Ferrite-encapsulated nanoparticles with stable photothermal performance for multimodal imaging-guided atherosclerotic plaque neovascularization therapy.

Pathological angiogenesis is a critical contributor to atherosclerotic plaque rupture. However, there are few effective theranostic strategies to stabilize plaques by suppressing neovascularization. In this study, we fabricated a polymeric nanosystem using 3 nm manganese ferrite (MnFe2O4) and perfluorohexane (PFH) stabilized by polylactic acid-glycolic acid (PLGA) shells and conjugated to the surface of an anti-vascular endothelial growth factor receptor 2 (VEGFR2) antibody [ramucirumab (Ram)]. The PFH@PLGA/MnFe2O4-Ram nanoparticles (NPs) were used as atherosclerotic plaque angiogenesis theranostics for multimodal imaging-guided photothermal therapy (PTT). Three-nanometer MnFe2O4 is an excellent magnetic resonance imaging T1 and photoacoustic imaging contrast agent. Upon exposure to near-infrared (NIR) light, MnFe2O4 in the NPs could transform NIR light into thermal energy for the photothermal elimination of plaque angiogenesis. Additionally, optical droplet vaporization of PFH in the NPs triggered by the thermal effect to form gas bubbles enhanced ultrasound imaging. Our in vitro experiments revealed that PFH@PLGA/MnFe2O4-Ram NPs actively accumulated in rabbit aortic endothelial cells, and NP-mediated PTT promoted endothelial cell apoptosis while inhibiting their proliferation, migration, and tubulogenesis. Notably, the PFH@PLGA/MnFe2O4-Ram NPs possessed excellent photostability and biocompatibility. In the rabbit advanced atherosclerotic plaque model, PFH@PLGA/MnFe2O4-Ram NP-guided PTT significantly induced apoptosis of neovascular endothelial cells and improved the hypoxia status in the plaque 3 days after treatment. On day 28, PTT significantly reduced the density of neovessels and subsequently stabilized rabbit plaques by inhibiting plaque hemorrhage and macrophage infiltration. Collectively, these results suggest that PFH@PLGA/MnFe2O4-Ram NP-guided PTT is a safe and effective theranostic strategy for inhibiting atherosclerotic plaque angiogenesis.

A study of neuroprotective and antioxidant activities of heteropolysaccharides from six Sargassum species.

Heteropolysaccharides were extracted from Sargassum integerrimum (S.I), Sargassum maclurei (S.M), Sargassum naozhouense (S.N), Spiraea thunbergii (S.T), Sargassum hemiphyllum (S.H) and Sargassum fusiforme (S.F), and their neuroprotective effects and antioxidant activities were investigated. It showed that S.I, S.N, S.T and S.F exhibited neuroprotective activities, whereas S.H and S.M did not. For this reason, they were separated by anion-exchange chromatography. It was apparent that the fraction 2 represented the principal difference between the active and non-active compounds. However, it did not correlate with neuroprotective effect. In addition, the results on antioxidant activities showed that the hydroxyl-radical scavenging effect contribute to the neuroprotective effect of S.T and S.N, and the DPPH-radical scavenging effect and reducing power contribute to S.T, S.F and S.I. However, the superoxide-radical scavenging effect did not correlate with neuroprotective activity. The conclusion was that the neuroprotective activity of the family of compounds investigated depended on a variety of factors.