The development of highly efficient bioorthogonal reactions is of paramount importance for the research fields of biomaterials and chemical biology. We found that the o,o'-difluorinated aromatic azide was able to react with triphenylphosphine to produce water-stable phosphanimine. To further improve the efficiency of this kind of nonhydrolysis Staudinger reaction, a tetrafluorinated aromatic azide was employed to develop a faster nonhydrolysis Staudinger reaction with a rate of up to 51 m s , as revealed by high-performance liquid chromatography (HPLC) analysis and fluorescence kinetics. As a proof-of-concept study, the highly efficient Staudinger reaction was successfully used for chemoselective fluorescence labeling of proteins and nucleic acids (DNA and RNA) as well as for protein polyethyleneglycol (PEG)ylation. We believe that this bioorthogonal reaction can provide a broadly useful tool for various bioconjugations.
The
importance of selenium (Se) in biology and health has become
increasingly clear. Hydrogen selenide (H2Se), the biologically
available and active form of Se, is suggested to be an emerging nitric
oxide (NO)-like signaling molecule. Nevertheless, the
research on H2Se chemical biology has technique difficulties
due to the lack of well-characterized and controllable H2Se donors under physiological conditions, as well as a robust assay
for direct H2Se quantification. Motivated by these needs,
here, we demonstrate that selenocyclopropenones and selenoamides are
tunable donor motifs that release H2Se upon reaction with
cysteine (Cys) at pH 7.4 and that structural modifications enable
the rate of Cys-mediated H2Se release to be tuned. We monitored
the reaction pathways for the H2Se release and confirmed
H2Se generation qualitatively using different methods.
We further developed a quantitative assay for direct H2Se trapping and quantitation in an aqueous solution, which should
also be operative for investigating future H2Se donor motifs.
In addition, we demonstrate that arylselenoamide has the capability
of Cys-mediated H2Se release in cellular environments.
Importantly, mechanistic investigations and density functional theory
(DFT) calculations illustrate the plausible pathways of Cys-activated
H2Se release from arylselenoamides in detail, which may
help understand the mechanistic issues of the H2S release
from pharmacologically important arylthioamides. We anticipate that
the well-defined chemistries of Cys-activated H2Se donor
motifs will be useful for studying Se biology and for development
of new H2Se donors and bioconjugate techniques.
Hydrogen sulfide (H2S) is an endogenously produced gaseous signaling molecule with multiple biological functions. To visualize the endogenous in situ production of H2S in real time, new coumarin- and boron-dipyrromethene-based fluorescent turn-on probes were developed for fast sensing of H2S in aqueous buffer and in living cells. Introduction of a fluoro group in the ortho position of the aromatic azide can lead to a greater than twofold increase in the rate of reaction with H2S. On the basis of o-fluorinated aromatic azides, fluorescent probes with high sensitivity and selectivity toward H2S over other biologically relevant species were designed and synthesized. The probes can be used to in situ to visualize exogenous H2S and D-cysteine-dependent endogenously produced H2S in living cells, which makes them promising tools for potential applications in H2S biology.
Gene therapy offers an alternative and promising avenue to lung cancer treatment. Here, we used dibenzocyclooctyne (DBCO)-branched primers to construct a PTEN gene nanovector (NP-PTEN) through branch-PCR. NP-PTEN showed the nanoscale structure with biocompatible size (84.7 � 11.2 nm) and retained the improved serum stability compared to linear DNA. When transfected into NCI-H1299 cancer cells, NP-PTEN could overexpress PTEN protein to restore PTEN functions through the deactivation of PI3K-AKT-mTOR signaling pathway to inhibit cell proliferation and induce cell apoptosis. The apoptosis rate of NCI-H1299 cancer cells could reach up to 54.5 % � 4.6 % when the transfection concentration of NP-PTEN was 4.0 μg/mL. In mice bearing NCI-H1299 tumor xenograft intratumorally administrated with NP-PTEN, the average tumor volume and tumor weight was separately reduced by 61.7 % and 63.9 %, respectively, compared with the PBS group on the 18 th day of administration. The anticancer efficacy of NP-PTEN in NCI-H1299 tumor xenograft suggests the promising therapeutic potential of branch-PCR assembled PTEN gene nanovectors in lung cancer gene therapy and also provided more opportunities to introduce two or more tumor suppressor genes as an all-in-one gene nanovector for multiple gene-based cancer gene therapy.
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