Stochastic electrochemistry for catalysis and analysis of carboneous bio-electrodes.

Project Information

STOCHELEC

Grant agreement ID: 844746

DOI

10.3030/844746

Project closed

EC signature date 10 April 2019

Start date 1 January 2020

End date 31 December 2021

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 184 707,84

EU contribution

€ 184 707,84

Coordinated by

INSTITUT POLYTECHNIQUE DE BORDEAUX
France

Periodic Reporting for period 1 - STOCHELEC (Stochastic electrochemistry for catalysis and analysis of carboneous bio-electrodes.)

Reporting period: 2020-01-01 to 2021-12-31

Summary of the context and overall objectives of the project

The STOCHELEC project (MSCA-IF agreement #844746), proposes an innovative solution to preserve the activity of biological catalysts at electrified interfaces, introducing the development of a 4th generation of bioelectrochemical sensors. In classic electrochemical biosensors, enzymes immobilized on an electrode as a self- assembled monolayer (SAM) are exposed to a strong and static electrical field disturbing their active 3D structure and thus often preventing free enzymes’ dynamics that leads to a loss of enzyme activity. In order to increase the lifetime of these biologically structured interfaces, one must adjust the polarization profile to the actual dynamics of the system being used.

The development of a 4th generation biosensors is necessary to benefit from the high activity and natural selectivity of biological entities combined with electronic transducers. Reaching these goals will allow monitoring precisely the concentration of specific biomarkers and triggering the redox reaction of important molecules and macro-molecules, controlling their activity in-vivo. These molecular architectures are of tremendous importance for the development of next generation biotechnological instruments including health sensors for point of care and implantable devices, and for energy conversion systems such as biofuel cells.

This project aimed to acquire more knowledge on long-term operational stability of bio-electrochemical systems. The long-term goal is to dynamically stimulate the electrochemical interface to preserve and to increase the operational stability and activity of those systems. The first objective is to establish a biocompatible electrified interface using renewable materials. We successfully synthesized and used fluorescent carbon nanoparticles whose biocompatible properties are establish, thus providing a promising basis for the development of implantable devices. The second objective was to study the influence of alternating electrical polarization waveform frequencies on the bio-electrochemical reaction yields, and thus to interrogate the validity of continuous polarization in bio-electrochemical sciences. The final goal of the proposal proposed a novel electroanalytical technic based on the stochastic stimulation of the electrical interface, mimicking thermal stochastic fluctuations.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Biocompatible carbon nanoparticles were successfully produced during the first period of the project and their use has been extended from the initial scope of the study. The first objective aiming to develop a biocompatible interface has been fully reached, thus providing a reliable method to immobilize the carbon nanoparticles onto a polycrystalline gold substrate. The in-depth characterization of the interface was carried out as planned using atomic force microscopy, high-resolution scanning electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analysis. The rich surface chemistry of the carbon nanoparticles was also exploited to compare the electrochemical response of biomolecules immobilized in an oriented manner on the gold electrode.

We extended the initial scope of the project to demonstrate the possibility to use these particles as unconventional catalysts for the hydrogen evolution reaction. The efficiency of the electrochemical reaction increased by 5 fold with a decrease of the activation energy by hundreds of millivolts. We used a oxygen reducing enzyme employed for the construction of biofuel cell applications and we revealed the influence of the AC frequency on the efficiency of the reaction. The enzymes activity increases by 2 fold under an optimum AC polarization frequency compared to that of a continuous operation mode. These results were obtained based on a successful collaboration with a neighboring institute and a research proposal was draft to ensure a proper follow-up of the work. For the purpose of the development of a biocompatible electrochemical interface, new types of fluorescent carbon nanoparticles, dopped with phosphate moieties, have been produced. These particles were used as a fluorescent sensing platform for hazardous chemicals such as copper ions and organic aromatic molecules. These nanoparticles are also an efficient crosslinking agent for the gelation of a chitosan polymer, and thus allowed the formation of fluorescent responsive hydrogels.

The fellow was able to present and to discuss the different aims and milestones of the research project within his research group amid the Covid 19 pandemy situation, offering multiple collaboration opportunities. The different studies carried out along the project were presented in the frame of an international congress on nanotechnologies (Nanomeet2021, Porto, Portugal). Finally, the Covid-19 pandemic has extended the delay of fabrication of the analytical apparatus allowing a precise frequency tuning on the signal imposed on the electrode/electrolyte interface, but the exploitation of the results is underway. The results of the studies carried out during the fellowship will be published in high impact journals after completion of three different manuscripts.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

This project succeeded in producing a custom-designed potentiostat that is able to polarize the electrochemical interface with an analog signal incorporating a well-defined set of sinusoidal AC waveforms, used to mimic thermal fluctuations at the electrochemical interface. This development was necessary because the performance required for the planned experiments is beyond the state-of-the-art equipment which can be found from commercial sources. The electric currents generated at the electrochemical interface have been studied with extremely high temporal resolution (MHz) thanks to the implementation of a powerful analogic to numeric signal converter. For the first time, the unambiguous polarization of the electrochemical interface with stochastic signals has been studied, and could challenge the validity of continuous polarization waveforms used in (bio-)electrochemical sciences.

The project establishes a practical base to bridge the field of biochemistry, used to extract kinetical constants of enzymes dynamics, and the field of electrochemistry which serves for activating the catalyst. The development of a 4th generation biosensors, based on the non-ambiguous polarization of the (bio-)electrochemical interface, will allow to preserve the biological material at the electrified interface, and to increase by several fold the lifetime of biofuel cells and and bioelectrochemcial sensors.

Last-but-not-least, the EU-funded MSCA action #844746 allowed the fellow to initiate and to work on the development of a new electroanalytical device. Integrating a stimulating environment allowed him to enlarge his scientific network within the research group and more generally within the Bordeaux research campus. He acquired new skills and techniques relative to the development of electroanalytical techniques that will be used in his future academic career. The management of an instrumental co-development in interaction with a company and the supervision of a student during the project ensure the fellow the necessary skills to organize and to lead a research group in an academic institution.

Scanning electron microscopy of electrodeposited carbon nanoparticles