Optimization of surface enhanced Raman scattering performance based on Ag nanoparticle-modified vanadium-titanium nanorods with tunable nanogaps.

The combination of new noble metal nanomaterials and surface enhanced Raman scattering (SERS) technology has become a new strategy to solve the problem of low sensitivity in the detection of traditional Chinese medicine. In this work, taking natural cicada wing (C.w.) as a template, by optimizing the magnetron sputtering experimental parameters for the growth of Ag nanoparticles (NPs) on vanadium-titanium (V-Ti) nanorods, the nanogaps between the nanorods were effectively regulated and the Raman signal intensity of the Ag15/V-Ti20/C.w. substrate was improved. The proposed homogeneous nanostructure exhibited high SERS activity through the synergistic effect of the electromagnetic enhancement mechanism at the nanogaps between the Ag NPs modified V-Ti nanorods. The analytical enhancement factor (AEF) value was as high as 1.819 × 108, and the limit of detection (LOD) was 1 × 10-11 M for R6G. The large-scale distribution of regular electromagnetic enhancement "hot spots" ensured the good reproducibility with the relative standard deviation (RSD) value less than 7.31%. More importantly, the active compound of Artemisinin corresponded the pharmacological effect of Artemisia annua was screened out by SERS technology, and achieved a LOD of 0.01 mg/l. This reliable preparation technology was practically applicable to produce SERS-active substrates in detection of pharmacodynamic substance in traditional Chinese medicine.

KLF4 upregulation is involved in alternative macrophage activation during secondary Echinococcus granulosus infection.

The objective of this study was to investigate macrophage polarization during the early stages of secondary Echinococcus granulosus sensu lato (E. granulosus s.l.) infection. We observed an early initial increase in inflammatory genes (peaking at 5-10 days) and a later rise in M (IL-4)-like genes (still rising by day 15). In addition, we showed that the induction of M (IL-4)-like genes was paralleled by an increase in expression of the transcription factor KLF4. Most of the changes observed in vivo were reproduced in vitro upon the culture of normal peritoneal macrophages with live E. granulosus s.l. protoscoleces (PSC), and that knockdown of KLF4 in this system attenuates M (IL-4) differentiation. Our results suggest that KLF4 pathway contributes to the differentiation of macrophages towards M (IL-4)-like phenotype during early stages of secondary E. granulosus s.l. infection.

VEGF secreted by mesenchymal stem cells mediates the differentiation of endothelial progenitor cells into endothelial cells via paracrine mechanisms.

Stem cell therapy is a promising treatment strategy for ischemic diseases. Mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) adhere to each other in the bone marrow cavity and in in vitro cultures. We have previously demonstrated that the adhesion between MSCs and EPCs is critical for MSC self­renewal and their multi­differentiation into osteoblasts and chondrocytes. In the present study, the influence of the indirect communication between EPCs and MSCs on the endothelial differentiation potential of EPCs was investigated, and the molecular mechanisms underlying MSC­mediated EPC differentiation were explored. The effects of vascular endothelial growth factor (VEGF), which is secreted by MSCs, on EPC differentiation via paracrine mechanisms were examined via co­culturing MSCs and EPCs. Reverse transcription-quantitative polymerase chain reaction and western blot analysis were used to detect the expression of genes and proteins of interest. The present results demonstrated that co­culturing EPCs with MSCs enhanced the expression of cluster of differentiation 31 and von Willebrand factor, which are specific markers of an endothelial phenotype, thus indicating that MSCs may influence the endothelial differentiation of EPCs in vitro. VEGF appeared to be critical to this process. These findings are important for the understanding of the biological interactions between MSCs and EPCs, and for the development of applications of stem cell­based therapy in the treatment of ischemic diseases.