Miniature multiplexed label-free pH probe in vivo

Guo, Yuanyuan; Werner, Carl Frederik; Handa, Shoma; Wang, Mengyun; Ohshiro, Tomokazu; Mushiake, Hajime; Yoshinobu, Tatsuo

doi:10.1016/j.bios.2020.112870

Cited by 25 publications

(31 citation statements)

References 33 publications

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“…Among explored functionalities, electrochemical sensing, which offers robustness and simplicity in detection across various compounds [ 8 ], still remains poorly investigated in fibers. Though recent efforts to develop fiber-type in vivo biochemical sensors have brought successful results [ 9 , 10 ], the integrated electrochemical modalities are still not yet fully demonstrated, due to the lack of electrode materials which can satisfy both electrochemical sensing performance as well as thermomechanical restrictions imposed by the thermal drawing process. In recent studies, carbon-based polymer composites have been successfully integrated in the fibers [ 11 ], mainly for their enhanced electrical properties.…”

Section: Introductionmentioning

confidence: 99%

Thermally Drawn CNT-Based Hybrid Nanocomposite Fiber for Electrochemical Sensing

Nishimoto

Sato

et al. 2022

Biosensors

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Nowadays, bioelectronic devices are evolving from rigid to flexible materials and substrates, among which thermally-drawn-fiber-based bioelectronics represent promising technologies thanks to their inherent flexibility and seamless integration of multi-functionalities. However, electrochemical sensing within fibers remains a poorly explored area, as it imposes new demands for material properties—both the electrochemical sensitivity and the thermomechanical compatibility with the fiber drawing process. Here, we designed and fabricated microelectrode fibers made of carbon nanotube (CNT)-based hybrid nanocomposites and further evaluated their detailed electrochemical sensing performances. Carbon-black-impregnated polyethylene (CB-CPE) was chosen as the base material, into which CNT was loaded homogeneously in a concentration range of 3.8 to 10 wt%. First, electrical impedance characterization of CNT nanocomposites showed a remarkable decrease of the resistance with the increase in CNT loading ratio, suggesting that CNTs notably increased the effective electrical current pathways inside the composites. In addition, the proof-of-principle performance of fiber-based microelectrodes was characterized for the detection of ferrocenemethanol (FcMeOH) and dopamine (DA), exhibiting an ultra-high sensitivity. Additionally, we further examined the long-term stability of such composite-based electrode in exposure to the aqueous environment, mimicking the in vivo or in vitro settings. Later, we functionalized the surface of the microelectrode fiber with ion-sensitive membranes (ISM) for the selective sensing of Na+ ions. The miniature fiber-based electrochemical sensor developed here holds great potential for standalone point-of-care sensing applications. In the future, taking full advantage of the thermal drawing process, the electrical, optical, chemical, and electrochemical modalities can be all integrated together within a thin strand of fiber. This single fiber can be useful for fundamental multi-mechanistic studies for biological applications and the weaved fibers can be further applied for daily health monitoring as functional textiles.

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Section: Introductionmentioning

confidence: 99%

Thermally Drawn CNT-Based Hybrid Nanocomposite Fiber for Electrochemical Sensing

Nishimoto

Sato

et al. 2022

Biosensors

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“…Two-dimensional ion imaging provides visualization and dynamic analysis of processes such as electrolysis and corrosion [3]. It is also possible to obtain the distribution of ion concentrations in the vicinity of cells and measure the metabolic activity of living cells [4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…An analog micromirror was adopted for the raster scan of the sensor substrate, which enables high-resolution pH imaging with a frame rate of 8 fps [18]. The pH changes in the hippocampal formation of rats were obtained using an all-in-one pH probe [8]. The flat-band voltage shift due to the ions of the semiconductor in an EIS structure was measured with light.…”

Section: Introductionmentioning

confidence: 99%

High Spatial Resolution Ion Imaging by Focused Electron-Beam Excitation with Nanometric Thin Sensor Substrate

Nii

Inami

Kawata

2022

Sensors

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We developed a high spatially-resolved ion-imaging system using focused electron beam excitation. In this system, we designed a nanometric thin sensor substrate to improve spatial resolution. The principle of pH measurement is similar to that of a light-addressable potentiometric sensor (LAPS), however, here the focused electron beam is used as an excitation carrier instead of light. A Nernstian-like pH response with a pH sensitivity of 53.83 mV/pH and linearity of 96.15% was obtained. The spatial resolution of the imaging system was evaluated by applying a photoresist to the sensing surface of the ion-sensor substrate. A spatial resolution of 216 nm was obtained. We achieved a substantially higher spatial resolution than that reported in the LAPS systems.

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“…A device simulation of a LAPS revealed that this effect reduces the thickness of the depletion layer and lowers the spatial resolution of chemical imaging by a LAPS [14]. Finally, when a LAPS is applied to an in vivo measurement (for example, in the brain of an animal [15]), the injection of energy in any form into the body must be minimized as a safety measure, as well as to avoid its potential influence on the living organism.…”

Section: Introductionmentioning

confidence: 99%

Efficient Illumination for a Light-Addressable Potentiometric Sensor

Yoshinobu

Miyamoto

2022

Sensors

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A light-addressable potentiometric sensor (LAPS) is a chemical sensor that is based on the field effect in an electrolyte–insulator–semiconductor structure. It requires modulated illumination for generating an AC photocurrent signal that responds to the activity of target ions on the sensor surface. Although high-power illumination generates a large signal, which is advantageous in terms of the signal-to-noise ratio, excess light power can also be harmful to the sample and the measurement. In this study, we tested different waveforms of modulated illuminations to find an efficient illumination for a LAPS that can enlarge the signal as much as possible for the same input light power. The results showed that a square wave with a low duty ratio was more efficient than a sine wave by a factor of about two.

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Miniature multiplexed label-free pH probe in vivo

Cited by 25 publications

References 33 publications

Thermally Drawn CNT-Based Hybrid Nanocomposite Fiber for Electrochemical Sensing

Thermally Drawn CNT-Based Hybrid Nanocomposite Fiber for Electrochemical Sensing

High Spatial Resolution Ion Imaging by Focused Electron-Beam Excitation with Nanometric Thin Sensor Substrate

Efficient Illumination for a Light-Addressable Potentiometric Sensor

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