Herein, we present
high-yielding, concise access to a set of xanthenium-derived,
water-soluble, low-molecular-weight photocages allowing light-controlled
cargo release in the green to red region. Very importantly, these
new photocages allow installation of various payloads through ester,
carbamate, or carbonate linkages even at the last stage of the synthesis.
Payloads were uncaged with high efficiency upon green, orange, or
red light irradiation, leading to the release of carboxylic acids,
phenols, and amines. The near-ideal properties of a carboxanthenium
derivative were further evaluated in the context of light-controlled
drug release using a camptothecin-derived chemotherapeutic drug, SN38.
Notably, the caged drug showed orders of magnitude lower efficiency in cellulo, which was reinstated after red light irradiation.
The presented photocages offer properties that facilitate the translation
of photoactivated chemotherapy toward clinical applications.
Two sets of bioorthogonally applicable, double fluorogenic probes, capable of sensing DNA–protein interactions, were prepared by installing an azide or tetrazine motif onto structurally fluorogenic, DNA sensitive frames. Installation of these bioorthogonal functions onto DNA intercalating dyes furnished these scaffolds with reactivity based fluorogenicity, rendering these probes double-fluorogenic, AND-type logic switches that require the simultaneous occurrence of a bioorthogonal reaction and interaction with DNA to trigger high intensity fluorescence. The probes were evaluated for double fluorogenic behavior in the presence/absence of DNA and a complementary bioorthogonal function. Our studies revealed that azide and tetrazine appending thiazole orange frames show remarkable double fluorogenic features. One of these probes, a membrane permeable tetrazine modified thiazole orange derivative was further tested in live cell labeling studies. Cells expressing bioorthogonalized DNA-binding proteins showed intensive fluorescence characteristics of the localization of the proteins upon treatment with our double fluorogenic probe. On the contrary, labeling similarly bioorthogonalized cytosolic proteins did not result in the appearance of the fluorescence signal. These studies suggest that such double-fluorogenic probes are indeed capable of sensing DNA–protein interactions in cells.
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