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1.
Methods Mol Biol ; 2644: 133-154, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37142920

RESUMO

Microelectrode array (MEA) technology is a neurophysiological method that allows for the measurement of spontaneous or evoked neural activity to determine chemical effects thereon. Following assessment of compound effects on multiple endpoints that evaluate network function, a cell viability endpoint in the same well is determined using a multiplexed approach. Recently, it has become possible to measure electrical impedance of cells attached to the electrodes, where greater impedance indicates greater number of cells attached. This would allow rapid and repeated assessments of cell health as the neural network develops in longer exposure assays without impacting cell health. Typically, the lactate dehydrogenase (LDH) assay for cytotoxity and CellTiter-Blue® (CTB) assay for cell viability are only performed at the end of the chemical exposure period because these assays involve lysing of the cells. Procedures describing the multiplexed methods in acute and network formation screening are included in this chapter.


Assuntos
L-Lactato Desidrogenase , Neurônios , Microeletrodos , Sobrevivência Celular , Rede Nervosa
2.
J Neural Eng ; 20(3)2023 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-37141883

RESUMO

Objective.Carbon fiber (CF) is good for chronic neural recording due to the small diameter (7µm), high Young's modulus, and low electrical resistance, but most high-density carbon fiber (HDCF) arrays are manually assembled with labor-intensive procedures and limited by the accuracy and repeatability of the operator handling. A machine to automate the assembly is desired.Approach.The HDCF array assembly machine contains: (1) a roller-based CF extruder, (2) a motion system with three linear and one rotary stages, (3) an imaging system with two digital microscope cameras, and (4) a laser cutter. The roller-based extruder automatically feeds single CF as raw material. The motion system aligns the CF with the array backend then places it. The imaging system observes the relative position between the CF and the backend. The laser cutter cuts off the CF. Two image processing algorithms are implemented to align the CF with the support shanks and circuit connection pads.Main results.The machine was capable of precisely handling 6.8µm carbon fiber electrodes (CFEs). Each electrode was placed into a 12µm wide trenches in a silicon support shank. Two HDCF arrays with 16 CFEs populated on 3 mm shanks (with 80µm pitch) were fully assembled. Impedance measurements were found to be in good agreement with manual assembled arrays. One HDCF array was implanted in the motor cortex in an anesthetized rat and was able to detect single unit activity.Significance.This machine can eliminate the manual labor-intensive handling, alignment and placement of single CF during assembly, providing a proof-of-concepts towards fully automated HDCF array assembly and batch production.


Assuntos
Fenômenos Eletrofisiológicos , Ratos , Animais , Fibra de Carbono , Microeletrodos , Eletrodos Implantados , Impedância Elétrica
3.
Cells ; 12(9)2023 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-37174670

RESUMO

The currently accepted methods for neurotoxicity (NT) testing rely on animal studies. However, high costs and low testing throughput hinder their application for large numbers of chemicals. To overcome these limitations, in vitro methods are currently being developed based on human-induced pluripotent stem cells (hiPSC) that allow higher testing throughput at lower costs. We applied six different protocols to generate 3D BrainSphere models for acute NT evaluation. These include three different media for 2D neural induction and two media for subsequent 3D differentiation resulting in self-organized, organotypic neuron/astrocyte microtissues. All induction protocols yielded nearly 100% NESTIN-positive hiPSC-derived neural progenitor cells (hiNPCs), though with different gene expression profiles concerning regional patterning. Moreover, gene expression and immunocytochemistry analyses revealed that the choice of media determines neural differentiation patterns. On the functional level, BrainSpheres exhibited different levels of electrical activity on microelectrode arrays (MEA). Spike sorting allowed BrainSphere functional characterization with the mixed cultures consisting of GABAergic, glutamatergic, dopaminergic, serotonergic, and cholinergic neurons. A test method for acute NT testing, the human multi-neurotransmitter receptor (hMNR) assay, was proposed to apply such MEA-based spike sorting. These models are promising tools not only in toxicology but also for drug development and disease modeling.


Assuntos
Células-Tronco Neurais , Neurônios , Animais , Humanos , Células Cultivadas , Microeletrodos , Neurônios/metabolismo , Células-Tronco Neurais/metabolismo , Diferenciação Celular
4.
ACS Appl Mater Interfaces ; 15(19): 22854-22863, 2023 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-37141163

RESUMO

Biocompatible and plastic neural interface devices allow for minimally invasive recording of brain activity. Increasing electrode density in such devices is essential for high-resolution neural recordings. Superimposing conductive leads in devices can help multiply the number of recording sites while keeping probes width small and suitable for implantation. However, because of leads' vertical proximity, this can create capacitive coupling (CC) between overlapping channels, which leads to crosstalk. Here, we present a thorough investigation of CC phenomenon in multi-gold layer thin-film multi-electrode arrays with a parylene C (PaC) insulation layer between superimposed leads. We also propose a guideline on the design, fabrication, and characterization of such type of neural interface devices for high spatial resolution recording. Our results demonstrate that the capacitance created through CC between superimposed tracks decreases non-linearly and then linearly with the increase of insulation thickness. We identify an optimal PaC insulation thickness that leads to a drastic reduction of CC between superimposed gold channels while not significantly increasing the overall device thickness. Finally, we show that double gold layer electrocorticography probes with the optimal insulation thickness exhibit similar performances in vivo when compared to single-layer devices. This confirms that these probes are adequate for high-quality neural recordings.


Assuntos
Eletrocorticografia , Ouro , Eletrodos , Condutividade Elétrica , Capacitância Elétrica , Eletrodos Implantados , Microeletrodos
6.
Sci Rep ; 13(1): 8062, 2023 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-37202451

RESUMO

Continuous monitoring of tissue microphysiology is a key enabling feature of the organ-on-chip (OoC) approach for in vitro drug screening and disease modeling. Integrated sensing units are particularly convenient for microenvironmental monitoring. However, sensitive in vitro and real-time measurements are challenging due to the inherently small size of OoC devices, the characteristics of commonly used materials, and external hardware setups required to support the sensing units. Here we propose a silicon-polymer hybrid OoC device that encompasses transparency and biocompatibility of polymers at the sensing area, and has the inherently superior electrical characteristics and ability to house active electronics of silicon. This multi-modal device includes two sensing units. The first unit consists of a floating-gate field-effect transistor (FG-FET), which is used to monitor changes in pH in the sensing area. The threshold voltage of the FG-FET is regulated by a capacitively-coupled gate and by the changes in charge concentration in close proximity to the extension of the floating gate, which functions as the sensing electrode. The second unit uses the extension of the FG as microelectrode, in order to monitor the action potential of electrically active cells. The layout of the chip and its packaging are compatible with multi-electrode array measurement setups, which are commonly used in electrophysiology labs. The multi-functional sensing is demonstrated by monitoring the growth of induced pluripotent stem cell-derived cortical neurons. Our multi-modal sensor is a milestone in combined monitoring of different, physiologically-relevant parameters on the same device for future OoC platforms.


Assuntos
Silício , Transistores Eletrônicos , Microeletrodos , Eletrônica , Sistemas Microfisiológicos
7.
Sensors (Basel) ; 23(7)2023 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-37050519

RESUMO

Previous studies have demonstrated the electropermeabilization of cell membranes exposed to an electric field with moderate intensity (<2 V/cm) and a frequency of <100 MHz. Bioimpedance spectroscopy (BIS) is an electrical characterization technique that can be useful in studying this phenomenon because it is already used for electroporation. In this paper, we report a device designed to perform BIS on single cells and expose them to an electric field simultaneously. It also allows cells to be monitored by visualization through a transparent exposure electrode. This device is based on a lab-on-a-chip (LOC) with a microfluidic cell-trapping system and microelectrodes for BIS characterization. We present numerical simulations that support the design of the LOC. We also describe the fabrication of the LOC and the first electrical characterization of its measurement bandwidth. This first test, performed on reference medium with a conductivity in the same order than human cells, confirms that the measurement capabilities of our device are suitable for electrical cells characterization.


Assuntos
Eletricidade , Microfluídica , Humanos , Condutividade Elétrica , Microfluídica/métodos , Microeletrodos , Análise Espectral , Impedância Elétrica
8.
ACS Sens ; 8(4): 1810-1818, 2023 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-37014663

RESUMO

Precise and directional couplings of functional nanomaterials with implantable microelectrode arrays (IMEAs) are critical for the manufacture of sensitive enzyme-based electrochemical neural sensors. However, there is a gap between the microscale of IMEA and conventional bioconjugation techniques for enzyme immobilization, which leads to a series of challenges such as limited sensitivity, signal crosstalk, and high detection voltage. Here, we developed a novel method using carboxylated graphene oxide (cGO) to directionally couple the glutamate oxidase (GluOx) biomolecules onto the neural microelectrode to monitor glutamate concentration and electrophysiology in the cortex and hippocampus of epileptic rats under RuBi-GABA modulation. The resulting glutamate IMEA exhibited good performance involving less signal crosstalk between microelectrodes, lower reaction potential (0.1 V), and higher linear sensitivity (141.00 ± 5.66 nA µM-1 mm-2). The excellent linearity ranged from 0.3 to 68 µM (R = 0.992), and the limit of detection was 0.3 µM. For epileptic rats, the proposed IMEA sensitively obtained synergetic variations in the action potential (Spike), local field potentials (LFPs), and glutamate of the cortex and hippocampus during seizure and RuBi-GABA inhibition. We found that the increase in glutamate preceded the burst of electrophysiological signals. At the same time, both changes in the hippocampus preceded the cortex. This reminded us that glutamate changes in the hippocampus could serve as important indicators for early warning of epilepsy. Our findings provided a new technical strategy for directionally stabilizing enzymes onto the IMEA with versatile implications for various biomolecules' modification and facilitated the development of detecting tools for understanding the neural mechanism.


Assuntos
Epilepsia , Hipocampo , Ratos , Animais , Microeletrodos , Ratos Sprague-Dawley , Hipocampo/fisiologia , Ácido Glutâmico , Ácido gama-Aminobutírico/farmacologia
9.
Anal Chem ; 95(17): 6828-6835, 2023 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-37071798

RESUMO

Aptamers have been employed as the biorecognition element in electrochemical aptamer-based (E-AB) biosensors, for the detection of a diverse range of analyte molecules, on electrodes with sizescales ranging from a few microns to several millimeters. Simultaneous detection of multiple different analytes requires the selective modification of multiple electrode surfaces with different aptamers. This process is typically achieved by incubating separate macroscale electrodes in a solution with the desired aptamer, which is unsuitable for microelectrode arrays in which the electrodes are closely spaced. In this work, we selectively modified electrode surfaces with thiolated aptamers of different single-stranded DNA sequences, by successive removal and addition of thiol monolayers. This was achieved by electrodesorption of thiol monolayers using controlled potential, to expose unmodified gold electrodes to be modified with a different thiolated aptamer, thus enabling multiple different aptamers to be used on the surfaces of closely spaced microelectrodes. All aptamers were methylene blue terminated, allowing redox currents to be measured and used to monitor aptamer probe packing density on the electrode surface and the selectivity of the sensors. Here, we demonstrate the microscale E-AB sensor multianalyte detection method using aptamers for target analytes, adenosine triphosphate, dopamine, and serotonin, which can ultimately be applied to perform localized simultaneous detection using electrode arrays.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Microeletrodos , Aptâmeros de Nucleotídeos/química , Eletrodos , Oxirredução , Técnicas Biossensoriais/métodos , DNA de Cadeia Simples , Ouro/química , Técnicas Eletroquímicas/métodos
10.
Sci Rep ; 13(1): 6973, 2023 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-37117214

RESUMO

Shape-morphable electrode arrays can form 3D surfaces to conform to complex neural anatomy and provide consistent positioning needed for next-generation neural interfaces. Retinal prostheses need a curved interface to match the spherical eye and a coverage of several cm to restore peripheral vision. We fabricated a full-field array that can (1) cover a visual field of 57° based on electrode position and of 113° based on the substrate size; (2) fold to form a compact shape for implantation; (3) self-deploy into a curvature fitting the eye after implantation. The full-field array consists of multiple polymer layers, specifically, a sandwich structure of elastomer/polyimide-based-electrode/elastomer, coated on one side with hydrogel. Electrodeposition of high-surface-area platinum/iridium alloy significantly improved the electrical properties of the electrodes. Hydrogel over-coating reduced electrode performance, but the electrodes retained better properties than those without platinum/iridium. The full-field array was rolled into a compact shape and, once implanted into ex vivo pig eyes, restored to a 3D curved surface. The full-field retinal array provides significant coverage of the retina while allowing surgical implantation through an incision 33% of the final device diameter. The shape-changing material platform can be used with other neural interfaces that require conformability to complex neuroanatomy.


Assuntos
Irídio , Platina , Animais , Suínos , Eletrodos Implantados , Irídio/química , Polímeros , Hidrogéis , Retina/cirurgia , Elastômeros , Microeletrodos
11.
Nano Lett ; 23(8): 3217-3223, 2023 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-37019439

RESUMO

Bioelectrical variations trigger different cell responses, including migration, mitosis, and mutation. At the tissue level, these actions result in phenomena such as wound healing, proliferation, and pathogenesis. Monitoring these mechanisms dynamically is highly desirable in diagnostics and drug testing. However, existing technologies are invasive: either they require physical access to the intracellular compartments, or they imply direct contact with the cellular medium. Here, we present a novel approach for the passive recording of electrical signals from non-excitable cells adhering to 3D microelectrodes, based on optical mirroring. Preliminary results yielded a fluorescence intensity output increase of the 5,8% in the presence of a HEK-293 cell on the electrode compared to bare microelectrodes. At present, this technology may be employed to evaluate cell-substrate adhesion and monitor cell proliferation. Further refinements could allow extrapolating quantitative data on surface charges and resting potential to investigate the electrical phenomena involved in cell migration and cancer progression.


Assuntos
Neoplasias , Humanos , Células HEK293 , Neoplasias/patologia , Potenciais da Membrana , Adesão Celular , Microeletrodos
12.
J Neural Eng ; 20(3)2023 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-37105161

RESUMO

Objective.Neuropixels (NP) probes are a significant advance in electrophysiological recording technology that enable monitoring of hundreds of neurons in the brain simultaneously at different depths. Application of this technology has been predominately in rodents, however widespread use in non-human primates (NHPs) such as rhesus macaques has been limited. In this study we sought to overcome two overarching challenges that impede acute NP implantation in NHPs: (1) traditional microdrive systems that mount to cephalic chambers are commonly used to access cortical areas for microelectrode recordings but are not designed to accommodate NP probes, and (2) NHPs have thick dura mater and tissue growth within the cephalic chambers which poses a challenge for insertion of the extremely fragile NP probe.Approach.In this study we present a novel NP guide tube system that can be adapted to commercial microdrive systems and demonstrate an implant method using the NP guide tube system. This system was developed using a combination of CAD design, 3D printing, and small part machining. Software programs, 3D Slicer and SolidWorks were used to target cortical areas, approximate recording depths and locations, and for in-silico implant testing.Main results.We performedin vivotesting to validate our methodology, successfully implanting, explanting, and reimplanting NP probes. We collected stable neurophysiological recordings in the premotor cortex of a rhesus macaque at rest and during performance of a reaching task.Significance.In this study we demonstrate a robust Neuropixels implant system that allows multiple penetrations with the same NP probe and share design files that will facilitate the adoption of this powerful recording technology for NHP studies.


Assuntos
Encéfalo , Neurônios , Animais , Macaca mulatta , Encéfalo/fisiologia , Microeletrodos , Neurônios/fisiologia , Eletrodos Implantados , Impressão Tridimensional
13.
IEEE Trans Biomed Circuits Syst ; 17(2): 202-228, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-37028090

RESUMO

Rapid, high-sensitivity, and real-time characterization of microorganisms plays a significant role in several areas, including clinical diagnosis, human healthcare, early detection of outbreaks, and the protection of living beings. Integrating microbiology and electrical engineering promises the development of low-cost, miniaturized, autonomous, and high-sensitivity sensors to quantify and characterize bacterial strains at various concentrations. Electrochemical-based biosensors are receiving particular attention in microbiological applications among the different biosensing devices. Several approaches have been adopted to design and fabricate cutting-edge, miniaturized, and portable electrochemical biosensors to track and monitor bacterial cultures in real time. These techniques differ in their sensing interface circuits and microelectrode fabrication. The goals of this review are (1) to summarize the current state of CMOS sensing circuit designs in label-free electrochemical biosensors for bacteria monitoring and (2) to discuss the material and size of the electrodes used in electrochemical biosensors in microbiological applications. In this paper, we reviewed the latest and most advanced CMOS integrated interface circuits that have recently been used in electrochemical biosensors to identify and characterize bacteria species, such as impedance spectroscopy, capacitive, amperometry, and voltammetry, etc. In addition to the interface circuit design, other crucial factors, such as the material and scale of the electrodes, must be considered to increase the sensitivity of electrochemical biosensors. Surveying the literature in this field improves our knowledge about the impact of electrode designs and materials on sensing precision and will help future designers adapt, design, and fabricate appropriate electrode configurations based on their application. Thus, we summarized the conventional microelectrode designs and materials mainly employed in microbial sensors, including interdigitated electrodes (IDEs), microelectrode arrays (MEAs), paper, and carbon-based electrodes, etc.


Assuntos
Bactérias , Técnicas Biossensoriais , Humanos , Microeletrodos , Espectroscopia Dielétrica , Técnicas Eletroquímicas
14.
Biomaterials ; 297: 122102, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37015177

RESUMO

Invasive neuroprosthetics rely on microelectrodes (MEs) to record or stimulate the activity of large neuron assemblies. However, MEs are subjected to tissue reactivity in the central nervous system (CNS) due to the foreign body response (FBR) that contribute to chronic neuroinflammation and ultimately result in ME failure. An endogenous, acute set of mechanisms responsible for the recognition and targeting of foreign objects, called the innate immune response, immediately follows the ME implant-induced trauma. Inflammasomes are multiprotein structures that play a critical role in the initiation of an innate immune response following CNS injuries. The activation of inflammasomes facilitates a range of innate immune response cascades and results in neuroinflammation and programmed cell death. Despite our current understanding of inflammasomes, their roles in the context of neural device implantation remain unknown. In this study, we implanted a non-functional Utah electrode array (UEA) into the rat somatosensory cortex and studied the inflammasome signaling and the corresponding downstream effects on inflammatory cytokine expression and the inflammasome-mediated cell death mechanism of pyroptosis. Our results not only demonstrate the continuous activation of inflammasomes and their contribution to neuroinflammation at the electrode-tissue interface but also reveal the therapeutic potential of targeting inflammasomes to attenuate the FBR in invasive neuroprosthetics.


Assuntos
Corpos Estranhos , Inflamassomos , Ratos , Animais , Inflamassomos/metabolismo , Inflamação/metabolismo , Doenças Neuroinflamatórias , Microeletrodos , Imunidade Inata
15.
ACS Appl Bio Mater ; 6(5): 1701-1719, 2023 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-37076978

RESUMO

Transparent microelectrodes have emerged as promising tools to combine electrical and optical sensing and modulation modalities in many areas of biological and biomedical research. Compared to conventional opaque microelectrodes, they offer a number of specific advantages that can enable advances in functionality and performance. In addition to optical transparency, the mechanical softness feature is desired to minimize foreign body responses, increase biocompatibility, and avoid loss of functionality. In this review, we present recent research from the past several years on transparent microelectrode-based soft bioelectronic devices with an emphasis on their material properties and advanced device designs, as well as multimodal application scenarios for neuroscience and cardiology. First, we introduce material candidates with proper electrical, optical, and mechanical properties for soft transparent microelectrodes. We then discuss examples of soft transparent microelectrode arrays tailored to combine electrical recording and/or stimulation with optical imaging and/or optogenetic modulation of the brain and the heart. Next, we summarize the most recent progress on soft opto-electric devices integrating transparent microelectrodes with microscale light-emitting diodes and/or photodetectors into single and hybrid microsystems as powerful tools to explore the brain and heart functions. A brief overview of possible future directions of soft transparent microelectrode-based biointerfaces is provided to conclude the review.


Assuntos
Pesquisa Biomédica , Encéfalo , Microeletrodos , Eletrodos Implantados , Eletricidade
16.
J Cardiovasc Electrophysiol ; 34(5): 1216-1227, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37087672

RESUMO

INTRODUCTION: The assessment of the ventricular myocardial substrate critically depends on the size of mapping electrodes, their orientation with respect to wavefront propagation, and interelectrode distance. We conducted a dual-center study to evaluate the impact of microelectrode mapping in patients undergoing catheter ablation (CA) of ventricular tachycardia (VT). METHODS: We included 21 consecutive patients (median age, 68 [12], 95% male) with structural heart disease undergoing CA for electrical storm (n = 14) or recurrent VT (n = 7) using the QDOT Micro catheter and a multipolar catheter (PentaRay, n = 9). The associations of peak-to-peak maximum standard bipolar (BVc ) and minibipolar (PentaRay, BVp ) with microbipolar (BVµMax ) voltages were respectively tested in sinus rhythm with mixed effect models. Furthermore, we compared the features of standard bipolar (BE) and microbipolar (µBE) electrograms in sinus rhythm at sites of termination with radiofrequency energy. RESULTS: BVµMax was moderately associated with both BVc (ß = .85, p < .01) and BVp (ß = .56, p < .01). BVµMax was 0.98 (95% CI: 0.93-1.04, p < .01) mV larger than corresponding BVc , and 0.27 (95% CI: 0.16-0.37, p < .01) mV larger than matching BVp in sinus rhythm, with higher percentage differences in low voltage regions, leading to smaller endocardial dense scar (2.3 [2.7] vs. 12.1 [17] cm2 , p < .01) and border zone (3.2 [7.4] vs. 4.8 [20.1] cm2 , p = .03) regions in microbipolar maps compared to standard bipolar maps. Late potentials areas were nonsignificantly greater in microelectrode maps, compared to standard electrode maps. At sites of VT termination (n = 14), µBE were of higher amplitude (0.9 [0.8] vs. 0.4 [0.2] mV, p < .01), longer duration (117 [66] vs. 74 [38] ms, p < .01), and with greater number of peaks (4 [2] vs. 2 [1], p < .01) in sinus rhythm compared to BE. CONCLUSION: microelectrode mapping is more sensitive than standard bipolar mapping in the identification of viable myocytes in SR, and may facilitate recognition of targets for CA.


Assuntos
Ablação por Cateter , Taquicardia Ventricular , Humanos , Masculino , Idoso , Feminino , Microeletrodos , Resultado do Tratamento , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/cirurgia , Taquicardia Ventricular/complicações , Arritmias Cardíacas/cirurgia , Ablação por Cateter/efeitos adversos , Ablação por Cateter/métodos , Cicatriz
17.
Anal Chim Acta ; 1258: 341169, 2023 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-37087292

RESUMO

3D-printing has shown an outstanding performance for the production of versatile electrochemical devices. However, there is a lack of studies in the field of 3D-printed miniaturized settings for multiplex biosensing. In this work, we propose a fully 3D-printed micro-volume cell containing six working electrodes (WEs) that operates with 250 µL of sample. A polylactic acid/carbon black conductive filament (PLA/CB) was used to print the WEs and subsequently modified with graphene oxide (GO), to support protein binding. Cyclic voltammetry was employed to investigate the electrochemical behaviour of the novel multi-electrode cell. In the presence of K3[Fe(CN)6], PLA/CB/GO showed adequate peak resolution for subsequent label-free immunosensing. The innovative 3D-printed cell was applied for multiplex voltammetric detection of three COVID-19 biomarkers as a proof-of-concept. The multiple sensors showed a wide linear range with detection limits of 5, 1 and 1 pg mL-1 for N-protein, SRBD-protein, and anti-SRBD, respectively. The sensor performance enabled the selective sequential detection of N protein, SRBD protein, and anti-SRBD at biological levels in saliva and serum. In summary, the miniaturized six-electrode cell presents an alternative for the low-cost and fast production of customizable devices for multi-target sensing with promising application in the development of point-of-care sensors.


Assuntos
COVID-19 , Humanos , COVID-19/diagnóstico , Eletrodos , Microeletrodos , Poliésteres , Impressão Tridimensional , Biomarcadores
18.
Anal Chem ; 95(17): 6791-6800, 2023 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-37088902

RESUMO

The selective and sensitive sensing of neurochemicals is essential to decipher in-brain chemistry underlying brain pathophysiology. The recent development of flexible and multifunctional polymer-based fibers has been shown useful in recording and modulating neural activities, primarily electrical ones. In this study, we were able to realize fiber-based neurochemical sensing with high sensitivity and selectivity. We achieved a generalizable method to couple aptamers, a type of synthetic receptors on the carbon composites within fibers, as microsensors for highly selective neurochemical detection. Such an aptamer-coupled microelectrode fiber sensor (apta-µFS) enables simple, label-free, and sensitive dopamine (DA) detection down to 5 nM with ultrahigh specificity across major interferents. We succeeded in monitoring DA selectively within the living brain using our apta-µFS. We further showed the proof-of-concept of using microelectronic fiber-based toolsets to target neural pathways across electrical and chemical modalities. In summary, such fiber-based toolsets hold great potential to advance multimodal mechanistic understanding of brain pathophysiology.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Microeletrodos , Técnicas Biossensoriais/métodos , Encéfalo/metabolismo , Aptâmeros de Nucleotídeos/metabolismo , Polímeros/metabolismo , Dopamina/metabolismo
19.
Biosens Bioelectron ; 229: 115227, 2023 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-36940662

RESUMO

Currently, only a few small devices are capable of continuously recording the physiological states of neurons in real time. Micro-electrode arrays (MEAs) are widely used as electrophysiological technology to detect the excitability of neurons non-invasively. However, the development of miniaturized and multi-parameter MEAs capable of real-time recording remains challenging. In this study, an on-chip micro-electrode and platinum resistor array (MEPRA) biosensor was designed and fabricated to monitor both the electrical and temperature signals of cells synchronously in real time. Such on-chip sensor maintains high sensitivity and stability. The MEPRA biosensor was further used to investigate the effects of propionic acid (PA) on primary neurons. The results demonstrate that PA affects the temperature and firing frequency of primary cortical neurons in concentration-dependent manners. The changes of temperature and firing frequency work in tandem with neuronal physiological status, including neuron viability, intracellular calcium concentration, neural plasticity, and mitochondrial function. This highly biocompatible, stable, and sensitive MEPRA biosensor may provide high-precision reference information for investigating the physiological responses of neuron cells under various conditions.


Assuntos
Técnicas Biossensoriais , Técnicas Biossensoriais/métodos , Eletrodos , Neurônios/fisiologia , Microeletrodos
20.
Lab Chip ; 23(9): 2193-2205, 2023 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-36891773

RESUMO

Perforated microelectrode arrays (pMEAs) have become essential tools for ex vivo retinal electrophysiological studies. pMEAs increase the nutrient supply to the explant and alleviate the accentuated curvature of the retina, allowing for long-term culture and intimate contacts between the retina and electrodes for electrophysiological measurements. However, commercial pMEAs are not compatible with in situ high-resolution optical imaging and lack the capability of controlling the local microenvironment, which are highly desirable features for relating function to anatomy and probing physiological and pathological mechanisms in retina. Here we report on microfluidic pMEAs (µpMEAs) that combine transparent graphene electrodes and the capability of locally delivering chemical stimulation. We demonstrate the potential of µpMEAs by measuring the electrical response of ganglion cells to locally delivered high K+ stimulation under controlled microenvironments. Importantly, the capability for high-resolution confocal imaging of the retina tissue on top of the graphene electrodes allows for further analyses of the electrical signal source. The new capabilities provided by µpMEAs could allow for retinal electrophysiology assays to address key questions in retinal circuitry studies.


Assuntos
Grafite , Microeletrodos , Microfluídica , Retina/fisiologia , Neurônios/fisiologia , Estimulação Elétrica
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