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Macdonald AR, Charlton F, Corrigan DK. Accelerating the development of implantable neurochemical biosensors by using existing clinically applied depth electrodes. Anal Bioanal Chem 2023; 415:1137-1147. [PMID: 36456747 PMCID: PMC9899734 DOI: 10.1007/s00216-022-04445-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/12/2022] [Accepted: 11/16/2022] [Indexed: 12/05/2022]
Abstract
In this study, an implantable stereo-electroencephalography (sEEG) depth electrode was functionalised with an enzyme coating for enzyme-based biosensing of glucose and L-glutamate. This was done because personalised medicine could benefit from active real-time neurochemical monitoring on small spatial and temporal scales to further understand and treat neurological disorders. To achieve this, the sEEG depth electrode was characterised using cyclic voltammetry (CV), differential pulse voltammetry (DPV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) using several electrochemical redox mediators (potassium ferri/ferrocyanide, ruthenium hexamine chloride, and dopamine). To improve performance, the Pt sensors on the sEEG depth electrode were coated with platinum black and a crosslinked gelatin-enzyme film to enable enzymatic biosensing. This characterisation work showed that producing a useable electrode with a good electrochemical response showing the expected behaviour for a platinum electrode was possible. Coating with Pt black improved the sensitivity to H2O2 over unmodified electrodes and approached that of well-defined Pt macro disc electrodes. Measured current showed good dependence on concentration, and the calibration curves report good sensitivity of 29.65 nA/cm2/μM for glucose and 8.05 nA/cm2/μM for L-glutamate with a stable, repeatable, and linear response. These findings demonstrate that existing clinical electrode devices can be adapted for combined electrochemical and electrophysiological measurement in patients and obviate the need to develop new electrodes when existing clinically approved devices and the associated knowledge can be reused. This accelerates the time to use and application of in vivo and wearable biosensing for diagnosis, treatment, and personalised medicine.
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Affiliation(s)
- Alexander R Macdonald
- Department of Biomedical Engineering, University of Strathclyde, 106 Rottenrow East, Glasgow, UK
| | - Francessca Charlton
- Department of Biomedical Engineering, University of Strathclyde, 106 Rottenrow East, Glasgow, UK
| | - Damion K Corrigan
- Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, UK.
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Williams HJ, Shipley JR, Rutz C, Wikelski M, Wilkes M, Hawkes LA. Future trends in measuring physiology in free-living animals. Philos Trans R Soc Lond B Biol Sci 2021; 376:20200230. [PMID: 34176330 PMCID: PMC8237165 DOI: 10.1098/rstb.2020.0230] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/18/2021] [Indexed: 02/07/2023] Open
Abstract
Thus far, ecophysiology research has predominantly been conducted within controlled laboratory-based environments, owing to a mismatch between the recording technologies available for physiological monitoring in wild animals and the suite of behaviours and environments they need to withstand, without unduly affecting subjects. While it is possible to record some physiological variables for free-living animals using animal-attached logging devices, including inertial-measurement, heart-rate and temperature loggers, the field is still in its infancy. In this opinion piece, we review the most important future research directions for advancing the field of 'physiologging' in wild animals, including the technological development that we anticipate will be required, and the fiscal and ethical challenges that must be overcome. Non-invasive, multi-sensor miniature devices are ubiquitous in the world of human health and fitness monitoring, creating invaluable opportunities for animal and human physiologging to drive synergistic advances. We argue that by capitalizing on the research efforts and advancements made in the development of human wearables, it will be possible to design the non-invasive loggers needed by ecophysiologists to collect accurate physiological data from free-ranging animals ethically and with an absolute minimum of impact. In turn, findings have the capacity to foster transformative advances in human health monitoring. Thus, we invite biomedical engineers and researchers to collaborate with the animal-tagging community to drive forward the advancements necessary to realize the full potential of both fields. This article is part of the theme issue 'Measuring physiology in free-living animals (Part II)'.
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Affiliation(s)
- H. J. Williams
- Department of Migration, Max Planck Institute of Animal Behavior, 78315 Radolfzell, Germany
- Department of Biology, University of Konstanz, Universitätsstraße 10, 78464, Konstanz, Germany
| | - J. Ryan Shipley
- Department of Migration, Max Planck Institute of Animal Behavior, 78315 Radolfzell, Germany
- Department of Biology, University of Konstanz, Universitätsstraße 10, 78464, Konstanz, Germany
| | - C. Rutz
- Centre for Biological Diversity, School of Biology, University of St Andrews, St Andrews KY16 9TH, UK
| | - M. Wikelski
- Department of Migration, Max Planck Institute of Animal Behavior, 78315 Radolfzell, Germany
- Department of Biology, University of Konstanz, Universitätsstraße 10, 78464, Konstanz, Germany
- Centre for the Advanced Study of Collective Behaviour, University of Konstanz, 78457 Konstanz, Germany
| | - M. Wilkes
- Extreme Environments Research Group, University of Portsmouth, Spinnaker Building, Cambridge Road, Portsmouth PO1 2EF, UK
| | - L. A. Hawkes
- Hatherly Laboratories, University of Exeter, College of Life and Environmental Sciences, Exeter EX4 4PS, UK
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Hawkes LA, Fahlman A, Sato K. What is physiologging? Introduction to the theme issue, part 2. Philos Trans R Soc Lond B Biol Sci 2021; 376:20210028. [PMID: 34176329 PMCID: PMC8237167 DOI: 10.1098/rstb.2021.0028] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2021] [Indexed: 01/05/2023] Open
Abstract
The physiological mechanisms by which animals regulate energy expenditure, respond to stimuli and stressors, and maintain homeostasis at the tissue, organ and whole organism levels can be described by 'physiologging'-that is, the use of onboard miniature electronic devices to record physiological metrics of animals in captivity or free-living in the wild. Despite its origins in the 1960s, physiologging has evolved more slowly than its umbrella field of biologging. However, the recording of physiological metrics in free-living animals will be key to solving some of the greatest challenges in biodiversity conservation, issues pertaining to animal health and welfare, and for inspiring future therapeutic strategies for human health. Current physiologging technologies encompass the measurement of physiological variables such as heart rate, brain activity, body temperature, muscle stimulation and dynamic movement, yet future developments will allow for onboard logging of metrics relating to organelle, molecular and genetic function. This article is part of the theme issue 'Measuring physiology in free-living animals (Part II)'.
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Affiliation(s)
- L. A. Hawkes
- University of Exeter, Hatherly Laboratories, Prince of Wales Road, Exeter, EX4 4PS, UK
| | - A. Fahlman
- Global Diving Research Inc. Ottawa ON K2J 5E8, USA
| | - K. Sato
- Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba Prefecture 277-8564, Japan
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