Browsing by Author "Tang, Juan"

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    Oxime as a general photocage for the design of visible light photo-activatable fluorophores
    (Royal Society of Chemistry, 2021) Wang, Lushun; Wang, Shichao; Tang, Juan; Espinoza, Vanessa B.; Loredo, Axel; Tian, Zeru; Weisman, R. Bruce; Xiao, Han
    Photoactivatable fluorophores have been widely used for tracking molecular and cellular dynamics with subdiffraction resolution. In this work, we have prepared a series of photoactivatable probes using the oxime moiety as a new class of photolabile caging group in which the photoactivation process is mediated by a highly efficient photodeoximation reaction. Incorporation of the oxime caging group into fluorophores results in loss of fluorescence. Upon light irradiation in the presence of air, the oxime-caged fluorophores are oxidized to their carbonyl derivatives, restoring strong fluorophore fluorescence. To demonstrate the utility of these oxime-caged fluorophores, we have created probes that target different organelles for live-cell confocal imaging. We also carried out photoactivated localization microscopy (PALM) imaging under physiological conditions using low-power light activation in the absence of cytotoxic additives. Our studies show that oximes represent a new class of visible-light photocages that can be widely used for cellular imaging, sensing, and photo-controlled molecular release.
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    Single-atom replacement as a general approach towards visible-light/near-infrared heavy-atom-free photosensitizers for photodynamic therapy
    (Royal Society of Chemistry, 2020) Tang, Juan; Wang, Lushun; Loredo, Axel; Cole, Carson C.; Xiao, Han
    Photodynamic therapy has become an emerging strategy for the treatment of cancer. This technology relies on the development of photosensitizers (PSs) that convert molecular oxygen to cytotoxic reactive oxygen species upon exposure to light. In this study, we have developed a facile and general strategy for obtaining visible light/near-infrared-absorbing PSs by performing a simple sulfur-for-oxygen replacement within existing fluorophores. Thionation of carbonyl groups within existing fluorophore cores leads to an improvement of the singlet oxygen quantum yield and molar absorption coefficient at longer wavelengths (deep to 600–800 nm). Additionally, these thio-based PSs lack dark cytotoxicity but exhibit significant phototoxicity against monolayer cancer cells and 3D multicellular tumor spheroids with IC50 in the micromolar range. To achieve tumor-specific delivery, we have conjugated these thio-based PSs to an antibody and demonstrated their tumor-specific therapeutic activity.
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    Visible light-activated dyes and methods of use thereof
    (2024-02-27) Xiao, Han; Tang, Juan; Rice University; United States Patent and Trademark Office
    Disclosed herein are photoactivable fluorophores comprising one or more thiocarbonyl groups as well as conjugates and compositions thereof. The present disclosure also provides methods of preparing photoactivatable fluorophores as well as methods of imaging using the photoactivatable fluorophores, conjugates, and compositions of the present disclosure.