Terahertz Chemical Microscope Research Articles

Terahertz aptasensor for dopamine neurochemical detection

Measuring neurotransmitter levels in the body can identify imbalances and diagnose neurological and psychiatric disorders. Several advanced imaging technologies and electrochemical and optical sensors have been developed for a highly sensitive and selective detection of neurotransmitters. In this study, a terahertz chemical microscope (TCM) for measurement of dopamine levels is proposed. The TCM uses terahertz waves to obtain a label-free chemical reaction on a sensing plate. A DNA aptamer is investigated as a recognition element for detection of dopamine. The measurement mechanism and construction of the terahertz aptasensor are described, providing a potential alternative for neurotransmitter detection.

A Versatile Terahertz Chemical Microscope and Its Application for the Detection of Histamine

Terahertz waves have gained increasingly more attention because of their unique characteristics and great potential in a variety of fields. In this study, we introduced the recent progress of our versatile terahertz chemical microscope (TCM) in the detection of small biomolecules, ions, cancer cells, and antibody–antigen immunoassaying. We highlight the advantages of our TCM for chemical sensing and biosensing, such as label-free, high-sensitivity, rapid response, non-pretreatment, and minute amount sample consumption, compared with conventional methods. Furthermore, we demonstrated its new application in detection of allergic-related histamine at low concentration in buffer solutions.

Detection of Lung Cancer Cells in Solutions Using a Terahertz Chemical Microscope.

Cancer genome analysis has recently attracted attention for personalized cancer treatment. In this treatment, evaluation of the ratio of cancer cells in a specimen tissue is essential for the precise analysis of the genome. Conventionally, the evaluation takes at least two days and depends on the skill of the pathologist. In our group, a terahertz chemical microscope (TCM) was developed to easily and quickly measure the number of cancer cells in a solution. In this study, an antibody was immobilized on a sensing plate using an avidin-biotin reaction to immobilize it for high density and to improve antibody alignment. In addition, as the detected terahertz signals vary depending on the sensitivity of the sensing plate, the sensitivity was evaluated using pH measurement. The result of the cancer cell detection was corrected using the result of pH measurement. These results indicate that a TCM is expected to be an excellent candidate for liquid biopsies in cancer diagnosis.

Visualization of Charge-Transfer Complex for the Detection of 2,4,6-Trinitrotoluene Using Terahertz Chemical Microscope

This study focuses on the visualization of a charge-transfer complex, namely a Meisenheimer complex, for the detection of uncharged 2,4,6-trinitrotoluene (TNT) explosives by developing a terahertz chemical microscope (TCM) imaging system. The organic amine 3-aminopropyltriethoxysilane (APTES) was immobilized on an SiO2-film-coated TCM sensing plate, where it interacted with TNT molecules. The surface electrical potential distribution of TNT, APTES, and the charge-transfer complex was mapped. An electrical potential shift occurred due to the formation of a charge-transfer complex between the electron-rich amino-silane APTES and electron-deficient TNT molecules on the surface of the sensing plate. The electrical imaging and detection of TNT explosives by using the TCM imaging system were demonstrated by measuring the amplitude of the terahertz pulse caused by this electrical potential shift. N-(2-Aminoethyl)-3-aminopropyltrimethoxysilane and N1-(3-trimethoxysilylpropyl)diethylenetriamine were used for further evaluation and comparison of color changes arising from the amine-TNT interactions. The results have shown that TCM imaging is a promising method for the detection of uncharged TNT explosives at a low (sub-parts-per-million) concentration.

Development of impedance measurement of lithium ion batteries electrode using terahertz chemical microscope

AbstractIn recent years, with the spread of electric vehicles, improvement in the performance of lithium ion batteries has been required. Evaluation of the active material is important because the performance of the lithium ion battery is affected by the movement of lithium ions at the electrode active material‐electrolyte interface. In this study, we fabricated a lithium ion battery with the sensing plate, which is a potential sensor, attached to the positive electrode, and evaluated lithium ion battery with a terahertz chemical microscope (TCM). As a result, we succeeded in measuring the potential distribution of the positive electrode during charging and discharging, and the local impedance.

Terahertz Chemical Microscope Imaging System for 2, 4, 6-Trinitrotoluene Detection

In this study, a terahertz chemical microscope (TCM) imaging system was developed for visualization and detection of 2, 4, 6-trinitrotoluene (TNT) explosive. The organic ligand 3-aminopropyltriethoxysilane (APTES) was one-step immobilized on the silicon dioxide (SiO2) film coated TCM sensing plate to interact with TNT molecule. The APTES modified surface was optimized and confirmed by using atomic force microscope. Electrical potential shift was occurred due to the formation of a charge-transfer complex (Meisenheimer complex) between electron-rich amino-silane APTES and electron-deficient TNT molecule on the sensing plate surface. By measuring the terahertz pulse’s amplitude caused by this electrical potential shift using the TCM imaging system, the chemical imaging and detection of TNT explosive were demonstrated. Figure 1

Terahertz imaging technique for monitoring the flow of buffer solutions at different pH values through a microfluidic chip

Polydimethylsiloxane (PDMS)-based mold prepared using a 3D-printed structure is a cost-effective material and tool to fabricate robust microfluidic chips (MCs) without requiring expensive clean room facilities. A capillary-based MC made of PDMS can be attached onto a glass substrate to visualize the chemical reactions in different types of pH buffer solutions (BSs) flowing through microflow channels (MFCs) using terahertz (THz) image sensing technology. In this study, we designed a microfluidic structure with two inlet wells and an outlet well, equipped with a Si:sapphire substrate to visualize the chemical interaction between BSs injected at different pH values (4 and 10) through an MFC. THz imaging maps were captured during the flow of the BSs using a THz chemical microscope, and the fluid dynamics was studied. We determined and plotted the variation in the THz amplitude data with respect to the BS concentration and analyzed the characteristics of the data.

High-sensitivity small-molecule detection of microcystin-LR cyano-toxin using a terahertz-aptamer biosensor.

We demonstrate the rapid and highly sensitive detection of a small molecule, microcystin-LR (MC-LR) toxin using an aptasensor based on a terahertz (THz) emission technique named the terahertz chemical microscope (TCM). The main component of the TCM is the sensing plate, which consists of a thin silicon layer deposited on a sapphire substrate, with a natural SiO2 layer formed on the top of the Si layer. The DNA aptamer is linked to the oxidized top surface of the silicon layer by a one-step reaction (click chemistry) between the DBCO-labeled aptamer and an azido group that binds to the surface. Using density functional theory (DFT) calculations, the number of active sites on the surface has been estimated to be 3.8 × 1013 cm-2. Aptamer immobilization and MC-LR binding have been optimized by adjusting the aptamer concentration and the binding buffer composition. When MC-LR binds with the DNA aptamer, it causes a change in the chemical potential at the surface of the sensing plate, which leads to a change in the amplitude of the THz signal. Compared with other bio-sensing methods such as surface plasmon resonance (SPR), TCM is a rapid assay that can be completed in 15 min (10 min incubation and 5 min data acquisition). Moreover, our results show that the aptamer-based TCM can detect MC-LR with an excellent detection limit of 50 ng L-1, which is 20 times more sensitive compared with SPR measurements of MC-LR.

Electric Potential Distribution on Lithium Ion Battery Cathodes Measured Using Terahertz Chemical Microscopy

A terahertz chemical microscope has been developed to visualize electric potential distribution on lithium ion battery cathodes during battery operation. A sensing plate comprising a Si film grown epitaxially on a sapphire substrate was used as a terahertz emitter. The amplitude of terahertz radiation from the sensing plate could be related to the electric potential at the exact point where a femtosecond laser illuminated. Here, the sensing plate was integrated into a conventional can-type lithium ion battery and terahertz radiation from the sensing plate was observed during battery operation between 2.7 and 4.2 V. By scanning the laser, the distribution of terahertz amplitude radiated from the sensing plate was observed, which could be related to the electric potential distribution on the electrodes of the batteries. Localized electric potential could be visualized as the amplitude of terahertz radiation generated in the sensing plate, which was integrated beneath the battery electrode.

Imaging of Chemical Reactions Using a Terahertz Chemical Microscope

This study develops a terahertz (THz) chemical microscope (TCM) that visualizes the distribution of chemical reaction on a silicon-based sensing chip. This chip, called the sensing plate, was fabricated by depositing Si thin films on a sapphire substrate and thermally oxidizing the Si film surface. The Si thin film of the sensing plate was irradiated from the substrate side by a femtosecond laser, generating THz pulses that were radiated into free space through the surface field effect of the Si thin film. The surface field responds to chemical reactions on the surface of the sensing plate, changing the amplitude of the THz pulses. This paper first demonstrates the principle and experimental setup of the TCM and performs the imaging and measurement of chemical reactions, including the reactions of bio-related materials.

Label-free detection of low-molecular-weight samples using a terahertz chemical microscope

A terahertz chemical microscope (TCM) has been proposed and developed to visualize the distribution of biomolecular interactions on a sensing plate without any labels. In this study, the concanavalin A (Con A)–d-(+)-mannose (mannose) interaction was detected using the TCM with mannose applied as the analyte and Con A immobilized on the sensing plate. To demonstrate this interaction, the amplitude of terahertz pulses as a function of Con A–mannose interaction time, as well as the Con A–mannose coupling concentration, was evaluated. The results suggest that coupling kinetics may be evaluated using a TCM.

Ultra high throughput selection of enzyme by terahertz chemical microscope

Event Abstract Back to Event No Records Found Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Google Google Scholar PubMed Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Development of Terahertz Chemical Microscope for Industrial Applications

Development of Terahertz Chemical Microscope for Industrial Applications

Label free immune assay using terahertz chemical microscope

A terahertz chemical microscope (TCM) has been proposed and developed to visualize the distribution of the antibody–antigen bindings on the silicon based sensing plate without any labels and/or markers on the antibody. The sensing plate can emit the terahertz pulses by femtosecond laser pulses and the amplitude of the terahertz pulses can be related to the chemical or electric potential of the sensing plate surface at where the laser pulses are irradiated. Thus the potential distribution can be visualized as the map of the terahertz pulses amplitude.As the first demonstration of the label free immune assay, the mouse immunoglobulin G (IgG) was immobilized on the half part of the sensing plate and the mouse anti-IgG was combined with the IgG. The terahertz pulses were enhanced at where anti-IgG was combined with IgG on the sensing plate and the distributions of the IgG and anti-IgG bindings on the sensing plate were clearly seen as the TCM images. The amplitude of terahertz pulses as a function of the concentration of anti-IgG was also investigated.

Biosensing by a terahertz chemical microscope

Biosensing by a terahertz chemical microscope

Terahertz chemical microscope for label-free detection of protein complex

A terahertz (THz) chemical microscope (TCM) has been proposed and developed for label-free analysis of the interactions of proteins, including immune reactions. A SiO2/Si/sapphire plate was fabricated and emitted THz pulses from the sapphire side using a femtosecond laser. The amplitude of a THz pulse depends on the chemical potential of the SiO2 surface. As an initial demonstration, a biotin–avidin complex was analyzed using TCM. Results indicate that biotin concentrations of up to 10−12 mol/l could be detected, suggesting that a high sensitivity immunoassay system can be realized using this method. The distribution of the THz peak amplitude was measured, reflecting the distribution of the biotin–avidin complex on the plate.