7 research outputs found
Plume-ridge interactions: ridgeward versus plate-drag plume flow
The analysis of mid-ocean ridges and hotspots that are sourced by deep-rooted mantle plumes allows us to get a glimpse of mantle structure and dynamics. Dynamical interaction between ridge and plume processes have been widely proposed and studied, particularly in terms of ridgeward plume flow. However, the effects of plate drag on plume-lithosphere and plume-ridge interaction remain poorly understood. In particular, the mechanisms that control plume flow towards vs. away from the ridge have not yet been systematically studied. Here, we use 2D thermomechanical numerical models of plume-ridge interaction to systematically explore the effects of (i) ridge-spreading rate, (ii) initial plume head radius and (iii) plume-ridge distance. Our numerical experiments suggest two different geodynamic regimes: (1) plume flow towards the ridge is favored by strong buoyant mantle plumes, slow spreading rates and small plume-ridge distances; (2) plume drag away from the ridge is in turn promoted by fast ridge spreading for small-To-intermediate plumes and large plume-ridge distances. We find that the pressure gradient between the buoyant plume and spreading ridge at first drives ridgeward flow, but eventually the competition between plate drag and the gravitational force of plume flow along the base of the sloping lithosphere controls the fate of plume (spreading towards vs. away from the ridge). Our results highlight that fast-spreading ridges exert strong plate-dragging force, which sheds new light on natural observations of largely absent plume-lithosphere interaction along fast-spreading ridges, such as the East Pacific Rise
MoS<sub>2</sub> Quantum Dot@Polyaniline Inorganic–Organic Nanohybrids for in Vivo Dual-Modal Imaging Guided Synergistic Photothermal/Radiation Therapy
In this study, we introduce a versatile
nanomaterial based on MoS<sub>2</sub> quantum dot@polyaniline (MoS<sub>2</sub>@PANI) inorganic–organic nanohybrids, which exhibit
good potential to not only enhance photoaccoustic (PA) imaging/X-ray
computed tomography (CT) signal but also perform efficient radiotherapy
(RT)/photothermal therapy (PTT) of cancer. Upon the intravenous injection
of MoS<sub>2</sub>@PANI hybrid nanoparticles, the in vivo tumor could
be precisely positioned and thoroughly eliminated under the PA/CT
image-guided combination therapy of PTT/RT. This versatile nanohybrid
could show good potential to facilitate simultaneously dual-modal
imaging and synergetic PTT/RT to realize better anticancer efficiency
Indocyanine Green-Loaded Silver Nanoparticle@Polyaniline Core/Shell Theranostic Nanocomposites for Photoacoustic/Near-Infrared Fluorescence Imaging-Guided and Single-Light-Triggered Photothermal and Photodynamic Therapy
Photoacoustic
(PA)/near-infrared fluorescence (NIRF) dual-modal imaging-guided phototherapy
has been wide explored very recently. However, the development of
high-efficiency and simplified-performed theranostic system for amplifying
imaging-guided photothermal therapy/photodynamic therapy (PTT/PDT)
is still a great challenge. Herein, a single-light-triggered indocyanine
green (ICG)-loaded PEGylation silver nanoparticle core/polyaniline
shell (Ag@PANI) nanocomposites (ICG-Ag@PANI) for PA/NIRF imaging-guided
enhanced PTT/PDT synergistic effect has been successfully constructed.
In this study, the synthesized Ag@PANI nanocomposites are utilized
not only as the promising photothermal agent but also as potential
nanovehicles for loading photosensitizer ICG via π–π
stacking and hydrophobic interaction. The as-prepared ICG-Ag@PANI
possesses many superior properties such as strong optical absorption
in the near-infrared (NIR) region, enhanced photostability of ICG,
as well as outstanding NIR laser-induced local hyperthermia and reactive
oxygen species (ROS) generation. In the in vivo study, PA/NIRF dual-modal
imaging confirms the accumulation and distribution of ICG-Ag@PANI
in the tumor region via enhanced permeability and retention (EPR)
effect. Moreover, the PTT effect of ICG-Ag@PANI rapidly raised the
tumor temperature to 56.8 °C within 5 min. It is also demonstrated
that the cytotoxic ROS generation ability of ICG is well maintained
after being loaded onto Ag@PANI nanocomposites. Remarkably, in comparison
with PTT or PDT alone, the single 808 nm NIR laser-triggered combined
PTT/PDT therapy exhibits enhanced HeLa cells lethality in vitro and
tumor growth inhibition in vivo
Dual-Modal Imaging-Guided Theranostic Nanocarriers Based on Indocyanine Green and mTOR Inhibitor Rapamycin
The
development of treatment protocols that resulted in a complete
response to photothermal therapy (PTT) was usually hampered by uneven
heat distribution and low effectiveness. Here, we reported an NIR
fluorescence and photoacoustic dual-modal imaging-guided active targeted
thermal sensitive liposomes (TSLs) based on the photothermal therapy
agent Indocyanine green (ICG) and antiangiogenesis agent Rapamycin
(RAPA) to realize enhanced therapeutic and diagnostic functions. As
expected, the <i>in vitro</i> drug release studies exhibited
the satisfactory result of drug released from the TSLs under hyperthermia
conditions induced by NIR stimulation. The <i>in vitro</i> cellular studies confirmed that the FA-ICG/RAPA-TSLs plus NIR laser
exhibited efficient drug accumulation and cytotoxicity in tumor cells
and epithelial cells. After 24 h intravenous injection of FA-ICG/RAPA-TSLs,
the margins of tumor and normal tissue were accurately identified
via the <i>in vivo</i> NIR fluorescence and photoacoustic
dual-modal imaging. In addition, FA-ICG/RAPA-TSLs combined with NIR
irradiation treated tumor-bearing nude mice inhibited tumor growth
to a great extent and possessed much lower side effects to normal
organs. All detailed evidence suggested that the theranostic TSLs
which were capable of enhancing the therapeutic index might be a suitable
drug delivery system for dual-modal imaging-guided therapeutic tools
for diagnostics as well as the treatment of tumors