3 research outputs found
Redox Potential-Sensitive <i>N</i>‑Acetyl Cysteine-Prodrug Nanoparticles Inhibit the Activation of Microglia and Improve Neuronal Survival
One hallmark of neuroinflammation
is the activation of microglia,
which triggers the production and release of reactive oxygen species
(ROS), nitrate, nitrite, and cytokines. <i>N</i>-Acetyl
cysteine (NAC) is a free radical scavenger that is involved in the
intracellular and extracellular detoxification of reactive oxygen
species in the brain. However, the clinical application of NAC is
limited by its low bioavailability and short half-life. Herein, NAC
was conjugated to a polymer through a disulfide bond to form a NAC-prodrug
nanoparticle (NAC-NP). Dynamic light scattering found that the NAC-NP
has a size of around 50 nm. In vitro studies revealed that the release
of NAC from NAC-NP is responsive to its environmental redox potential.
For mimicking neuroinflammation in vitro, microglial cells were stimulated
by a lipopolysaccharide (LPS), and the effect of NAC-NP on activated
microglia was investigated. The study found that the morphology as
well as the expression of microgliosis marker Iba-1 of the cells treated
with NAC-NPs and LPS were close to those of control cells, indicating
that NAC-NPs can inhibit the activation of microglia stimulated by
LPS. Compared with free NAC, the production of ROS, NO<sub>3</sub>-, NO<sub>2</sub>-, tumor necrosis factor-α (TNF-α),
and interleukin (IL)-1β from the LPS-stimulated microglia was
considerably decreased when the cells were pretreated with NAC-NPs.
Furthermore, LPS-induced microglial phagocytocis of neurons was inhibited
in the presence of NAC-NPs. These results indicated that NAC-NPs are
more effective than free NAC for reversing the effect of LPS on microglia
and subsequently protecting neurons
pH and Redox Dual Responsive Nanoparticle for Nuclear Targeted Drug Delivery
To mimic the clinic dosing pattern, initially administering
high
loading dose and then low maintenance dose, we designed a novel poly(2-(pyridin-2-yldisulfanyl)ethyl
acrylate) (PDS) based nanoparticle delivery system. Side chain functional
PDS was synthesized by free radical polymerization. Polyethylene glycol
and cyclo(Arg-Gly-Asp-d-Phe-Cys) (cRGD) peptide was conjugated
to PDS through thiol–disulfide exchange reaction to achieve
RPDSG polymer. RPDSG/DOX, RPDSG nanoparticle loaded with doxorubicin,
was fabricated by cosolvent dialysis method. The size of the nanoparticles
was 50.13 ± 0.5 nm in PBS. The RPDSG/DOX nanoparticle is stable
in physiological condition while quickly releasing doxorubicin with
the trigger of acidic pH and redox potential. Furthermore, it shows
a two-phase release kinetics, providing both loading dose and maintenance
dose for cancer therapy. The conjugation of RGD peptide enhanced the
cellular uptake and nuclear localization of the RPDSG/DOX nanoparticles.
RPDSG/DOX exhibits IC<sub>50</sub> close to that of free doxorubicin
for HCT-116 colon cancer cells. Due to the synergetic effect of RGD
targeting effect and its two-phase release kinetics, RPDSG/DOX nanoparticles
display significantly higher anticancer efficacy than that of free
DOX at concentrations higher than 5 μM. These results suggest
that RPDSG/DOX could be a promising nanotherapeutic for tumor-targeted
chemotherapy
Redox Potential Ultrasensitive Nanoparticle for the Targeted Delivery of Camptothecin to HER2-Positive Cancer Cells
Ideal
“smart” nanoparticles for drug delivery should
enhance therapeutic efficacy without introducing side effects. To
achieve that, we developed a drug delivery system (HCN) based on a
polymer–drug conjugate of poly[2-(pyridin-2-yldisulfanyl)]-<i>graft</i>-poly(ethylene glycol) and camptothecin with an intracellularly
cleavable linker and human epidermal growth factor receptor 2 (HER2)
targeting ligands. An <i>in vitro</i> drug release study
found that HCN was stable in the physiological environment and supersensitive
to the stimulus of elevated intracellular redox potential, releasing
all payloads in less than 30 min. Furthermore, confocal microscopy
revealed that HCN could specifically enter HER2-positive cancer cells.
As a consequence, HCN could effectively kill HER2-positive cancer
cells while not affecting HER2-negative cells