4 research outputs found
Ultrasmall-Superbright Neodymium-Upconversion Nanoparticles via Energy Migration Manipulation and Lattice Modification: 808 nm-Activated Drug Release
Nd<sup>3+</sup>-sensitized
upconversion nanoparticles are among
the most promising emerging fluorescent nanotransducers. They are
activated by 808 nm irradiation, which features merits such as limited
tissue overheating and deeper penetration depth, and hence are attractive
for diagnostic and therapeutic applications. Recent studies indicate
that ultrasmall nanoparticles (<10 nm) are potentially more suitable
for clinical application due to their favorable biodistribution and
safety profiles. However, upconversion nanoparticles in the sub-10
nm range suffer from poor luminescence due to their ultrasmall size
and greater proportion of lattice defects. To reconcile these opposing
traits, we adopt a combinatorial strategy of energy migration manipulation
and crystal lattice modification, creating ultrasmall-superbright
Nd<sup>3+</sup>-sensitized nanoparticles with 2 orders of magnitude
enhancement in upconversion luminescence. Specifically, we configure
a sandwich-type nanostructure with a Yb<sup>3+</sup>-enriched intermediate
layer [Nd<sup>3+</sup>]–[Yb<sup>3+</sup>–Yb<sup>3+</sup>]–[Yb<sup>3+</sup>–Tm<sup>3+</sup>] to form a positively
reinforced energy migration system, while introducing Ca<sup>2+</sup> into the crystal lattice to reduce lattice defects. Furthermore,
we apply the nanoparticles to 808 nm light-mediated drug release.
The results indicate time-dependent cancer cells killing and better
antitumor activities. These ultrasmall-superbright dots have unraveled
more opportunities in upconversion photomedicine with the promise
of potentially safer and more effective therapy
Redox-Sensitive Hydroxyethyl Starch–Doxorubicin Conjugate for Tumor Targeted Drug Delivery
Doxorubicin (DOX)
is one of the most potent anticancer agents in cancer chemotherapy,
but the clinical use of DOX is restricted by its severe side effects
caused by nonspecific delivery. To alleviate the side effects and
improve the antitumor efficacy of DOX, a novel redox-sensitive hydroxyethyl
starch–doxorubicin conjugate, HES-SS-DOX, with diameter of
19.9 ± 0.4 nm was successfully prepared for tumor targeted drug
delivery and GSH-mediated intracellular drug release. HES-SS-DOX was
relatively stable under extracellular GSH level (∼2 μM)
but released DOX quickly under intracellular GSH level (2–10
mM). In vitro cell study confirmed the GSH-mediated cytotoxicity of
HES-SS-DOX. HES-SS-DOX exhibited prolonged plasma half-life time and
enhanced tumor accumulation in comparison to free DOX. As a consequence,
HES-SS-DOX exhibited better antitumor efficacy and reduced toxicity
as compared to free DOX in the in vivo antitumor activity study. The
redox-sensitive HES-SS-DOX was proved to be a promising prodrug of
DOX, with clinical potentials, to achieve tumor targeted drug delivery
and timely intracellular drug release for effective and safe cancer
chemotherapy
α‑Amylase- and Redox-Responsive Nanoparticles for Tumor-Targeted Drug Delivery
Paclitaxel (PTX)
is an effective antineoplastic agent and shows potent antitumor activity
against a wide spectrum of cancers. Yet, the wide clinical use of
PTX is limited by its poor aqueous solubility and the side effects
associated with its current therapeutic formulation. To tackle these
obstacles, we report, for the first time, α-amylase- and redox-responsive
nanoparticles based on hydroxyethyl starch (HES) for the tumor-targeted
delivery of PTX. PTX is conjugated onto HES by a redox-sensitive disulfide
bond to form HES–SS-PTX, which was confirmed by results from
NMR, high-performance liquid chromatography-mass spectrometry, and
Fourier transform infrared spectrometry. The HES–SS-PTX conjugates
assemble into stable and monodispersed nanoparticles (NPs), as characterized
with Dynamic light scattering, transmission electron microscopy, and
atomic force microscopy. In blood, α-amylase will degrade the
HES shell and thus decrease the size of the HES–SS-PTX NPs,
facilitating NP extravasation and penetration into the tumor. A pharmacokinetic
study demonstrated that the HES–SS-PTX NPs have a longer half-life
than that of the commercial PTX formulation (Taxol). As a consequence,
HES–SS-PTX NPs accumulate more in the tumor compared with the
extent of Taxol, as shown in an in vivo imaging study. Under reductive
conditions, the HES–SS-PTX NPs could disassemble quickly as
evidenced by their triggered collapse, burst drug release, and enhanced
cytotoxicity against 4T1 tumor cells in the presence of a reducing
agent. Collectively, the HES–SS-PTX NPs show improved in vivo
antitumor efficacy (63.6 vs 52.4%) and reduced toxicity in 4T1 tumor-bearing
mice compared with those of Taxol. These results highlight the advantages
of HES-based α-amylase- and redox-responsive NPs, showing their
great clinical translation potential for cancer chemotherapy
Synergizing Upconversion Nanophotosensitizers with Hyperbaric Oxygen to Remodel the Extracellular Matrix for Enhanced Photodynamic Cancer Therapy
Photodynamic
therapy (PDT) holds great promise as a noninvasive and selective cancer
therapeutic treatment in preclinical research and clinical practice;
however, it has limited efficacy in the ablation of deep-seated tumor
because of hypoxia-associated circumstance and poor penetration of
photosensitizers to cancer cells away from the blood vessels. To tackle
the obstacles, we propose a therapeutic strategy that synergizes upconversion
nanophotosensitizers (UNPSs) with hyperbaric oxygen (HBO) to remodel
the extracellular matrix for enhanced photodynamic cancer therapy.
The UNPSs are designed to have an Nd<sup>3+</sup>-sensitized sandwiched
structure, wherein the upconversion core serves as light transducers
to transfer energy to the neighboring photosensitizers to produce
reactive oxygen species (ROS). With HBO, photodynamic process can
generate abundant ROS in the intrinsically hypoxic tumor. It is revealed
for the first time that HBO-assisted PDT decomposes collagen in the
extracellular matrix of tumor and thus facilitates the diffusion of
oxygen and penetration of UNPSs into the deeper area of tumor. Such
a synergic effect eventually results in a significantly enhanced therapeutic
efficacy at a low laser power density as compared with that using
UNPSs alone. In view of its good biosafety, the HBO-assisted and UNPSs-mediated
PDT provides new possibilities for treatment of solid tumors