Yeungnam University

About: Yeungnam University is a education organization based out in Daegu, South Korea. It is known for research contribution in the topics: Thin film & Catalysis. The organization has 9885 authors who have published 22075 publications receiving 372798 citations.

Concurrent synthesis of nitrogen-doped carbon dots for cell imaging and ZnO@nitrogen-doped carbon sheets for photocatalytic degradation of methylene blue

Abstract: The hybrid composite of ZnO nanoparticles decorated nitrogen-doped graphitic carbon sheets (ZnO@N-C) alongside nitrogen-doped carbon dots (N-CDs) were synthesized by the direct hydrothermal method of peach fruit juice and ZnO nanoparticles (ZnO NPs). The synthesized ZnO@N-C hybrid composite and N-CDs were thoroughly characterized by various physicochemical techniques including powder X-ray diffraction (PXRD), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) with energy-dispersive X-ray (EDX) spectroscopy, high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, and fluorescence spectroscopy. The ZnO NPs were dispersed in the graphitic carbon structure with an average size of 25 ± 5 nm. The chemical composition of C, O, N, and Zn within the ZnO@N-C hybrid composite exhibits enough graphitization. Methylene blue (MB)-degradation was estimated utilizing the ZnO@N-C hybrid composite, a maximum degradation efficiency of >95% was achieved in a neutral aqueous medium within 60 min under UV-light irradiation. This maximum efficiency allows estimating the contribution of the heterogeneous and homogeneity of ZnO@N-C hybrid composite which is responsible for the MB-degradation. Moreover, the economic natural biosource or bio-waste was employed for the synthesis of ZnO@N-C hybrid composite and displays an excellent photocatalytic degradation under UV-light irradiation which is an alternate for other carbon-based metal oxides. In addition, the resulting N-CDs were utilized as a fluorescence probe for cellular imaging, owing to their tremendous properties such as bright fluorescence with high quantum yield, excellent water solubility, and good biocompatibility. The N-CDs displays a multicolour fluorescence based on their changing of excitation wavelength and these multicolour fluorescence emissions offered a multicolour cellular imaging which could be applicable for real biological system in the near future.

Individual variation in growth factor concentrations in platelet-rich plasma and its influence on human mesenchymal stem cells.

Abstract: Background The objective of this study was to explore whether individual variations in the concentration of growth factors (GFs) influence the biologic effects of platelet-rich plasma (PRP) on human mesenchymal stem cells (HMSCs). Methods The concentrations of 7 representative GFs in activated PRP (aPRP) were measured using ELISA. The effects of PRP on the proliferation and alkaline phosphatase (ALP) activity of HMSCs were examined using several concentrations of aPRP from 3 donors; the relationships between the GF levels and these biologic effects were then evaluated using 10% aPRP from 5 subgroups derived from 39 total donors. HMSCs were cultured in DMEM with the addition of aPRP for 4 or 12 days; then, DNA content and ALP activity were measured. Results The quantity of DNA increased significantly at a 10% concentration of aPRP, but the ALP activity was suppressed at this concentration of aPRP. The GF concentrations varied among donors, and 5 subgroups of characteristic GF release patterns were identified via cluster analysis. DNA levels differed significantly between groups and tended to be higher in groups with higher concentrations of transforming growth factor-beta1 (TGF-β1) and platelet-derived growth factors (PDGFs). DNA quantity was positively correlated with TGF-β1 concentration, and was negatively correlated with donor age. ALP activity was negatively correlated with PDGF-BB concentration. Conclusions The varying GF concentrations may result in different biologic effects; thus, individual differences in GF levels should be considered for reliable interpretation of the biologic functions and standardized application of PRP.