Magnet-targeted delivery of bone marrow-derived mesenchymal stem cells improves therapeutic efficacy following hypoxic-ischemic brain injury

hypoxicischemic brain injury;however,the therapeutic efficacy of bone marrow-derived mesenchymal stem cells largely depends on the number of cells that are successfully transferred to the target.Magnet-targeted drug delivery systems can use a specific magnetic field to attract the drug to the target site,increasing the drug concentration.In this study,we found that the double-labeling using superparamagnetic iron oxide nanoparticle and poly-L-lysine(SPIO-PLL)of bone marrow-derived mesenchymal stem cells had no effect on cell survival but decreased cell proliferation 48 hours after labeling.Rat models of hypoxic-ischemic brain injury were established by ligating the left common carotid artery.One day after modeling,intraventricular and caudal vein injections of 1×105 SPIO-PLL-labeled bone marrow-derived mesenchymal stem cells were performed.Twenty-four hours after the intraventricular injection,magnets were fixed to the left side of the rats’heads for 2 hours.Intravoxel incoherent motion magnetic resonance imaging revealed that the perfusion fraction and the diffusion coefficient of rat brain tissue were significantly increased in rats treated with SPIO-PLL-labeled cells through intraventricular injection combined with magnetic guidance,compared with those treated with SPIO-PLL-labeled cells through intraventricular or tail vein injections without magnetic guidance.Hematoxylin-eosin and terminal deoxynucleotidyl transferase dUTP nick-end labeling(TUNEL)staining revealed that in rats treated with SPIO-PLL-labeled cells through intraventricular injection under magnetic guidance,cerebral edema was alleviated,and apoptosis was decreased.These findings suggest that targeted magnetic guidance can be used to improve the therapeutic efficacy of bone marrow-derived mesenchymal stem cell transplantation for hypoxic-ischemic brain injury.This study was approved by the Animal Care and Use Committee of The Second Hospital of Dalian Medical University,China(approval No.2016-060)on March 2,2016.

Bonding strength of graded anti-corrosive coatings of fluoroethylenepropylene (FEP)/polyphenylene sulfide (PPS)

Fluororesin-based anti-corrosive coatings including graded FEP/PPS were prepared on carbon steel by melt powder coating, the bonding strength of all coating systems was determined by the pull-off test. It is found that the poor adhesion of fluororesin coatings to metallic substrates is improved obviously by the graded coating structure of FEP/PPS, and the bonding strength reaches up to 11.8 MPa for the five-layer system. Examination by electron probe microanalysis （EPMA） verifies that the distribution of main components is graded in the five-layer system, which is responsible for the enhancement of the interfacial bonding.

Comparison of Geotextiles by Aeration Vacuum Rapid Dewatering Technique on Dredged Sludge

In order to accelerate the consolidation of the dredged sludge and look for an effective material for mud-water separation,the study on the comparison of geotextiles is carried on. It is based on the laboratory model test of aeration vacuum rapid mud- water separating( AVMWS) technique and evaluated by the cumulative weight of pumping water,the decrease of moisture content and the stable pumping speed. The results show that woven fabric is the best anti- clogging aeration vacuum material,followed by machine-woven fabric and non-woven fabric is the worst. The analysis has been proposed from two aspects of geotextile weaving technology and aeration vacuum condition.

Polarization-dispersive imaging spectrometer for scattering circular dichroism spectroscopy of single chiral nanostructures

Circular dichroism spectroscopy is one of the most important tools in nanoscopic chiroptics.However,there is lack of simple,fast and reliable method for measuring the circular dichroism responses of single nanostructures.To tackle this issue,we report a polarization-dispersive imaging spectrometer which is capable of measuring the scattering circular dichroism response of a single chiral nanostructure with a single shot.Using this technique,we studied the scattering circular dichroism spectra of a model system,the vertically coupled plasmonic nanorod pair.Both experimental and theoretical results indicate that the polarization-dispersive spectrometer measures the imaginary part of nonlocal susceptibility of the structure.We further applied the technique to 3-dimensional Au nanorod structures assembled on DNA origami templates together with correlated scanning electron microscopic measurements.Rich chiroptical phenomena were unveiled at the single nanostructure level.

Revisiting Newton’s rings with a plasmonic optical flat for high-accuracy surface inspection

Two parallel optical surfaces often exhibit colorful fringes along the lines of equal thickness because of the interference of light.This simple phenomenon allows one to observe subwavelength corrugations on a reflective surface by simply placing on it a flat reference dielectric surface,a so-called optical flat,and inspecting the resultant interference pattern.In this work,we extend this principle from dielectric surfaces to two-dimensional plasmonic nanostructures.Optical couplings between an Au nanodisk array and an Au thin film were measured quantitatively using two different techniques,namely,the classical Newton’s rings method and a closed-loop nano-positioning system.Extremely high spectral sensitivity to the inter-surface distance was observed in the near-field coupling regime,where a 1-nm change in distance could alter the resonance wavelength by almost 10 nm,440 times greater than the variation in the case without near-field coupling.With the help of a numerical fitting technique,the resonance wavelength could be determined with a precision of 0.03 nm,corresponding to a distance precision as high as 0.003 nm.Utilizing this effect,we demonstrated that a plasmonic nanodisk array can be utilized as a plasmonic optical flat,with which nanometer-deep grooves can be directly visualized using a low-cost microscope.

细胞与活体内活性氧成像分析的有机荧光探针

活性氧(reactive oxygen species,ROS)是有氧代谢过程中形成的分子氧代谢物,参与细胞内多种生理和病理过程,与诸多疾病的发生发展密切相关.为研究ROS在相关生理病理事件中的作用,开发监测生物体内ROS的有效方法至关重要.基于探针的荧光成像技术因其高灵敏度和高时空分辨率而成为监测细胞和活体内生物活性分子的有力工具.本文从不同ROS有机荧光探针的构建出发,对近年来该类探针的研究进展进行了总结,重点对其设计思路、反应机理和生物应用进行了阐述.同时,也介绍了本课题组在该领域的研究成果.最后对未来挑战与发展方向进行了展望.

Construction and identification of lentiviral RNA interference vector of rat leptin receptor gene

Leptin resistance is a main mechanism of acquired childhood obesity,and the suppression of long form of leptin receptor(OBRb)gene expression in diet-induced obese rats indicates that the down-regulation of OBRb gene expression plays a pivotal role in the mechanism of leptin resistance.The aim of the present study was to construct the lentiviral RNA interference(RNAi)vector of rat OBRb gene and evaluate the effects of siRNA on silencing OBRb gene expression.The target sequence of siRNA-OBRb was designed,and the com-plementary DNA containing both sense and antisense oligonucleotides was synthesized.After phosphorylation and annealing,these double-stranded DNA was cloned to pRNA-lentivector-VGFP to construct pRNA-Lenti-OBRb-VGFP recombinants with U6-containing promoter,target sequence and Poly III terminator.Then,the products were confirmed by electrophoresis and sequencing analy-sis,and the effects of RNAi on reducing gene expression were further confirmed by real-time polymerase chain reaction in transfected rat glioma cells expressing OBRb.The target sequence of siRNA-OBRb was successfully cloned to pRNA-lentivector-VGFP,and the RNAi protocol specifically reduced the expression of OBRb mRNA by approximately 80%compared with controls in transfected rat glioma cells.The successful construction of rat lentivirus vectors expressing OBRb-specific shRNA may be useful for further investigation in vivo.