Although challenging, fabrication of porous conducting polymeric materials with excellent electronic properties is crucial for many applications. We developed a fast in situ polymerization approach to pure polyaniline (PANI) hydrogels, with vanadium pentoxide hydrate nanowires as both the oxidant and sacrifice template. A network comprised of ultrathin PANI nanofibers was generated during the in situ polymerization, and the large aspect ratio of these PANI nanofibers allowed the formation of hydrogels at a low solid content of 1.03 wt %. Owing to the ultrathin fibril structure, PANI hydrogels functioning as a supercapacitor electrode display a high specific capacitance of 636 F g, a rate capability, and good cycling stability (∼83% capacitance retention after 10,000 cycles). This method was also extended to the preparation of polypyrrole and poly(3,4-ethylenedioxythiophene) hydrogels. This template polymerization method represents a rational strategy for design of conducing polymer networks, which can be readily integrated in high-performance devices or a further platform for functional composites.
Ferroptosis,
a promising mechanism of killing cancer cells, has
become a research hotspot in cancer therapy. Besides, advantages of
polymeric nanomaterials in improving anticancer efficacy and reducing
side effect are widely accepted. In this work, based on the property
of polypodamine to chelate metal ions, ultrasmall poly(ethylene glycol)-modified
polydopamine nanoparticles, (UPDA-PEG)@Fe2+/3+ nanoparticles,
a novel ferroptosis agent, was rationally designed by chelating iron
ions on ultrasmall polydopamine nanoparticles modified by PEG. This
treatment led to a bigger specific surface area, which could support
more reactive sites to chelate large number of iron ions, which is
beneficial for exploring the detailed mechanism of ferroptosis-induced
tumor cell death by iron ions. Also, the pH-dependent release of iron
ions can reach approximately 70% at pH 5.0, providing the advantage
of application in tumor microenvironment. The in vitro tests showed
that the as-prepared NPs exhibit an effective anticancer effect on
tumor cells including 4T1 and U87MG cells, yet ferric ions show a
stronger ability of killing cancer cells than ferrous ions. Differences
between ferrous ions and ferric ions in the ferroptosis pathway were
monitored by the change of marker, including reactive oxygen species
(ROS), glutathione peroxidase 4, and lipid peroxide (LPO), as well
as the promoter and inhibitor of ferroptosis pathway. UPDA-PEG@Fe2+ nanoparticles induce ferroptosis that depends more on ROS;
however, a more LPO-dependent ferroptosis is induced by UPDA-PEG@Fe3+ nanoparticles. Additionally, the in vivo studies using tumor-bearing
Balb/c mice demonstrated that the as-prepared NPs could significantly
inhibit tumor progression. UPDA-PEG@Fe2+/3+ nanoparticles
reported herein represent the nanoparticles related to iron ions for
chemotherapy against cancer through the ferroptosis pathway.
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