Helicoidal Patterning of Gold Nanorods by Phase Separation in Mixed Polymer Brushes.

The spatial distribution of polymer ligands on the surface of nanoparticles (NPs) is of great importance because it determines their interactions with each other and with the surrounding environment. Phase separation in mixtures of polymer brushes has been studied for spherical NPs; however, the role of local surface curvature of nonspherical NPs in the surface phase separation of end-grafted polymer ligands remains an open question. Here, we examined phase separation in mixed monolayers of incompatible polystyrene and poly(ethylene glycol) brushes end-capping the surface of gold nanorods in a good solvent. By varying the molar ratio between these polymers, we generated a range of surface patterns, including uniform and nonuniform polystyrene shells, randomly distributed polystyrene surface patches, and, most interestingly, a helicoidal pattern of polystyrene patches wrapping around the nanorods. The helicoidally patterned nanorods exhibited long-term colloidal stability in a good solvent. The helicoidal wrapping of the nanorods was achieved for the mixtures of polymers with different molecular weights and preserved when the quality of the solvent for the polymers was reduced. The helicoidal organization of polymer patches on the surface of nanorods can be used for templating the synthesis or self-assembly of helicoidal multicomponent nanomaterials.

Directing Assembly and Disassembly of 2D MoS2 Nanosheets with DNA for Drug Delivery.

Layer-by-layer (LbL) self-assembled stacked Testudo-like MoS2 superstructures carrying cancer drugs are formed from nanosheets controllably assembled with sequence-based DNA oligonucleotides. These superstructures can disassemble autonomously in response to cancer cells' heightened ATP metabolism. First, we functionalize MoS2 nanosheets (MoS2-NS) nanostructures with DNA oligonucleotides having thiol-terminated groups (DNA/MoS2-NS) via strong binding to sulfur atom defect vacancies on MoS2 surfaces. The driving force to assemble into a higher-order DNA/MoS2-NS superstructure is guided by a linker aptamer that induced interlayer assembly. In the presence of target ATP molecules, these multilayer superstructures disassembled as a consequence of stronger binding of ATP molecules with the linking aptamers. This design plays a dual role of protection and delivery by LbL stacked MoS2-NS similar in concept to a Greek Testudo. These superstructures present a protective armor-like shell of MoS2-NS, which still remains responsive to small and infiltrating ATP molecules diffusing through the protective MoS2-NS, contributing to an enhanced stimuli-responsive drug release system for targeted chemotherapy.

Inhibition on hepatitis B virus in vitro of lectin from Musca domestica pupa via the activation of NF-κB.

The present study reported that the secretions of HBsAg and HBeAg in HepG2.2.15 cells were significantly decreased under the treatment of lectin from Musca domestica pupa (MPL). Both the replication of hepatitis B virus (HBV) DNA and HBV cccDNA in cells, and the copies of extracellular HBV DNA were inhibited by MPL. The mRNA expressions of interleukin-2 (IL-2), gamma interferon (INF-γ) and MxA were up-regulated by MPL treatments, but down-regulated when nuclear factor-κB (NF-κB) signal pathway was blocked by pyrrolidine dithiocarbamate (PDTC). Subsequent investigation revealed that nuclear factor-κB inhibitory κB (IκB) in endochylema was inhibited and NF-κB was translocated into the nucleus. These findings indicate that MPL could inhibit HBV replication via the induction of the expression of IL-2, INF-γ and MxA through the activation of NF-κB.

Musca domestica pupae lectin improves the immunomodulatory activity of macrophages by activating nuclear factor-κB.

In this study, Musca domestica pupae lectin (MPL) was screened for its immunomodulatory effect on macrophages. The phagocytosis of macrophages was improved significantly when they were treated with MPL: remarkable changes were observed in the morphology of the cells, the metabolic abilities of DNA and RNA were enhanced, and the production of hepatin was increased. Meanwhile, compared with the control group, not only the mRNA expressions of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interferon-γ (IFN-γ) in macrophages, but also the productions of proteins, were strongly induced by MPL; these effects were inhibited by pyrrolidine dithiocarbamate. Further study suggested that MPL could increase the nuclear factor-κB (NF-κB) p65 level in the nucleus. Overall, these results indicate that the improving immunomodulatory activity induced by MPL is mainly due to the increasing productions of TNF-α, IL-6, and IFN-γ and that the activation of macrophage by MPL is partly mediated via the NF-κB pathway.