The search for a cell-supporting scaffold with controlled topography and surface chemistry is a constant topic within tissue engineering. Here we have employed M13 phages, which are genetically modifiable biological nanofibers (~880 nm long and ~6.6 nm wide) non-toxic to human beings, to form films for supporting the growth of mesencymal stem cells (MSCs). Films were built from nearly parallel phage bundles separated by grooves. The bundles can guide the elongation and alignment of MSCs along themselves. Phage with peptides displayed on the surface exhibited different control over the fine morphologies and differentiation of the MSCs. When an osteogenic peptide was displayed on the surface of phage, the proliferation and differentiation of MSCs into osteoblasts was significantly accelerated. The use of the grooved phage films allows us to control the proliferation and differentiation of MSCs by simply controlling the concentrations of phages as well as the peptides displayed on the surface of the phages. This work will advance our understanding on the interaction between stem cells and proteins.

No abstract

The potential of CRISPR–Cas9-based therapeutic genome editing is hampered by difficulties in the control of the in vivo activity of CRISPR–Cas9. To minimize any genotoxicity, precise activation of CRISPR–Cas9 in the target tissue is desirable. Here, we show that, by complexing magnetic nanoparticles (MNPs) with recombinant baculoviral vectors (BVs), CRISPR–Cas9-mediated genome editing can be activated locally in vivo via a magnetic field. BV was chosen for in vivo gene delivery because of its large loading capacity and its ability to locally overcome systemic inactivation by the complement system. We demonstrate that a locally applied magnetic field can enhance the cellular entry of MNP-BVs, thereby avoiding BV inactivation and causing a transient transgene expression in the target tissue. Because BVs are inactivated elsewhere, gene delivery and in vivo genome editing via MNP-BVs are tissue-specific.

No abstract

This paper describes a simple, mild, and environmentally friendly approach to synthesize polystyrene/Ag (PS/Ag) nanocomposite spheres, which makes use of both reducing and stabilizing functions of polyvinylpyrrolidone (PVP) in aqueous media. In this approach, monodisperse polystyrene (PS) spheres, which are used as templates for the synthesis of core-shell nanocomposite spheres, are sulfonated first. Then, [Ag(NH(3))(2)](+) ions are adsorbed onto the surface of the PS template spheres via electrostatic attraction between -SO(3)H groups (grafted on the surface of the PS template spheres) and [Ag(NH(3))(2)](+) ions. [Ag(NH(3))(2)](+) ions are then reduced by and simultaneously protected by PVP. In this way, the PS/Ag nanocomposite spheres in aqueous media are obtained through a so-called one-pot method. Neither additional reducing agents nor toxic organic solvents are utilized during the synthesis process. Furthermore, the coverage degree and the particle size of Ag nanoparticles on PS/Ag nanocomposite spheres is easily tuned by changing the concentration of [Ag(NH(3))(2)](+) ions in aqueous media. Moreover, these PS/Ag nanocomposite spheres can be used as catalyst for the reduction of organic dyes and as antibacterial agents against Salmonella and Escherichia coli. In the present study, these PS/Ag nanocomposite spheres exhibit excellent catalytic properties (both in efficiency and recyclability) for the reduction of organic dyes, and the preliminary antibacterial assays indicate that these PS/Ag nanocomposite spheres also possess extraordinary antibacterial abilities against Salmonella and Escherichia coli.