimer (760 nm). The simultaneously increased dual-color ECL intensity significantly enhanced the total ECL intensity of PTCDA-An. And this high efficient ECL nanomaterial was further used as ECL platform to construct label-free immunosensor for tumor markers carcinoembryonic antigen (CEA) detection. The total ECL intensity of immunosensor exhibited a sensitive decrease due to the simultaneously decreased ECL of multi-emissions. And this immunosensor exhibited wide linear range from 1 pg mL-1 to 10 μg mL-1 with low detection limit of 0.23 pg mL-1. Multi-color ECL from the same luminophore PTCDA in this work also provided a new perspective for multi-color ECL biomaterial’s design.
关键词： supramolecular nanomaterial,multi-color ECL,electrochemiluminescence,aniline,PTCDA,CEA detection,label-free immunosensor
更新于2025-09-19 17:13:59
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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Fabrication of Cavity-Sealed Optical Interferometric Surface Stress Biosensor by thin Film Transfer Technique
摘要： We developed a surface stress sensor based on a MEMS Fabry-Perot interferometer with cavity-sealed structure by technique of nanometer-thick parylene sheet for highly sensitive label-free biosensing. The proposed MEMS interferometer can measure the membrane deflection caused by target molecule adsorption as the spectral shift. The proposed cavity-sealed optical interferometer can prevent physical adsorption to the backside of membrane and refractive index drift in the cavity, leading to improvement of sensitivity. We successfully obtained the spectral shift of 77 nm in 10 minutes with the color change associated with the antigen-antibody reaction with a concentration of 1 ng/ml, which improved by 16.7-fold compared with the conventional sensor.
关键词： MEMS biosensor,Surface stress sensor,label-free biosensing,film transfer technique,Fabry-Perot interferometer
更新于2025-09-16 10:30:52
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Low-cost and highly accessible technology based on radially polarized beam-excited plasmonic microfiber for label-free Raman detection
摘要： A low-cost and highly accessible method for high sensitivity label-free Raman spectroscopy based on a cylindrical metalized microfiber internally excited via a radially polarized beam (RPB) has been developed. A silver (Ag)-pyramid coated microfiber was designed to be matched with the RPB. Simulation results show that the enhancement of the electric-field intensity of the cylindrically metalized microfiber excited by the RPB can reach a factor of 2.5 × 103, which is much higher than that of linearly polarized beam (LPB) excitation. In experiments, the RPB is directly generated in the optical fiber by converting the LPB to an RPB using electrically controllable, low cost acoustic-optical technology. An Ag-pyramid coated microfiber with ～9.6 μm diameter was prepared using a simple Ag-mirror reaction. The Raman intensity for malachite green (MG) detected by the Ag-pyramid coated microfiber under RPB excitation was 5 times stronger than that under LPB excitation. The Raman sensitivity for MG in the case of RPB excitation was as low as 10?10 M, a concentration level which was not detectable for LPB excitation. The sensor system gave high repeatability and reliability and should find application in high sensitivity label-free detection in optical sensing with the advantages of low-cost and ease of operation.
关键词： low-cost,label-free Raman spectroscopy,radially polarized beam,highly accessible,plasmonic microfiber
更新于2025-09-16 10:30:52
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Plasmonic Contrast Imaging Biosensor for the Detection of H3N2 Influenza Protein-Antibody and DNA-DNA Molecular Binding
摘要： We report a plasmonic contrast imaging biosensor. It measures the intensity difference between the p- and s-polarization images at plasmonic excitation. At plasmonic resonance, only the p- polarization light is excited, while s-polarization light remains the same. Image intensity subtraction between both polarizations can eliminate common system noise and enhance sensor resolution. In refractive index measurements, the sensor resolution was found to be 4.36 × 10-7 RIU. The plasmonic contrast imaging sensor has further been demonstrated for H3N2 influenza antibody detection and DNA-DNA molecular binding detections. The detection limit was found to be 8.6nM (320 ng mL-1) for H3N2 influenza antibodies. This value is 56% and 216% better than the detection limit reported for influenza antibody detection with commercial Biacore systems. A computer control device prototype has further been developed based on the optical design, which is ready for various bio-molecular binding detections.
关键词： Label free,DNA,SPR imaging,Plasmonic biosensor,Resonator,Influenza
更新于2025-09-16 10:30:52
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Polymer-fiber-coupled field-effect sensors for label-free deep brain recordings
摘要： Electrical recording permits direct readout of neural activity but offers limited ability to correlate it to the network topography. On the other hand, optical imaging reveals the architecture of neural circuits, but relies on bulky optics and fluorescent reporters whose signals are attenuated by the brain tissue. Here we introduce implantable devices to record brain activities based on the field effect, which can be further extended with capability of label-free electrophysiological mapping. Such devices reply on light-addressable potentiometric sensors (LAPS) coupled to polymer fibers with integrated electrodes and optical waveguide bundles. The LAPS utilizes the field effect to convert electrophysiological activity into regional carrier redistribution, and the neural activity is read out in a spatially resolved manner as a photocurrent induced by a modulated light beam. Spatially resolved photocurrent recordings were achieved by illuminating different pixels within the fiber bundles. These devices were applied to record local field potentials in the mouse hippocampus. In conjunction with the raster-scanning via the single modulated beam, this technology may enable fast label-free imaging of neural activity in deep brain regions.
关键词： light-addressable potentiometric sensors,polymer fibers,deep brain recordings,label-free,field-effect
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - Seoul, Korea (South) (2019.1.27-2019.1.31)] 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - All-Metal Plasmonic Metamaterials for Structure Color and as Colorimetric Biosensors
摘要： Colorimetric and label-free plasmonic biosensors, relying on localized surface plasmon resonance (LSPR) on metallic subwavelength structures, have significant potential for many application areas such as clinical diagnosis and environmental monitoring detection by simple instrumentation or even naked eye. In this paper, we present a high-performance colorimetric and label-free plasmonic biosensors, consisting of an array of three-dimensional all-metal nano-cavities. The nanostructures, composed of a top array of gold disk, aluminum pillar and bottom gold reflection film, are similar to metal-insulator-metal and the insulating layer is air cavities that are easy to be filled with other gaseous or liquid dielectric. Therefore, the analytes could permeate into the nano-scale cavities and enable strong light-matter interactions there. The sensor shows significant color difference with small refraction index changes and the sensitivity reaches 683.5 nm/RIU. Moreover, when a monomolecular layer of Dithiobis(succinimidyl propionate) (DSP) was bonded to the surface of the nanostructure, the color of the metamaterials change from blue to green back. The metamaterials will offer great potential for detection and studies of binding events between the target analyte and its corresponding receptor.
关键词： LSPR,label-free,metamaterials,colorimetric,plasmonic biosensors
更新于2025-09-12 10:27:22
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Label-Free Super-Resolution Imaging of Transparent Dielectric Objects Assembled on Silver Film by a Microsphere-Assisted Microscope
摘要： In optical microscopy, label-free imaging transparent dielectric objects with sub-wavelength features is still a challenge. We propose a method to super-resolution image a label-free transparent periodic object using the microsphere-assisted bright-field microscope. A two-dimensional array of label-free hexagonally close-packed polystyrene (PS) nanoparticles with a diameter of 250 nm assembled on a silver film coated glass slide can be discerned by coupling a classical optical microscope with a 30-μm-diameter BaTiO3 glass (BTG) microsphere. However, when the PS nanoparticle array with the same diameter is assembled on either a glass slide or a high-reflectance dielectric multilayer coated glass slide, it cannot be resolved. We propose that period plasmonic near-field illumination is generated due to the excitation of surface plasmon polarition modes on periodically structured interfaces. More high-frequency information of the object is coupled into the BTG microsphere lens, resulting in the improvement of imaging resolution.
关键词： transparent dielectric objects,surface plasmon polarition modes,microsphere-assisted microscope,label-free imaging,super-resolution
更新于2025-09-12 10:27:22
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PLASMONIC DIFFRACTION FIELD PATTERN IMAGING COULD RESOLVE ULTRA-SENSITIVE BIO-INFORMATION
摘要： Subwavelength nanohole arrays have been very attractive for label-free biosensing applications as they offer simplicity and flexibility in read-out scheme. Recently, platforms employing imaging-based devices integrated to custom-made light sources and plasmonic nanohole array substrates have been proposed as strong candidates to increase throughput by allowing simultaneous evaluation of binding interactions. Despite their high-throughput and multiplexed nature, these platforms dramatically suffer from sensitivity compared to classical spectrometer-based systems. In this article, we introduced a highly sensitive and plasmonic imaging-based platform that can work with very low analyte concentrations. The system employs a tunable optic filter integrated to a CMOS camera that records diffraction intensity patterns of the transmitted light from a plasmonic biochip composed of periodic nanohole arrays. Monitoring diffraction field intensity variations that correspond to transmission values at different wavelengths within the spectrum, we have successfully reconstructed the transmission spectrum of nanohole arrays. Using bulk solutions, we achieved spectral shifts within the reconstructed spectrum that yields refractive index sensitivities very close to the one calculated from the original spectrum obtained with a spectrometer. Similarly, we showed that our platform yields spectral shift amounts very close to the original one upon the attachment of protein mono- and bilayers. By monitoring plasmonic diffraction field intensity images, created through a very sharp illumination light source overlapping with the plasmonic mode of interest, we experimentally achieved sub-1 ng/mL limit-of-detection. Integrating the plasmonic biochip to a microfluidic chamber, we could monitor protein binding kinetics and determined the associated binding parameters very close to the ones obtained through the classical spectrometer-based analyses. Simultaneously monitoring multiple sensing spots in real-time within the same plasmonic biochip, we demonstrated the high-throughput capability of our plasmonic imaging-based technique. Our results showed the possibility of developing plasmonic read-out platforms that could provide high-throughput and multiplexed biosensing without losing sensitivity when integrating large-scale plasmonic chips with multiple sensing locations to imaging-based devices.
关键词： Nanohole arrays,Plasmonics,Nanofabrication,Diffraction Field Monitoring,Label-free biosensing
更新于2025-09-12 10:27:22
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A Design of Microfluidic Chip with Quasi-Bessel Beam Waveguide for Scattering Detection of Label-Free Cancer Cells
摘要： Light scattering detection in micro?uidic chips provides an important tool to identify cancer cells without any label processes. However, forward small-angle scattering signals of cells, which are related to their sizes and morphologies, are hard to be detected accurately when scattering angle is less than 11(cid:3) in micro?uidic chips by traditional lighting design due to the in?uence of incident beam. Therefore, cell’s size and morphology being the golden standard for clinical detection may lose their ef?cacy in recognizing cancer cells from healthy ones. In this article, a novel lighting design in micro?uidic chips is put forward in which traditional incident Gaussian beam can be modulated into quasi-Bessel beam by a microprism and waveguide. The quasi-Bessel beam’s advantages of nondiffraction theoretically make forward scattering (FS) detection less than 11(cid:3) possibly. Our experimental results for peripheral blood lymphocytes of human beings and cultured HeLa cells show that the detection rates increase by 47.87% and 46.79%, respectively, by the novel designed micro?uidic chip compared to traditional Gaussian lighting method in micro?uidic chips.
关键词： label free,scattering detection,micro?uidic chip,quasi-Bessel beams
更新于2025-09-12 10:27:22