Periodic Reporting for period 1 - BIOMOSAIC (From Biopigments to BIOelectronics: MOdelling Semiconducting EumelAnin-based InterfaCes)
Periodo di rendicontazione: 2020-04-01 al 2022-03-31
Bioelectronic devices are being developed to treat diseases by electrical stimulation of nerves and replace drugs, avoiding their harmful side effects. Other applications are in monitoring and diagnostics, such as wearable glucose sensors for diabetes, or ingestible nanoelectronics to replace invasive unpleasant exams like gastroscopies.
Organic materials, due to their flexibility and low cost, are ideal candidates for bioelectronics applications; their mechanical, physical and chemical properties can be easily tailored to match those of different biological tissues. However, a systematic design and improvement of polymer semiconductors for OECTs is currently out of reach due to the lack of structure-properties relationships describing these mixed conductors.
While current efforts are mostly focused on adapting polymer semiconductors developed in organic electronics by making them more hydrophilic, these materials are rarely biocompatible and may have limited stability in water. A radically different approach is instead to exploit naturally biocompatible materials, enhancing their ionic and electronic conducting properties.
Eumelanin – the brown-black biopigment in our hair and skin responsible for protecting us from the effects of solar radiation, is a natural protonic and electronic conductor, and thus promising for bioelectronic applications. However, this pigment lacks a well defined chemical and supramolecular structure, making it difficult to systematically improve its conductive properties.
The overall aim of this project is to leverage computational chemistry tools to develop a model of eumelanin and related materials, promoting the development of structure-properties relationships and its future incorporation in biomedical electronic devices. The model will ultimately shed light on the limiting factors for conductivity in eumelanin, and enable the optimisation of eumelanin-based devices.
Organic materials, due to their flexibility and low cost, are ideal candidates for bioelectronics applications; their mechanical, physical and chemical properties can be easily tailored to match those of different biological tissues. However, a systematic design and improvement of polymer semiconductors for OECTs is currently out of reach due to the lack of structure-properties relationships describing these mixed conductors.
While current efforts are mostly focused on adapting polymer semiconductors developed in organic electronics by making them more hydrophilic, these materials are rarely biocompatible and may have limited stability in water. A radically different approach is instead to exploit naturally biocompatible materials, enhancing their ionic and electronic conducting properties.
Eumelanin – the brown-black biopigment in our hair and skin responsible for protecting us from the effects of solar radiation, is a natural protonic and electronic conductor, and thus promising for bioelectronic applications. However, this pigment lacks a well defined chemical and supramolecular structure, making it difficult to systematically improve its conductive properties.
The overall aim of this project is to leverage computational chemistry tools to develop a model of eumelanin and related materials, promoting the development of structure-properties relationships and its future incorporation in biomedical electronic devices. The model will ultimately shed light on the limiting factors for conductivity in eumelanin, and enable the optimisation of eumelanin-based devices.
Oligomers of eumelanin were described using a combination of DFT calculations (J. Phys. Chem. Lett. 2020, 11 (3), 1045–1051) and molecular dynamics simulations. A similar approach was also used for the polymer pg2T-T in a collaborative work including the fellow, a PhD student supervised by the fellow, and the McCulloch group (Chem. Mater. 2020, 32 (15), 6618–6628).
Atomistic molecular dynamics simulations were employed to study self assembly and proton conductivity pathways in eumelanin aggregates. Tautomerisation, proton exchange and hydrogen bonding sites were described by a numerical/probabilistic model that takes into account kinetic and thermodynamic data from experimental collaborators. A different polymer system (pg2T-T) was also studied in dry and wet conditions (Chem. Mater. 2020, 32 (17), 7301–7308), enabling the comparison of ion/proton transport across different materials.
Together with proton transfer networks, electronic transport pathways arising from DFT calculations enable to investigate limiting factors for protonic and electronic conductivity in eumelanin, and propose suitable chemical modifications to enhance protonic/electronic transport in the material.
Overall the project output includes 1 review (Chemical Reviews 2022, 122, 4, 4493–4551), 10 research seminars, 4 contributed talks at international and national conferences and the organisation of an online workshop (www.e-mat.org). Several drafts still in preparation to be submitted in the coming months. The wider impact of the project within the bioelectronics and melanin community can be measured by the range of dissemination activities that contributed to increase the international profile of the researcher.
Atomistic molecular dynamics simulations were employed to study self assembly and proton conductivity pathways in eumelanin aggregates. Tautomerisation, proton exchange and hydrogen bonding sites were described by a numerical/probabilistic model that takes into account kinetic and thermodynamic data from experimental collaborators. A different polymer system (pg2T-T) was also studied in dry and wet conditions (Chem. Mater. 2020, 32 (17), 7301–7308), enabling the comparison of ion/proton transport across different materials.
Together with proton transfer networks, electronic transport pathways arising from DFT calculations enable to investigate limiting factors for protonic and electronic conductivity in eumelanin, and propose suitable chemical modifications to enhance protonic/electronic transport in the material.
Overall the project output includes 1 review (Chemical Reviews 2022, 122, 4, 4493–4551), 10 research seminars, 4 contributed talks at international and national conferences and the organisation of an online workshop (www.e-mat.org). Several drafts still in preparation to be submitted in the coming months. The wider impact of the project within the bioelectronics and melanin community can be measured by the range of dissemination activities that contributed to increase the international profile of the researcher.
The project was transformative for the career trajectory of the fellow, and the fundamental study conducted here provided new information on the electronic properties, proton conduction and self-assembly of eumelanin-inspired polymers. Thes work contributed to renew the interest in eumelanin-inspired materials for bioelectronics. The collaborations started by the fellow during the project will be the cornerstone of her academic network and the basis for future joint funding bids. She is also exploring industrial partnerships aimed at establishing how the project results and any subsequent work can contribute to address industrial needs in the field of melanin-inspired electronics and bioelectronics.