Pressureless mechanical induction of stem cell differentiation is dose and frequency dependent

Movement is a key characteristic of higher organisms. During mammalian embryogenesis fetal movements have been found critical to normal tissue development. On the single cell level, however, our current understanding of stem cell differentiation concentrates on inducing factors through cytokine mediated biochemical signaling. In this study, human mesenchymal stem cells and chondrogenesis were investigated as representative examples. We show that pressureless, soft mechanical stimulation precipitated by the cyclic deformation of soft, magnetic hydrogel scaffolds with an external magnetic field, can induce chondrogenesis in mesenchymal stem cells without any additional chondrogenesis transcription factors (TGF-ß1 and dexamethasone). A systematic study on the role of movement frequency revealed a classical dose-response relationship for human mesenchymal stem cells differentiation towards cartilage using mere mechanical stimulation. This effect could even be synergistically amplified when exogenous chondrogenic factors and movement were combined

Permanent Pattern-Resolved Adjustment of the Surface Potential of Graphene-like Carbon through Chemical Functionalization

Beyond the age of silicon: A combination of radical chemistry under standard conditions and clean-room lithography can alter the electronic structure of graphene layers permanently through covalent chemical functionalization. The potential change follows the Hammett correlation. This simple method is a promising approach for graphene-based electronics