During the irradiation of Ge surface with Ga＋ ions up to 1017 ions.cm 2, various patterns from ordered honeycomb to nanograss structure appear to be decided by the ion beam energy. The resulting surface morphologies ...During the irradiation of Ge surface with Ga＋ ions up to 1017 ions.cm 2, various patterns from ordered honeycomb to nanograss structure appear to be decided by the ion beam energy. The resulting surface morphologies have been studied by scanning electron microscopy and atomic force microscopy. For high energy Ga＋ irradiation （16-30 keV）, by controlling the ion fluence, we have captured that the equilibrium nanograss morphology also originates from the ordered honeycomb structure. When honeycomb holes are formed by ion erosion, heterogeneous distribution of the deposited energy along the holes leads to viscous flow from the bottom to the plateau. Redistribution of target atoms results in the growth of protuberances on the plateau, and finally the pattern evolution from honeycomb to nanograss with an equilibrium condition.展开更多
Arginine-glycine-aspartic acid （RGD） dendrimer-based nanopatterns on poly（L- lactic acid） were used as bioactive substrates to evaluate the impact of the RGD local surface density on the chondrogenic induction of ...Arginine-glycine-aspartic acid （RGD） dendrimer-based nanopatterns on poly（L- lactic acid） were used as bioactive substrates to evaluate the impact of the RGD local surface density on the chondrogenic induction of adult human mesenchymal stem cells. During chondrogenic commitment, active extracellular matrix （ECM） remodeling takes place, playing an instructive role in the differentiation process. Although three-dimensional environments such as pellet or micromass cultures are commonly used for in vitro chondrogenic differentiation, these cultures are rather limited with respect to their ability to interrogate cells in celI-ECM interactions. In the present study, the nanopatterns of the tunable RGD surface density were obtained as a function of the initial dendrimer concentration. The local RGD surface density was quantified through probability contour plots for the minimum interparticle distance, constructed from the corresponding atomic force microscopy images, and correlated with the cell adhesion and differentiation response. The results revealed that the local RGD surface density at the nanoscale acts as a regulator of chondrogenic commitment, and that intermediate adhesiveness of cells to the substrates favors mesenchymal cell condensation and early chondrogenic differentiation.展开更多
基金supported by the National Natural Science Funds for Excellent Young Scholar,China(Grant No.51222211)the National Natural Science Foundation of China(Grant Nos.61176001 and 61006088)+4 种基金the National Basic Research Program of China(Grant No.2010CB832906)the Pujiang Talent Project of Shanghai,China(Grant No.11PJ1411700)the Hong Kong Research Grants Council(RGC)General Research Funds(GRF),China(Grant No.112212)the City University of Hong Kong of Hong Kong Applied Research Grant(ARG),China(Grant No.9667066)the International Collaboration and Innovation Program on High Mobility Materials Engineering of Chinese Academy of Sciences
文摘During the irradiation of Ge surface with Ga＋ ions up to 1017 ions.cm 2, various patterns from ordered honeycomb to nanograss structure appear to be decided by the ion beam energy. The resulting surface morphologies have been studied by scanning electron microscopy and atomic force microscopy. For high energy Ga＋ irradiation （16-30 keV）, by controlling the ion fluence, we have captured that the equilibrium nanograss morphology also originates from the ordered honeycomb structure. When honeycomb holes are formed by ion erosion, heterogeneous distribution of the deposited energy along the holes leads to viscous flow from the bottom to the plateau. Redistribution of target atoms results in the growth of protuberances on the plateau, and finally the pattern evolution from honeycomb to nanograss with an equilibrium condition.
文摘Arginine-glycine-aspartic acid （RGD） dendrimer-based nanopatterns on poly（L- lactic acid） were used as bioactive substrates to evaluate the impact of the RGD local surface density on the chondrogenic induction of adult human mesenchymal stem cells. During chondrogenic commitment, active extracellular matrix （ECM） remodeling takes place, playing an instructive role in the differentiation process. Although three-dimensional environments such as pellet or micromass cultures are commonly used for in vitro chondrogenic differentiation, these cultures are rather limited with respect to their ability to interrogate cells in celI-ECM interactions. In the present study, the nanopatterns of the tunable RGD surface density were obtained as a function of the initial dendrimer concentration. The local RGD surface density was quantified through probability contour plots for the minimum interparticle distance, constructed from the corresponding atomic force microscopy images, and correlated with the cell adhesion and differentiation response. The results revealed that the local RGD surface density at the nanoscale acts as a regulator of chondrogenic commitment, and that intermediate adhesiveness of cells to the substrates favors mesenchymal cell condensation and early chondrogenic differentiation.
