Chemical Research in Chinese Universities

Stent graft(SG), isolating the diseased vessels from the normal blood circulation and preventing the rupture of the aneurysm wall in minimally invasive surgery, is normally composed of a metallic stent and a cover with a textile structure. In this study, the electrospinning method was used to prepare a new type of cover, and the preparing conditions and the performance of the SG were investigated. The polytetrafluoroethylene(PTFE) and polyethylene oxide(PEO) were blended at the ratios of 99:1, 98:2, 97:3 and electrospun to form precursor membranes. Then they were dried in a vacuum and sintered at different temperatures under different time periods to obtain PTFE membrane, which was compounded with a stent. Their morphology, mechanical properties, water permeability and biological properties were studied. The results showed that when the membrane was sintered at 380 °C for 10 min, it had the best tensile properties. The integral water permeability of the PTFE electrospun SG was close to 0. The hemolysis rate of the SG was 2.84%, and human umbillical vein endothelial cells(HUVECs) can adhere and proliferate well on the surface of the PTFE membranes. The PTFE electrospun SG had great potential for clinical application and industrialization.

For the efficient extraction of kamebakaurin(KA), the ultrasound-assisted extraction(UAE) of KA from Rabdosia excisa(R. excisa) via response surface methodology(RSM) was investigated with high-performance liquid chromatography(HPLC). Effects of the experimental parameters such as extraction solvent, ratio of liquid to plant material, extraction time and extraction temperature on the extracting efficiency of KA from R. excisa were evaluated, and the purity of KA in residual was calculated. The optimized conditions were 65.5%(volume fraction) acetone, 35 °C, time of 24.6 min with ultrasound of 80 W/L, 40 kHz, ratio of liquid to plant material at 30:1(mL/g). The maximum yield of KA is 0.708 mg/kg, with mean purity of 6.09%, indicating that ultrasound-assisted extraction is a feasible and useful method for extracting KA from R. excisa.

A series of novel 5-alkoxyfuran-2(5H)-one derivatives was synthesized, and characterized by 1H NMR, 13C NMR and HRMS. Biological activities of all the title compounds were evaluated systematically. Preliminary bioassays indicated that most of the compounds exhibited moderate insecticidal activities against Aphis craccivora and Nilaparvata lugens at 100 mg/L. Compounds 4h and 4w exhibited 100% mortality rate against Aphis craccivora at 100 mg/L, and compound h exhibited good mortality rate against Aphis craccivora and Nilaparvata lugens (60% and 75%, respectively) even at 4 mg/L. The results demonstrated the impact of various chemical groups on insecticidal activities and provided a potential clue for further exploring novel high-effective broad-spectrum insecticides.

Chlorinated paraffins(CPs) are potential persistent organic pollutants(POPs), which threat the safety of environment and organisms. However, the analysis of CPs is a difficult task due to their complex composition containing thousands of congeners. In the present work, quantitative structure retention relationship(QSRR) of CPs was studied. A total of 470 molecular descriptors were generated, for describing the structures of 28 CPs and 12 descriptors relevant to retention time of the CPs were selected by stepwise regression. Then, QSRR models between retention time on the one hand and the selected descriptors on the other hand were established by multiple linear regression(MLR), partial least squares(PLS) and least square support vector regression(LS-SVR). The result shows that PLS model is better than MLR and LS-SVR, obtaining a squared correlation coefficient(r 2) of 0.9996 and a root mean squared error(RMSE) of 0.015. The PLS model was then used to predict the retention time of 49 C10-CPs. Three of them were investigated by gas chromatography coupled with mass spectrometry(GC-MS). A well-defined correlation was found between the measured retention time and the predicted value.

We established a novel strategy for the synthesis of reduced graphene oxide(rGO)@TiO2 nanotube hybrids using an 18 W UV-assisted photo-catalytic reduction method for utilization as photo-anode of dye-sensitized solar cells(DSSCs). The photo-conversion efficiency of DSSCs was significantly enhanced after the addition of rGO, and in addition, the photo-anode showed decreased internal resistance. Analysis of rGO@TiO2 hybrids by transmissions scanning electron microscopy(TEM), X-ray diffraction(XRD), Raman spectra, N2 adsorption and desorption, atomic force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS) demonstrates that the rGO modified TiO2 nanotubes can increase the short-circuit current and the conversion efficiency of dye-sensitized solar cells. The efficiency is improved by almost two folds as much compared to those of the bare TiO2 nanotubes.

Bio-template method has recently attracted much attention because of its prominent advantages in obtaining morphology controlled materials with structural specificity, complexity and their unique functions. The bio-template method combining with electrochemical deposition was employed to synthesize spirulina/hematite composite microstructures using native spirulina as template. A great amount of hematite(α-Fe2O3) nanoparticles can be formed and deposited onto the spirulina, resulting in a robust and pseudo-homogeneous surface. And the spirulina/α-Fe2O3 composite exhibits an improved surface wettability due to its helical morphology. This facile strategy may open new horizons in the field of replicating specific biological structures for functional materials in other potential applications.

Electrospun nanofibers are of the same length scale as the native extracellular matrix and have been extensively reported to facilitate adhesion and proliferation of cells and to promote tissue repair and regeneration. With a primary focus on tissue repair and regeneration using electrospun scaffolds, only a few studies involved electrospun nanofiber scaffolds directing cell behaviors have been reported. In this study, we prepared electrospun nanofiber scaffolds with distinct fiber configurations, namely, random and aligned orientations of nanofibers, as well as oriented yarns, and investigated their effects on cell behaviors. Our results showed that these scaffolds supported good proliferation and viability of murine fibroblasts. Fiber configuration profoundly influenced cell morphology and orientation but showed no effects on cell proliferation rate. The yarn scaffold had comparable total protein accumulation with the random and aligned scaffolds, but it supported a greater proliferation rate of fibroblasts with significantly elevated collagen deposition due to its porous fibrous configuration. Cell-seeded yarn scaffolds showed a greater Young’s modulus compared with cell-free controls as early as 1 week. Together with its unique fiber configuration similar to the native extracellular matrix of the myocardium, the yarn scaffold might be a suitable matrix material for modeling cardiac fibrotic disorders.

Cr2O3@ZnO hetero-junction hierarchical nanostructures were designed to be enhanced xylene sensing material, and thereinto, flower-like ZnO hierarchical nanostructures were synthesized via a solution-based method, and then Cr2O3 particles were developed on the surface of ZnO petals via a solvothermal method. From the results of XRD patterns, SEM and TEM images, it can be observed that ZnO has a high-quallity crystallinity and Cr2O3 particles scatter uniformly on the suruface of ZnO. The products with different ratios of Cr2O3 were used to fabricate gas sensors, and the result indicates that the hetero-junction structures prompt the response to xylene, and the reason may be attributed to the decrease of main carriers concentration caused by the p-n junction between ZnO(n-type semiconductor) and Cr2O3(p-type semiconductor), as well as the catalytic oxidation effect on methyl groups of the xylene by Cr2O3.

Fluorescence imaging in the second near-infrared window(NIR-II, 1000―1700 nm) has demonstrated tremendous promise for biomedical applications, with its extraordinarily high resolution and deep tissue penetration. Ultrasmall gold nanoclusters(AuNCs) have shown unique features for NIR-II imaging, such as photostability and biocompatibility, as compared to organic NIR-II molecules or other inorganic NIR-II nanoparticles. Here, we report the first-in-class protein-capped ultrasmall AuNCs(BSA-AuNCs, BSA=bovine serum albumin) for simultaneous NIR-II imaging and photodynamic therapy. The BSA-AuNCs show a uniform size, high quantum yield and excellent photostability, display a high accumulation and long retention in 4T1 tumor, and are used for clear imaging of blood vessels and lymph nodes. Moreover, laser irradiation of these AuNCs can rapidly trigger ROS generation, leading to effective inhibition of tumor cell growth in vitro and in vivo. This study demonstrates the feasibility of a protein-capped ultrasmall AuNCs platform for theranostic applications by combining NIR-II imaging and photodynamic cancer therapy.