Peptide and protein self-assembly in non-conventional solvents as ionic liquids gives rise to new materials. These present properties distinct from the corresponding water-based assemblies, namely molecular recognition towards analytes, air-stability and transduction potential. We explored small peptides, and structural proteins (gelatin and fibroin) to develop ionomaterials which were used as sensors in artificial olfaction [1], with unraveled possibilities in soft and flexible electronics. We further developed the concept of hybrid gels that result from the co-assembly of functional components – liquid crystals for reporting, ionic liquid as solvent, protein as matrix - which give rise to molecular recognition properties towards volatile organic compounds (VOCs) not seen in the individual components. When casting the hybrid gels as thin films, they exhibited dual optical and electrical stimuli-responsive properties in the presence of VOCs. Films of hybrid gels are studied as gas sensing materials in a custom-built electronic nose, supported by a dedicated automatic classifier based on support vector machines for data processing [2]. It is also possible to employ deep convolutional neural networks (CNN) as pattern recognition systems to analyse optical textures in liquid crystal-droplets exposed to a set of different VOCs [4]. Furthermore, we show that the developed device can be used in dry and humid conditions, for environmental, food and medical applications [3,5]. 

Acknowledgments: The authors acknowledge funding from European Research Council under the EU Horizon 2020 research and innovation programme (Grant Agreement No. SCENT-ERC-2014-STG-639123, 2015-2022 and Grant Agreement No. 101069405-ENSURE-ERC-2022-POC1)) and from Fundação para a Ciência e Tecnologia, I.P. (FCT), in the scope of the project PTDC/CTM-CTM/3389/2021, CPCA/15912/2022, UIDP/04378/2020 and UIDB/04378/2020 of the Research Unit on Applied Molecular Biosciences – UCIBIO and the project LA/P/0140/2020 of the Associate Laboratory Institute for Health and Bioeconomy – i4HB and the project, and the support of INCD funded by FCT and FEDER under the project 01/SAICT/2016 nº 02215.

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