The development of fluorescent, analyte-sensitive aerogels for space applications Alexandra Thomas and Veeren M. Chauhan University of Nottingham, UK Aerogels are thermally stable, optically transparent and are highly porous materials which can be paired with fluorescent sensing techniques to provide a new avenue to sensing and monitoring environmental changes within extra-terrestrial environments. Current potential applications of these fluorescent aerogels include pH and O 2 monitoring in hydroponics in space colonisation and exploration missions, atmospheric molecular sensors and high-energy particle capture from cosmic rays. However, the exact optimisations for these applications in varying extra-terrestrial environments are unknown. In this work, we report the successful fabrication of solid-state pH-sensitive fluorescent sensors based on a tetraethoxysilane framework conjugated with the pH-sensitive dyes 5(6)-carboxyfluorescein succinimidyl ester (FAM) and Oregon Green 488 (OG) followed by the precipitation of the sensor as characterised through fluorescent microscopy. From this, we have encapsulated the sensor within a silica matrix to form the fluorescent aerogel which requires further work to enhance its structural stability and sensing capabilities. Determined through fluorescent spectrophotometry, the rate of emission at λ = 517 - 520 nm is increased as the solution around the sensor increases in basicity. Relative sensor sizes were evaluated using dynamic light scattering (DLS) to 2 μm suggesting the formation of a microsensor however transmission electron microscopy indicated they are nanosensors. This discrepancy is thought to be due to the aggregation of nanoparticles in the DLS solution. Upon further synthesis and characterisation, we anticipate the potential success in implementing pH-sensitive fluorophores within aerogels to create a new, more versatile sensing material which could be further optimised for a wider-ranging pH sensor, a multi-analyte sensor or other space- based chemical sensors.
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