Co-assembly, spatiotemporal control and morphogenesis of a hybrid protein-peptide system.

Controlling molecular interactions between bioinspired molecules can enable the development of new materials with higher complexity and innovative properties. Here we report on a dynamic system that emerges from the conformational modification of an elastin-like protein by peptide amphiphiles and with the capacity to access, and be maintained in, non-equilibrium for substantial periods of time. The system enables the formation of a robust membrane that displays controlled assembly and disassembly capabilities, adhesion and sealing to surfaces, self-healing and the capability to undergo morphogenesis into tubular structures with high spatiotemporal control. We use advanced microscopy along with turbidity and spectroscopic measurements to investigate the mechanism of assembly and its relation to the distinctive membrane architecture and the resulting dynamic properties. Using cell-culture experiments with endothelial and adipose-derived stem cells, we demonstrate the potential of this system to generate complex bioactive scaffolds for applications such as tissue engineering.

Effective and durable genetic modification of human mesenchymal stem cells via controlled release of rAAV vectors from self-assembling peptide hydrogels with a maintained differentiation potency.

Controlling the release of recombinant adeno-associated virus (rAAV) vectors from biocompatible materials is a novel, attractive approach to increase the residence time and effectiveness of a gene carrier at a defined target site. Self-assembling peptides have an ability to form stable hydrogels and encapsulate cells upon exposure to physiological pH and ionic strength. Here, we examined the capacity of the peptide hydrogel RAD16-I in a pure (RAD) form or combined with hyaluronic acid (RAD-HA) to release rAAV vectors as a means to genetically modify primary human bone marrow-derived mesenchymal stem cells (hMSCs), a potent source of cells for regenerative medicine. Specifically, we demonstrate the ability of the systems to efficiently encapsulate and release rAAV vectors in a sustained, controlled manner for the effective transduction of hMSCs (up to 80%) without deleterious effects on cell viability (up to 100%) or on their potential for chondrogenic differentiation over time (up to 21days). The present study demonstrates that RAD16-I is an advantageous material with tunable properties to control the release of rAAV vectors as a promising tool to develop new, improved therapeutic approaches for tissue engineering in vivo.

Nanostructuring of ionic bridged silsesquioxanes.

The transformation by hydrolysis/condensation of four new mesityl-(bis or tris)imidazolium-based alkoxysilane precursors into their corresponding bridged silsesquioxanes has been investigated. These precursors feature urea groups and either short or long alkylene chains, which are known to favor self-assembly. The most regular nanostructures were obtained by a combination of the tripodal precursors with C10H20 alkylene chains, as shown by powder X-ray diffraction (PXRD) analysis, independent of the reaction conditions.