Determination of six arsenic species in human urine by HPLC-ICP-MS

ObjectiveTo establish an High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry （HPLC-ICP-MS） method for determination of six arsenic species in human urine，including arseniccholine （AsC）， arsenobetaine （AsB）， arsenite （As3+）， dimethylarsinic acid （DMA5+）， monomethylarsonic acid （MMA5+）， and arsenate （As5+）.MethodsThe pH value of mobile phase and the content of anhydrous ethanol were optimized. Ammonium carbonate （50 mmol·L-1， containing 2% anhydrous ethanol， pH-8.5） mobile phase was selected. Cl- interference was eliminated by He mode. The arsenic species in 10-fold diluted human urine samples were separated by an Hamilton PRP X-100 anionic column. A method for the determination of six arsenic species was established.ResultsSix arsenic species could be separated in 13 minutes. The linear correlation coefficients were above 0.999. The limits of detection were 0.10‒0.20 μg·L-1， and the limits of quantification were 0.30‒0.50 μg·L-1. Precision experiments showed that RSD ranged from 5.96% to 9.07% when adding concentration 0.20 μg·L-1； from 2.48% to 6.38% when adding concentration 2.00 μg·L-1； and from 1.41% to 2.57% when adding concentration 5.00 μg·L-1. Accuracy test showed that the recoveries were 80%‒125%.ConclusionThe established HPLC-ICP-MS method for determination of six arsenic species in human urine is rapid， accurate and sensitive. It can be applied to the determination of arsenic species in human urine

Effects of Carboxylated Multiwalled Carbon Nanotubes on the Function of Macrophages

Multiwalled carbon nanotubes (MWCNTs) have tremendous potential in many areas of research and applications. Modification of MWCNTs with carboxyl group is one of the widely used strategies to increase their water dispersibility. However, the effect of carboxylation of MWCNTs on their interaction with macrophages remains unclear. The current study compared the impact of pristine MWCNTs (p-MWCNTs) and carboxylic acid functionalized MWCNTs (MWCNTs-COOH) on RAW264.7 cells by looking at the cell viability, phagocytic activity, production of cytokines (IL-1β, IL-10, IL-12, and TNF-α), and intracellular reactive oxygen species (ROS). It was revealed that exposure to either p-MWCNTs or MWCNTs-COOH induced decreased viability of murine macrophage RAW 264.7 cells and moderately elevated phagocytic activity of murine peritoneal macrophages, but no statistical significance was found between the two groups. Increased production of ROS in macrophages was induced after exposure to either p-MWCNTs or MWCNTs-COOH. However, no significantly elevated production of cytokines (IL-1β, IL-10, IL-12, and TNF-α) was observed from RAW 264.7 cells after exposure to the CNTs. Those data suggested that modification with carboxyl group did not exert obvious impact on the interaction of MWCNTs with macrophages

A cell-penetrating peptide-assisted nanovaccine promotes antigen cross-presentation and anti-tumor immune response

Exogenous antigens processed in the cytosol and subsequently cross-presented on major histocompatibility complex class I (MHC-I) molecules activate cytotoxic CD8 lymphocytes (CTL), which are crucial in cancer immunotherapy. Here, we reported a nanovaccine, which was produced by encapsulating OVA (ovalbumin, a model antigen) chemically modified with MPG (MPG-OVA conjugate) into poly(lactide-co-glycolide) acid (PLGA) nanoparticles. We hypothesized that after the uptake of the nanovaccine into immune cells, MPG, a cell-penetrating peptide (CPP), would assist the escape of the antigens from lysosomes into the cytosol, increase the amount of antigens processed in the cytosol and subsequently enhance antigen cross-presentation via MHC-I molecules to elicit cytotoxic CD8 T cell responses. The results of the in vitro experiments demonstrated that the MPG-OVA-loaded PLGA NPs not only elevated the release of OVA into the cytosol of dendritic cells (BMDCs), but also promoted the maturation and activation of BMDCs. It was also observed in mice vaccinated with MPG-OVA-loaded PLGA NPs that the MPG modification could stimulate the expansion of OVA-specific T-cells, generation of OVA-specific IgG antibodies and proliferation of OVA-specific memory T cells. Moreover, the treatment of E·G7-OVA tumor-bearing mice with MPG-OVA-loaded PLGA NPs resulted in significantly suppressed tumor growth and prolonged survival periods of the mice compared to the treatment with unmodified OVA-PLGA NPs or free OVA. In summary, cell-penetrating peptides linked with antigens encapsulated in nanovaccines can spatiotemporally affect the intracellular localization of antigens, promote antigen cross-presentation and stimulate antigen-specific immune responses, especially CTL responses. Therefore, the CPP modification on antigens is an innovative approach to enhance the efficacy of nanovaccines for cancer immunotherapy

The yeast protein Ure2p triggers Tau pathology in a mouse model of tauopathy

Summary: The molecular mechanisms that trigger Tau aggregation in Alzheimer’s disease (AD) remain elusive. Fungi, especially Saccharomyces cerevisiae (S. cerevisiae), can be found in brain samples from patients with AD. Here, we show that the yeast protein Ure2p from S. cerevisiae interacts with Tau and facilitates its aggregation. The Ure2p-seeded Tau fibrils are more potent in seeding Tau and causing neurotoxicity in vitro. When injected into the hippocampus of Tau P301S transgenic mice, the Ure2p-seeded Tau fibrils show enhanced seeding activity compared with pure Tau fibrils. Strikingly, intracranial injection of Ure2p fibrils promotes the aggregation of Tau and cognitive impairment in Tau P301S mice. Furthermore, intranasal infection of S. cerevisiae in the nasal cavity of Tau P301S mice accelerates the aggregation of Tau. Together, these observations indicate that the yeast protein Ure2p initiates Tau pathology. Our results provide a conceptual advance that non-mammalian prions may cross-seed mammalian prion-like proteins

Simultaneous monitoring of the drug release and antitumor effect of a novel drug delivery system-MWCNTs/DOX/TC

Monitoring drug release and therapeutic efficacy is crucial for developing drug delivery systems. Our preliminary study demonstrated that, as compared with pristine multiwalled carbon nanotubes (MWCNTs), transactivator of transcription (TAT)-chitosan functionalized MWCNTs (MWCNTs-TC) were a more promising candidate for drug delivery in cancer therapy. In the present study, a MWCNTs/TC-based drug delivery system was developed for an anticancer drug, doxorubicin (DOX). The drug loading and in vitro release profiles, cellular uptake and cytotoxicity were assessed. More importantly, the in vivo drug release and antitumor effect of MWCNTs/DOX/TC were evaluated by noninvasive fluorescence and bioluminescence imaging. It was demonstrated that MWCNTs/DOX/TC can be efficiently taken up by BEL-7402 hepatoma cells. The release of DOX from MWCNTs/DOX/TC was faster under lower pH condition, which was beneficial for intrcellular drug release. The in vivo release process of DOX and antitumor effect in animal model were monitored simultaneously by noninvasive fluorescence and luminescence imaging, which demonstrated the application potential of MWCNTs/DOX/TC for cancer therapy

Energy Storage Properties of Sol–Gel-Processed SrTiO₃ Films

Dielectric films with a high energy storage density and a large breakdown strength are promising material candidates for pulsed power electrical and electronic applications. Perovskite-type dielectric SrTiO3 (STO) has demonstrated interesting properties desirable for capacitive energy storage, including a high dielectric constant, a wide bandgap and a size-induced paraelectric-to-ferroelectric transition. To pave a way toward large-scale production, STO film capacitors were deposited on Pt(111)/Ti/SiO2/Si(100) substrates by the sol–gel method in this paper, and their electrical properties including the energy storage performance were studied as a function of the annealing temperature in the postgrowth rapid thermal annealing (RTA) process. The appearance of a ferroelectric phase at a high annealing temperature of 750 °C was revealed by X-ray diffraction and electrical characterizations (ferroelectric P-E loop). However, this high dielectric constant phase came at the cost of a low breakdown strength and a large hysteresis loss, which are not desirable for the energy storage application. On the other hand, when the RTA process was performed at a low temperature of 550 °C, a poorly crystallized perovskite phase together with a substantial amount of impurity phases appeared, resulting in a low breakdown strength as well as a very low dielectric constant. It is revealed that the best energy storage performance, which corresponds to a large breakdown strength and a medium dielectric constant, is achieved in STO films annealed at 650 °C, which showed a large energy density of 55 J/cm3 and an outstanding energy efficiency of 94.7% (@ 6.5 MV/cm). These findings lay out the foundation for processing high-quality STO film capacitors via the manufacturing-friendly sol–gel method