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Development of novel luminescent oxygen sensing platforms for assessing microbial metabolism
Saccomano, Samuel C.
Saccomano, Samuel C.
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2025
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Saccomano_mines_0052E_13032.pdf
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- Embargoed until 2026-11-11
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2026-11-11
Abstract
Molecular oxygen is a fundamental component in cellular and microbial communities and an important indicator of their health and metabolic activity. Optical nanoparticle-based sensors (nanosensors) possess excellent tunability serving as a promising platform to capture the complex oxygen dynamics in various systems. We have developed three novel oxygen nanosensors with unique properties for improved oxygen sensing in biological applications.
First, we developed a ratiometric near-infrared emitting (600-800 nm) oxygen nanosensor to overcome autofluorescent signal within complex matrices. We translated this sensor to a high-throughput assay for monitoring oxygen in microcultures of Saccharomyces cerevisiae enabling us to screen metabolic activity under various conditions.
Next, we developed a fabrication method for fully covalent oxygen nanosensors to overcome the issues of dye leaching and particle aggregation present in other emulsion-based nanoparticle sensors. We used easily scalable bioconjugation methods, with branched polyethylenimine as the scaffold, to develop a sensor that could withstand autoclave conditions in a small-scale (200 mL) bioreactor vessel, allowing for contamination-free oxygen tracking in this system.
Finally, in a field dominated by oxygen probes with long luminescence lifetimes (>500 ns), we have developed a short-lifetime oxygen sensor using an exciplex-based dye pair with a charge-transfer quenching mechanism. By coupling anthracene and aniline moieties with a C3 linker and encapsulating them in polymeric nanoparticles, we achieved a ~30-60 ns lifetime sensor with good sensitivity and stability in aqueous environments.
Each advancement represents a new platform for oxygen sensing in biological applications. High-throughput metabolic assays could be expanded to screen growth conditions in diverse systems such as bacteria, tissue and other genetically diverse strains of yeast. Our scaffold-based sensors are ideal for systems like Saccharomyces cerevisiae, but optimization of conjugation reagents would improve cost efficiency and general functionality toward other systems. Exciplex-based sensors are suited for applications such as FLIM which require fast-lifetime probes for optimal resolution. Discovery of other oxygen-sensitive exciplexes could lead to new sensors with improved spectral properties.
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