2 research outputs found
Antimicrobial Amino-Functionalized Nitrogen-Doped Graphene Quantum Dots for Eliminating Multidrug-Resistant Species in Dual-Modality Photodynamic Therapy and Bioimaging under Two-Photon Excitation
Developing
a nanomaterial, for use in highly efficient dual-modality
two-photon photodynamic therapy (PDT) involving reactive oxygen species
(ROS) generation and for use as a two-photon imaging contrast probe,
is currently desirable. Here, graphene quantum dots (GQDs) doped with
nitrogen and functionalized with an amino group (amino-N-GQDs) serving
as a photosensitizer in PDT had the superior ability to generate ROS
as compared to unmodified GQDs. Multidrug-resistant (MDR) species
were completely eliminated at an ultralow energy (239.36 nJ pixel<sup>–1</sup>) through only 12 s two-photon excitation (TPE) in
the near-infrared region (800 nm). Furthermore, the amino-N-GQDs had
an absorption wavelength of approximately 800 nm, quantum yield of
0.33, strong luminescence, an absolute cross section of approximately
54 356 Göeppert–Mayer units, a lifetime of 1.09
ns, a ratio of the radiative to nonradiative decay rates of approximately
0.49, and high two-photon stability under TPE. These favorable properties
enabled the amino-N-GQDs to act as a two-photon contrast probe for
tracking and localizing analytes through in-depth two-photon imaging
in a three-dimensional biological environment and concurrently easily
eliminating MDR species through PDT
Structural characterization and immunosuppressive activity of a new pregnane glycoside from <i>Epigynum cochinchinensis</i>
<p>Phytochemical investigation on the ethyl acetate fraction of the leaves of <i>Epigynum cochinchinensis</i> led to the isolation of a new C<sub>21</sub> pregnane glycoside, epigycoside B (<b>1</b>), together with three known analogues. Their structures were elucidated on the basis of extensive spectroscopic techniques, including UV, MS, and NMR experiments, as well as the chemical methods. Compound <b>1</b> displayed <i>in vitro</i> immunosuppressive activity against concanavalin A (Con A)/Lipopolysaccharides (LPS)-stimulated proliferation of mice splenocyte. The activity was significant as compared with control group at 50 <i>μ</i>M concentration.</p