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Ji T, Ye W, Xiao W, Dawson G, Dong Q, Gwenin C. Iridium oxide-modified reference screen-printed electrodes for point-of-care portable electrochemical cortisol detection. Talanta 2024; 280:126776. [PMID: 39216420 DOI: 10.1016/j.talanta.2024.126776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 07/10/2024] [Accepted: 08/24/2024] [Indexed: 09/04/2024]
Abstract
Cortisol is a well-known stress biomarker; this study focuses on using electrochemical immuno-sensing to measure the concentration of cortisol selectively and sensitively in artificial samples. Anti-cortisol antibodies have been immobilised on polycrystalline Au electrodes via strong covalent thiol bonds, fabricating an electrochemical bio-immunosensor for cortisol detection. IrOx was then anodically electrodeposited as a reference electrode on a commercial screen-printed electrode and electrochemical impedance spectrometry (EIS) studies were used to correlate the electrochemical response to cortisol concentration and the induced changes in charge transfer resistance (Rct). A linear relationship between the Rct and the logarithm of cortisol concentration was found in concentrations ranging from 1 ng/mL to 1 mg/mL with limit of detection at 11.85 pg/mL (32.69 pM). The modification of the reference electrode with iridium oxide has greatly improved the reproducibility of the screen-printed electrode. The sensing system can provide a reliable and sensitive detection approach for cortisol measurements.
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Affiliation(s)
- Tong Ji
- Xi'an Jiaotong-Liverpool University, School of Science, Department of Chemistry, No. 111 Ren'ai Road, Suzhou Industrial Park, Suzhou, People's Republic of China
| | - Wen Ye
- Xi'an Jiaotong-Liverpool University, School of Science, Department of Chemistry, No. 111 Ren'ai Road, Suzhou Industrial Park, Suzhou, People's Republic of China
| | - Weiyu Xiao
- Xi'an Jiaotong-Liverpool University, School of Science, Department of Chemistry, No. 111 Ren'ai Road, Suzhou Industrial Park, Suzhou, People's Republic of China
| | - Graham Dawson
- Xi'an Jiaotong-Liverpool University, School of Science, Department of Chemistry, No. 111 Ren'ai Road, Suzhou Industrial Park, Suzhou, People's Republic of China
| | - Qiuchen Dong
- Xi'an Jiaotong-Liverpool University, School of Science, Department of Chemistry, No. 111 Ren'ai Road, Suzhou Industrial Park, Suzhou, People's Republic of China.
| | - Christopher Gwenin
- School of Applied Sciences Division of Health Sciences, Abertay University, Bell St, Dundee, DD1 1HG, United Kingdom.
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2
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Robbins E, Wong B, Pwint MY, Salavatian S, Mahajan A, Cui XT. Improving Sensitivity and Longevity of In Vivo Glutamate Sensors with Electrodeposited NanoPt. ACS APPLIED MATERIALS & INTERFACES 2024; 16:40570-40580. [PMID: 39078097 PMCID: PMC11310907 DOI: 10.1021/acsami.4c06692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 07/24/2024] [Accepted: 07/24/2024] [Indexed: 07/31/2024]
Abstract
In vivo glutamate sensing has provided valuable insight into the physiology and pathology of the brain. Electrochemical glutamate biosensors, constructed by cross-linking glutamate oxidase onto an electrode and oxidizing H2O2 as a proxy for glutamate, are the gold standard for in vivo glutamate measurements for many applications. While glutamate sensors have been employed ubiquitously for acute measurements, there are almost no reports of long-term, chronic glutamate sensing in vivo, despite demonstrations of glutamate sensors lasting for weeks in vitro. To address this, we utilized a platinum electrode with nanometer-scale roughness (nanoPt) to improve the glutamate sensors' sensitivity and longevity. NanoPt improved the GLU sensitivity by 67.4% and the sensors were stable in vitro for 3 weeks. In vivo, nanoPt glutamate sensors had a measurable signal above a control electrode on the same array for 7 days. We demonstrate the utility of the nanoPt sensors by studying the effect of traumatic brain injury on glutamate in the rat striatum with a flexible electrode array and report measurements of glutamate taken during the injury itself. We also show the flexibility of the nanoPt platform to be applied to other oxidase enzyme-based biosensors by measuring γ-aminobutyric acid in the porcine spinal cord. NanoPt is a simple, effective way to build high sensitivity, robust biosensors harnessing enzymes to detect neurotransmitters in vivo.
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Affiliation(s)
- Elaine
M. Robbins
- Department
of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Benjamin Wong
- Department
of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- Department
of Anesthesiology & Perioperative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, United States
| | - May Yoon Pwint
- Department
of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- Center
for Neural Basis of Cognition, University
of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Siamak Salavatian
- Department
of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- Department
of Anesthesiology & Perioperative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, United States
| | - Aman Mahajan
- Department
of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- Department
of Anesthesiology & Perioperative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, United States
| | - Xinyan Tracy Cui
- Department
of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- Center
for Neural Basis of Cognition, University
of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- McGowan
Institute for Regenerative Medicine, University
of Pittsburgh, Pittsburgh, Pennsylvania 15261, United
States
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3
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Wu B, Castagnola E, McClung CA, Cui XT. PEDOT/CNT Flexible MEAs Reveal New Insights into the Clock Gene's Role in Dopamine Dynamics. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2308212. [PMID: 38430532 PMCID: PMC11251561 DOI: 10.1002/advs.202308212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/26/2024] [Indexed: 03/04/2024]
Abstract
Substantial evidence has shown that the Circadian Locomotor Output Cycles Kaput (Clock) gene is a core transcription factor of circadian rhythms that regulates dopamine (DA) synthesis. To shed light on the mechanism of this interaction, flexible multielectrode arrays (MEAs) are developed that can measure both DA concentrations and electrophysiology chronically. The dual functionality is enabled by conducting polymer PEDOT doped with acid-functionalized carbon nanotubes (CNT). The PEDOT/CNT microelectrode coating maintained stable electrochemical impedance and DA detection by square wave voltammetry for 4 weeks in vitro. When implanted in wild-type (WT) and Clock mutation (MU) mice, MEAs measured tonic DA concentration and extracellular neural activity with high spatial and temporal resolution for 4 weeks. A diurnal change of DA concentration in WT is observed, but not in MU, and a higher basal DA concentration and stronger cocaine-induced DA increase in MU. Meanwhile, striatal neuronal firing rate is found to be positively correlated with DA concentration in both animal groups. These findings offer new insights into DA dynamics in the context of circadian rhythm regulation, and the chronically reliable performance and dual measurement capability of this technology hold great potential for a broad range of neuroscience research.
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Affiliation(s)
- Bingchen Wu
- Department of BioengineeringUniversity of PittsburghPittsburghPA15213USA
- Center for the Neural Basis of CognitionPittsburghPA15213USA
| | - Elisa Castagnola
- Department of BioengineeringUniversity of PittsburghPittsburghPA15213USA
- Department of Biomedical EngineeringLouisiana Tech UniversityRustonLA71272USA
| | | | - Xinyan Tracy Cui
- Department of BioengineeringUniversity of PittsburghPittsburghPA15213USA
- Center for the Neural Basis of CognitionPittsburghPA15213USA
- McGowan Institute for Regenerative MedicinePittsburghPA15219USA
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4
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Li L, Jiang C, Li L. A Comparative Study on the Effect of Substrate Structure on Electrochemical Performance and Stability of Electrodeposited Platinum and Iridium Oxide Coatings for Neural Electrodes. MICROMACHINES 2023; 15:70. [PMID: 38258189 PMCID: PMC10821385 DOI: 10.3390/mi15010070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 12/20/2023] [Accepted: 12/27/2023] [Indexed: 01/24/2024]
Abstract
Implantable electrodes are crucial for stimulation safety and recording quality of neuronal activity. To enhance their electrochemical performance, electrodeposited nanostructured platinum (nanoPt) and iridium oxide (IrOx) have been proposed due to their advantages of in situ deposition and ease of processing. However, their unstable adhesion has been a challenge in practical applications. This study investigated the electrochemical performance and stability of nanoPt and IrOx coatings on hierarchical platinum-iridium (Pt-Ir) substrates prepared by femtosecond laser, compared with the coatings on smooth Pt-Ir substrates. Ultrasonic testing, agarose gel testing, and cyclic voltammetry (CV) testing were used to evaluate the coatings' stability. Results showed that the hierarchical Pt-Ir substrate significantly enhanced the charge-storage capacity of electrodes with both coatings to more than 330 mC/cm2, which was over 75 times that of the smooth Pt-Ir electrode. The hierarchical substrate could also reduce the cracking of nanoPt coatings after ultrasonic, agarose gel and CV testing. Although some shedding was observed in the IrOx coating on the hierarchical substrate after one hour of sonication, it showed good stability in the agarose gel and CV tests. Stable nanoPt and IrOx coatings may not only improve the electrochemical performance but also benefit the function of neurobiochemical detection.
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Affiliation(s)
- Linze Li
- School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou 350108, China
| | - Changqing Jiang
- National Engineering Research Center of Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing 100084, China
| | - Luming Li
- National Engineering Research Center of Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing 100084, China
- IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
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5
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Salavatian S, Robbins EM, Kuwabara Y, Castagnola E, Cui XT, Mahajan A. Real-time in vivo thoracic spinal glutamate sensing during myocardial ischemia. Am J Physiol Heart Circ Physiol 2023; 325:H1304-H1317. [PMID: 37737733 PMCID: PMC10908408 DOI: 10.1152/ajpheart.00299.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 09/18/2023] [Accepted: 09/18/2023] [Indexed: 09/23/2023]
Abstract
In the spinal cord, glutamate serves as the primary excitatory neurotransmitter. Monitoring spinal glutamate concentrations offers valuable insights into spinal neural processing. Consequently, spinal glutamate concentration has the potential to emerge as a useful biomarker for conditions characterized by increased spinal neural network activity, especially when uptake systems become dysfunctional. In this study, we developed a multichannel custom-made flexible glutamate-sensing probe for the large-animal model that is capable of measuring extracellular glutamate concentrations in real time and in vivo. We assessed the probe's sensitivity and specificity through in vitro and ex vivo experiments. Remarkably, this developed probe demonstrates nearly instantaneous glutamate detection and allows continuous monitoring of glutamate concentrations. Furthermore, we evaluated the mechanical and sensing performance of the probe in vivo, within the pig spinal cord. Moreover, we applied the glutamate-sensing method using the flexible probe in the context of myocardial ischemia-reperfusion (I/R) injury. During I/R injury, cardiac sensory neurons in the dorsal root ganglion transmit excitatory signals to the spinal cord, resulting in sympathetic activation that potentially leads to fatal arrhythmias. We have successfully shown that our developed glutamate-sensing method can detect this spinal network excitation during myocardial ischemia. This study illustrates a novel technique for measuring spinal glutamate at different spinal cord levels as a surrogate for the spinal neural network activity during cardiac interventions that engage the cardio-spinal neural pathway.NEW & NOTEWORTHY In this study, we have developed a new flexible sensing probe to perform an in vivo measurement of spinal glutamate signaling in a large animal model. Our initial investigations involved precise testing of this probe in both in vitro and ex vivo environments. We accurately assessed the sensitivity and specificity of our glutamate-sensing probe and demonstrated its performance. We also evaluated the performance of our developed flexible probe during the insertion and compared it with the stiff probe during animal movement. Subsequently, we used this innovative technique to monitor the spinal glutamate signaling during myocardial ischemia and reperfusion that can cause fatal ventricular arrhythmias. We showed that glutamate concentration increases during the myocardial ischemia, persists during the reperfusion, and is associated with sympathoexcitation and increases in myocardial substrate excitability.
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Affiliation(s)
- Siamak Salavatian
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Elaine Marie Robbins
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Yuki Kuwabara
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Elisa Castagnola
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Xinyan Tracy Cui
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
- Center for Neural Basis of Cognition, Pittsburgh, Pennsylvania, United States
- McGowan Institute for Regenerative Medicine, Pittsburgh, Pennsylvania, United States
| | - Aman Mahajan
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
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6
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Wu G, Zhang ET, Qiang Y, Esmonde C, Chen X, Wei Z, Song Y, Zhang X, Schneider MJ, Li H, Sun H, Weng Z, Santaniello S, He J, Lai RY, Li Y, Bruchas MR, Zhang Y. Long-Term In Vivo Molecular Monitoring Using Aptamer-Graphene Microtransistors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.18.562080. [PMID: 37905115 PMCID: PMC10614860 DOI: 10.1101/2023.10.18.562080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Long-term, real-time molecular monitoring in complex biological environments is critical for our ability to understand, prevent, diagnose, and manage human diseases. Aptamer-based electrochemical biosensors possess the promise due to their generalizability and a high degree of selectivity. Nevertheless, the operation of existing aptamer-based biosensors in vivo is limited to a few hours. Here, we report a first-generation long-term in vivo molecular monitoring platform, named aptamer-graphene microtransistors (AGMs). The AGM incorporates a layer of pyrene-(polyethylene glycol)5-alcohol and DNase inhibitor-doped polyacrylamide hydrogel coating to reduce biofouling and aptamer degradation. As a demonstration of function and generalizability, the AGM achieves the detection of biomolecules such as dopamine and serotonin in undiluted whole blood at 37 °C for 11 days. Furthermore, the AGM successfully captures optically evoked dopamine release in vivo in mice for over one week and demonstrates the capability to monitor behaviorally-induced endogenous dopamine release even after eight days of implantation in freely moving mice. The results reported in this work establish the potential for chronic aptamer-based molecular monitoring platforms, and thus serve as a new benchmark for molecular monitoring using aptamer-based technology.
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Affiliation(s)
- Guangfu Wu
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
- Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA
| | - Eric T. Zhang
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
- Center for Neurobiology of Addiction, Pain, and Emotion, University of Washington, Seattle, WA 98195, USA
| | - Yingqi Qiang
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
- Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA
| | - Colin Esmonde
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Florida State University, Tallahassee, FL 32306, USA
| | - Xingchi Chen
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Florida State University, Tallahassee, FL 32306, USA
| | - Zichao Wei
- Department of Chemistry, University of Connecticut, Storrs, CT 06269, USA
| | - Yang Song
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
- Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA
| | - Xincheng Zhang
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
- Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA
| | - Michael J. Schneider
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
| | - Huijie Li
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
- Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA
| | - He Sun
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
- Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA
| | - Zhengyan Weng
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
- Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA
| | - Sabato Santaniello
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
| | - Jie He
- Department of Chemistry, University of Connecticut, Storrs, CT 06269, USA
| | - Rebecca Y. Lai
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Yan Li
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Florida State University, Tallahassee, FL 32306, USA
| | - Michael R. Bruchas
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA 98195, USA
- Center for Neurobiology of Addiction, Pain, and Emotion, University of Washington, Seattle, WA 98195, USA
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Yi Zhang
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA
- Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA
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7
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Castagnola E, Robbins EM, Krahe DD, Wu B, Pwint MY, Cao Q, Cui XT. Stable in-vivo electrochemical sensing of tonic serotonin levels using PEDOT/CNT-coated glassy carbon flexible microelectrode arrays. Biosens Bioelectron 2023; 230:115242. [PMID: 36989659 PMCID: PMC10101938 DOI: 10.1016/j.bios.2023.115242] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 03/13/2023] [Accepted: 03/19/2023] [Indexed: 03/29/2023]
Abstract
Chronic sampling of tonic serotonin (5-hydroxytryptamine, 5-HT) concentrations in the brain is critical for tracking neurological disease development and the time course of pharmacological treatments. Despite their value, in vivo chronic multi-site measurements of tonic 5-HT have not been reported. To fill this technological gap, we batch-fabricated implantable glassy carbon (GC) microelectrode arrays (MEAs) onto a flexible SU-8 substrate to provide an electrochemically stable and biocompatible device/tissue interface. To achieve detection of tonic 5-HT concentrations, we applied a poly(3,4-ethylenedioxythiophene)/carbon nanotube (PEDOT/CNT) electrode coating and optimized a square wave voltammetry (SWV) waveform for selective 5-HT measurement. In vitro, the PEDOT/CNT-coated GC microelectrodes achieved high sensitivity to 5-HT, good fouling resistance, and excellent selectivity against the most common neurochemical interferents. In vivo, our PEDOT/CNT-coated GC MEAs successfully detected basal 5-HT concentrations at different locations within the CA2 region of the hippocampus of both anesthetized and awake mice. Furthermore, the PEDOT/CNT-coated MEAs were able to detect tonic 5-HT in the mouse hippocampus for one week after implantation. Histology reveals that the flexible GC MEA implants caused less tissue damage and reduced inflammatory response in the hippocampus compared to commercially available stiff silicon probes. To the best of our knowledge, this PEDOT/CNT-coated GC MEA is the first implantable, flexible sensor capable of chronic in vivo multi-site sensing of tonic 5-HT.
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Affiliation(s)
- Elisa Castagnola
- Department of Bioengineering, University of Pittsburgh, 3501 Fifth Ave. Pittsburgh, PA 15260, Pittsburgh, PA, USA; Department of Biomedical Engineering, Louisiana Tech University, Ruston, LA, 818 Nelson Ave, 71272, USA
| | - Elaine M Robbins
- Department of Bioengineering, University of Pittsburgh, 3501 Fifth Ave. Pittsburgh, PA 15260, Pittsburgh, PA, USA
| | - Daniela D Krahe
- Department of Bioengineering, University of Pittsburgh, 3501 Fifth Ave. Pittsburgh, PA 15260, Pittsburgh, PA, USA
| | - Bingchen Wu
- Department of Bioengineering, University of Pittsburgh, 3501 Fifth Ave. Pittsburgh, PA 15260, Pittsburgh, PA, USA; Center for Neural Basis of Cognition, University of Pittsburgh, 4400 Fifth Ave, PA 15213, Pittsburgh, PA, 15261, USA
| | - May Yoon Pwint
- Department of Bioengineering, University of Pittsburgh, 3501 Fifth Ave. Pittsburgh, PA 15260, Pittsburgh, PA, USA; Center for Neural Basis of Cognition, University of Pittsburgh, 4400 Fifth Ave, PA 15213, Pittsburgh, PA, 15261, USA
| | - Qun Cao
- Department of Bioengineering, University of Pittsburgh, 3501 Fifth Ave. Pittsburgh, PA 15260, Pittsburgh, PA, USA
| | - Xinyan Tracy Cui
- Department of Bioengineering, University of Pittsburgh, 3501 Fifth Ave. Pittsburgh, PA 15260, Pittsburgh, PA, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, 450 Technology Drive, Pittsburgh, PA, 15219-3110, USA; Center for Neural Basis of Cognition, University of Pittsburgh, 4400 Fifth Ave, PA 15213, Pittsburgh, PA, 15261, USA.
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8
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Salavatian S, Robbins EM, Kuwabara Y, Castagnola E, Cui XT, Mahajan A. Real-time in vivo thoracic spinal glutamate sensing reveals spinal hyperactivity during myocardial ischemia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.11.531911. [PMID: 36993301 PMCID: PMC10054946 DOI: 10.1101/2023.03.11.531911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Myocardial ischemia-reperfusion (IR) can cause ventricular arrhythmias and sudden cardiac death via sympathoexcitation. The spinal cord neural network is crucial in triggering these arrhythmias and evaluating its neurotransmitter activity during IR is critical for understanding ventricular excitability control. To assess the real-time in vivo spinal neural activity in a large animal model, we developed a flexible glutamate-sensing multielectrode array. To record the glutamate signaling during IR injury, we inserted the probe into the dorsal horn of the thoracic spinal cord at the T2-T3 where neural signals generated by the cardiac sensory neurons are processed and provide sympathoexcitatory feedback to the heart. Using the glutamate sensing probe, we found that the spinal neural network was excited during IR, especially after 15 mins, and remained elevated during reperfusion. Higher glutamate signaling was correlated with the reduction in the cardiac myocyte activation recovery interval, showing higher sympathoexcitation, as well as dispersion of the repolarization which is a marker for increased risk of arrhythmias. This study illustrates a new technique for measuring the spinal glutamate at different spinal cord levels as a surrogate for the spinal neural network activity during cardiac interventions that engage the cardio-spinal neural pathway. Graphical abstract
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9
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Castagnola E, Robbins EM, Krahe D, Wu B, Pwint MY, Cao Q, Cui XT. Implantable flexible multielectrode arrays for multi-site sensing of serotonin tonic levels. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.17.524488. [PMID: 36711655 PMCID: PMC9882191 DOI: 10.1101/2023.01.17.524488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Real-time multi-channel measurements of tonic serotonin (5-hydroxytryptamine, 5-HT) concentrations across different brain regions are of utmost importance to the understanding of 5-HT’s role in anxiety, depression, and impulse control disorders, which will improve the diagnosis and treatment of these neuropsychiatric illnesses. Chronic sampling of 5-HT is critical in tracking disease development as well as the time course of pharmacological treatments. Despite their value, in vivo chronic multi-site measurements of 5-HT have not been reported. To fill this technological gap, we batch fabricated implantable glassy carbon (GC) microelectrode arrays (MEAs) on a flexible SU-8 substrate to provide an electrochemically stable and biocompatible device/tissue interface. Then, to achieve multi-site detection of tonic 5-HT concentrations, we incorporated the poly(3,4-ethylenedioxythiophene)/functionalized carbon nanotube (PEDOT/CNT) coating on the GC microelectrodes in combination with a new square wave voltammetry (SWV) approach, optimized for selective 5-HT measurement. In vitro , the PEDOT/CNT coated GC microelectrodes achieved high sensitivity towards 5-HT, good fouling resistance in the presence of 5-HT, and excellent selectivity towards the most common neurochemical interferents. In vivo , our PEDOT/CNT-coated GC MEAs were able to successfully detect basal 5-HT concentrations at different locations of the CA2 hippocampal region of mice in both anesthetized and awake head-fixed conditions. Furthermore, the implanted PEDOT/CNT-coated MEA achieved stable detection of tonic 5-HT concentrations for one week. Finally, histology data in the hippocampus shows reduced tissue damage and inflammatory responses compared to stiff silicon probes. To the best of our knowledge, this PEDOT/CNT-coated GC MEA is the first implantable flexible multisite sensor capable of chronic in vivo multi-site sensing of tonic 5-HT. This implantable MEA can be custom-designed according to specific brain region of interests and research questions, with the potential to combine electrophysiology recording and multiple analyte sensing to maximize our understanding of neurochemistry. Highlights PEDOT/CNT-coated GC microelectrodes enabled sensitive and selective tonic detection of serotonin (5-HT) using a new square wave voltammetry (SWV) approach PEDOT/CNT-coated GC MEAs achieved multi-site in vivo 5-HT tonic detection for one week. Flexible MEAs lead to reduced tissue damage and inflammation compared to stiff silicon probes.
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