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Blu-ray DVD as SERS substrate for reliable detection of albumin, creatinine and urea in urine
摘要： We report here the working of a simple reproducible surface enhanced Raman scattering (SERS) substrate by efficiently guiding localized plasmon resonance (LSPR) field of gold nanoparticles (AuNPs) through trapping it in the nano channels of a blu-ray digital versatile disc (BRDVD). SERS based sensing of the designed substrate has been performed. The trapped AuNPs in the channel of the BRDVD generate guided mode resonance (GMR) field and the photon lifetime of the coupled em field in the channel increases which accounts for overall enhancement of the local field intensity. These two factors are primarily responsible for enhancement of the scattered Raman signal from the substrate. The proposed SERS substrate yields reasonably stable signal intensity over a period of 45 days. With the designed substrate Raman signal intensities of three clinically important chemicals namely albumin, creatinine and urea in urine have been measured and quantified reliably. The minimum concentration of albumin, creatinine and urea which can be measured by Raman spectrometer are 0.1 μg/mL, 0.2 μg/mL and 0.6 μg/mL respectively. These values are well below the normal range and thus meet the requirement of detection and analysis of these chemicals for different clinical purposes.
关键词： SERS,Nanochannel,LSPR,BRDVD,Guided mode resonance,Urine sample
更新于2025-09-23 15:23:52
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Quantification of Vortex Generation Due to Non-Equilibrium Electrokinetics at the Micro/Nanochannel Interface: Spectral Analysis
摘要： We report on our investigation of a low Reynolds number non-equilibrium electrokinetic ?ow in a micro/nanochannel platform. Non-equilibrium electrokinetic phenomena include so-called concentration polarization in a moderate electric ?eld and vortex formation in a high electric ?eld. We conducted a spectral analysis of non-equilibrium electrokinetic vortices at a micro/nanochannel interface. We found that periodic vortices are formed while the frequency varies with the applied voltages and solution concentrations. At a frequency as high as 60 Hz, vortex generation was obtained with the strongest electric ?eld and the lowest concentration. The power spectra show increasing frequency with increasing voltage or decreasing concentration. We expect that our spectral analysis results will be useful for micromixer developers in the micromachine research ?eld.
关键词： spectral analysis,concentration polarization,micromixer,Vortex generation,electrokinetics,micro/nanochannel
更新于2025-09-23 15:21:21
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Two-state switchable plasmonic tweezers for dynamic manipulation of nano-objects
摘要： In this work, we present a plasmonic platform capable of trapping nano-objects in two different spatial configurations. The switch between the two trapping states, localized on the tip and on the outer wall of a vertical gold nanochannel, can be activated by varying the focusing position of the excitation laser along the main axis of the nanotube. We show that the switching of trapping site is induced by changes in the distribution of the electromagnetic field and of the trapping force. The 'inner' and 'outer' trapping states are characterized by a static and a dynamic behavior respectively, and their stiffness is measured by analyzing the positions of the trapped specimens as a function of time. In addition, we demonstrate that the stiffness of the static state is high enough to trap particles with diameter as small as 40 nm. These results show a simple, controllable way to generate a switchable two-state trapping regime, which could be used as a model for the study of dynamic trapping or as a mechanism for the development of nanofluidic devices.
关键词： gold nanochannel,nano-objects,plasmonic platform,trapping force,nanofluidic devices,electromagnetic field,dynamic behavior,trapping states
更新于2025-09-23 15:21:01
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Ultrasensitive and Label-Free Detection of Cell Surface Glycan Using Nanochannel-Ionchannel Hybrid Coupled with Electrochemical Detector
摘要： In this work, asymmetric nanochannel-ionchannel of porous anodic alumina (PAA) coupled with electrochemical detector was used for sensitive and label-free detection of cell surface glycan. The amplified ionic current caused by array nanochannels as well as the ionic current rectification (ICR) caused by asymmetric geometry endows PAA with sensitive ionic current response. Functionalized with the special molecular probe, the constructed nanofluidic device can be used for selective recognition and detection of glycan in real-time and label-free format. In addition, due to the subnanosize of ionchannels, the probe immobilization and glycan recognition is carried out on the outer surface of PAA, avoiding the blockage of PAA nanochannel by samples, which promises the reproducibility and accuracy of the present method toward bioanalysis. Results show that the glycan concentration ranging from 10 fM to 10 nM can be successfully detected with a detection limit of ~10 aM, which is substantially lower than most previous works. The designed strategy provides a valuable platform for sensitive and label-free detection of cell surface glycan, which acts as a promising candidate in pathological research and cancer diagnosis.
关键词： porous anodic alumina,ionic current rectification,cell surface glycan,nanochannel-ionchannel hybrid,nanofluidics
更新于2025-09-23 15:19:57
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Fabrication and Measurement of a Suspended Nanochannel Microbridge Resonator Monolithically Integrated with CMOS Readout Circuitry
摘要： We present the fabrication and characterization of a suspended microbridge resonator with an embedded nanochannel. The suspended microbridge resonator is electrostatically actuated, capacitively sensed, and monolithically integrated with complementary metal-oxide-semiconductor (CMOS) readout circuitry. The device is fabricated using the back end of line (BEOL) layers of the AMS 0.35 μm commercial CMOS technology, interconnecting two metal layers with a contact layer. The fabricated device has a 6 fL capacity and has one of the smallest embedded channels so far. It is able to attain a mass sensitivity of 25 ag/Hz using a fully integrable electrical transduction.
关键词： nanochannel,NEMS,suspended channel,resonators,CMOS-NEMS
更新于2025-09-10 09:29:36
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Nanochannel-Ionchannel Hybrid Device for Ultrasensitive Monitoring of Biomolecular Recognition Events
摘要： We propose an in-situ and label-free method for detection of biomolecular recognition event using nanochannel-ionchannel hybrid device integrated with an electrochemical detector. The aptamer is first immobilized on the outer surface of the nanochannel-ionchannel hybrid. Its binding with target thrombin in solution considerably regulates the mass transfer behavior of the device owing to the varied surface charge density and effective channel size. Using the electrochemical detector, the changed mass transport property can be in real-time monitored, which enables in-situ and label-free detection of thrombin-aptamer recognition. The solution pH has a significant influence on the detection sensitivity. Under optimal pH condition, the detection limit as low as 0.22 fM thrombin can be achieved, which is much lower than most reported work. The present nanofluidic device provides a simple, ultrasensitive and label-free platform for monitoring the biomolecular recognition events, which would hold great potential in exploring the biomolecules functions and reaction mechanism in the living systems.
关键词： nanofluidic,electrochemical detector,thrombin,nanochannel-ionchannel hybrid,biomolecular recognition
更新于2025-09-04 15:30:14