The fluorescent markers based on oxazolopyridine unit for imaging organelles.

Bioactive oxazolopyridine unit was used in the synthesis of fluorescent markers for specific organelles in this paper. The compounds 1a-c are linked with double bond between oxazolopyridine ring and photogenic precursors (3a-c). Compound 1a showed higher fluorescence yield (0.86 in THF), compounds 1b-c showed larger stokes shifts in DMSO. In lipid vesicles environment, they also showed good optical properties. In addition, the three compounds are biomarkers with lower cytotoxicity. Among them, compound 1a based on oxazolopyridine and coumarin unit is a dual targetable fluorescent marker for mitochondria and lipid droplets; while the other two compounds 1b-c are only biomarkers for lipid droplets.

Photoactivatable Prodrug of Doxazolidine Targeting Exosomes.

Natural lipid nanocarriers, exosomes, carry cell-signaling materials such as DNA and RNA for intercellular communications. Exosomes derived from cancer cells contribute to the progression and metastasis of cancer cells by transferring oncogenic signaling molecules to neighboring and remote premetastatic sites. Therefore, applying the unique properties of exosomes for cancer therapy has been expected in science, medicine, and drug discovery fields. Herein, we report that an exosome-targeting prodrug system, designated MARCKS-ED-photodoxaz, could spatiotemporally control the activation of an exquisitely cytotoxic agent, doxazolidine (doxaz), with UV light. The MARCKS-ED peptide enters a cell by forming a complex with the exosomes in situ at its plasma membrane and in the media. MARCKS-ED-photodoxaz releases doxaz under near-UV irradiation to inhibit cell growth with low nanomolar IC50 values. The MARCKS-ED-photodoxaz system targeting exosomes and utilizing photochemistry will potentially provide a new approach for the treatment of cancer, especially for highly progressive and invasive metastatic cancers.

Theoretical Studies on the Photochemistry of Pentose Aminooxazoline, a Hypothetical Intermediate Product in the Prebiotic Synthetic Scenario of RNA Nucleotides.

2-Aminooxazole is generally considered a prebiotic precursor of ribonucleotides on the early earth. Its pentose compound, pentose aminooxazoline, has been suggested to be a key intermediate in the prebiotic synthetic scenario. In this article, detailed mechanism of the photochemistry of pentose aminooxazoline has been studied by performing density functional theory and multireference complete active space self-consistent field calculations. Parallel to the "ring-puckering" process, which leads to ultrafast nonradiative deactivation, several other photodissociation channels are explored in detail. In addition, the influences of the pentose structure and solvation effects with both implicit and explicit water models have been uncovered for both neutral and protonated forms. The current theoretical results provide very important information not only for the photostability of RNA nucleotides but also for an in-depth understanding of the synthesis of other prebiotic nucleotides.

Synthesis and microwave assisted polymerization of fluorinated 2-phenyl-2-oxazolines: the fastest 2-oxazoline monomer to date.

The living cationic ring-opening polymerization of 2-oxazolines with fluorinated aromatic substituents was found to be strongly accelerated by o-fluoro substituents.