PFI-TT: Achieving efficient production of visible light from semiconductor nanocrystals in water

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The broader impact/commercial potential of this Partnerships for Innovation - Technology Translation (PFI-TT) project is a nanocrystal-based light absorber that converts near infrared (NIR) to visible light in biologically friendly aqueous media. This project addresses unmet needs in the life sciences where the deep targeted delivery of light to tissue is needed because it is currently impossible deliver violet light deep inside living mammals without surgery or using a very intense laser that exceeds the mammalian pain threshold. This project will advance the development of a prototype system. The ability to deliver violet light non-invasively centimeters below the skin will facilitate new ways to detect oxygen (hypoxia) and create inexpensive light sources for point-of-care (POC) diagnostics. Potential commercial applications include mapping neural networks, mitigating pain, artificially controlling the circadian rhythm, alleviating depression, and imaging physiological processes in preclinical research. Apart from impact in these large and growing billion-dollar markets, this innovation will enable new directions in the diverse academic fields of neuroscience, light-sheet imaging and circadian rhythm research. The proposed project will establish novel methods for stabilizing hydrophobic nanocrystals and molecular antennas in water. The goals are to realize state-of-the art photon upconversion quantum yields with this hybrid platform in aqueous media, as opposed to previous records in organic solvent. Research objectives include establishing a kinetic or thermodynamic barrier that isolates the semiconductor nanocrystals and molecular emitters from their aqueous surroundings while preventing quenching by ambient oxygen. The nano- or micro-vesicles or emulsions proposed here will be stabilized by fine-tuning the relative ratios of various components and their differing solubilities. The spin-triplet excited state necessary for high photon upconversion quantum yields will be protected against undesired quenching by oxygen with chemical barriers or additives.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.