Personne : Picard-Lafond, Audrey
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Picard-Lafond
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Audrey
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Université Laval. Département de chimie
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ncf11907619
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Publication Accès libre A metal-enhanced Hg2+-responsive fluorescent nanoprobe: from morphological design to application to natural waters(American Chemical Society, 2022-06-22) Picard-Lafond, Audrey; Boudreau, Denis; Larivière, DominicMetal-enhanced fluorescence (MEF) is a powerful tool in the design of sensitive chemical sensors by improving brightness and photostability to target-responsive fluorophores. Compounding these advantages with the modest hardware requirements of fluorescent sensing compared to that of centralized elemental analysis instruments, expanding the use of MEF to the detection of low-level inorganic pollutants is a compelling aspiration. Among the latter, monitoring mercury in the environment, where some of its species disseminate through the food chain and, in time, to humans, has elicited a broad research effort towards the development of Hg2+-responsive fluorescent sensors. Herein, a Hg2+-sensitive MEF-enabled probe was conceived by grafting a Hg2+-responsive fluorescein derivative to concentric Ag@SiO2 NPs, where the metallic core enhances fluorescent emission of molecular probes embedded in a surrounding silica shell. Time-resolved fluorescence measurements showed that the fluorophore’s excited state lifetime decreases from 3.9 ns in a solid, coreless silica sphere, to 0.4 ns in the core-shell nanoprobe, granting the dye a better resistance to photobleaching. The Ag-core system showed a sizable improvement in limit of detection at 2 nM (0.4 ppb) compared to 50 nM (10 ppb) in the silica-only colloids and its effectiveness for natural water analysis was demonstrated. Overall, the reported nanoarchitecture hints at the potential of MEF for heavy metal detection by fluorescence detection.Publication Accès libre Revealing the hydrolysis mechanism of a Hg2+-reactive fluorescein probe : novel insights on thionocarbonated dyes(American Chemical Society, 2019-12-31) Picard-Lafond, Audrey; Boudreau, Denis; Larivière, DominicAs one of the most toxic metal pollutants, mercury is the subject of extensive research to improve current detection strategies, notably to develop sensitive, selective, fast, and affordable Hg2+-responsive fluorescent probes. Comprehending the sensing mechanism of these molecules is a crucial step in their design and optimization of their performance. Herein, a new fluorescein-based thionocarbonate-appended Hg2+-sensitive probe was synthesized to study the hydrolysis reactions involved in the sensing process. Autohydrolysis was revealed as a significant component of the signal generation mechanism, occurring concurrently with Hg2+-catalyzed hydrolysis. This knowledge was used to investigate the effects of key experimental conditions (pH, temperature, chloride ions) on sensing efficiency. Overall, the chemical and physical properties of this new thionocarbonated dye and the insights into its sensing mechanism will be instrumental in designing reliable and effective portable sensing strategies for mercury and other heavy metals.