Combination of nanotechnology with cell and tissue engineering is the forefront in nanomedicine that can improve quality of life for cancer patients suffering from disability and disfigurement due to large tissue defects. The ideal way of reconstructing such defects would be to stimulate and guide the body's capacity to regenerate although most currently available biomaterials used in areas of reconstruction, repair, and artificial devices are not designed to regenerate tissue but to cover or fill defects and/ or perform a mechanical function. Our aim is to design biomaterials that would not only reconstruct but regenerate tissue when implanted in vivo by surrendering control of the regenerative process to the wound healing cells that interface their anchoring matrix/ substrate/ biomaterial at a nano-interface (cell-substrate adhesions). The question to ask is why and how are regeneration and repair controlled at the nano-scale in the tissue? Do we have the means and tools to study this delicate interface in an in vivo environment?

Research done in our lab suggests that scaffolds composed of a blend of the natural polymers, silk fibroin (SF) and chitosan (CS), offer desirable scaffold properties for tissue regeneration (Gobin et al. 2005). Silk fibroin is a fibrous protein that forms nanofibrils on the order of 50-100 nm due to its liquid crystalline nature in a resident matrix of chitosan, glucosamine, that has the capacity to store water, act as a reservoir for growth factors, has compressive strength, and has been shown to have wound healing properties.

In the proposed study, we use dielectrophoresis to induce the formation and alignment of silk fibroin nanofibrils (height 35 nm, width <2 urn) that make up larger microfibrils and assemble within the sheets ofthe threedimensional scaffold. We propose to utilize these nano-structured scaffolds to study the formation and assembly of blood vessels via near infrared (NIR) confocal in vivo imaging. We hypothesize that aligned nanofibrils in the SFCS scaffold will guide in vivo cell and blood vessel assembly. We propose two specific aims to address this hypothesis. Specific Aim 1: Construct three dimensional nano-structured scaffolds of known geometry with silk fibroin-chitosan blends using dielectrophoresis. Specific Aim 2: Study the in vivo guidance of blood vessel assembly along the nano-fibrils of the SFCS scaffold by in vivo confocal near infrared (NIR) microscopic imaging and histomophometric analysis using a rat mesentery in vivo model.

Regenerative tissue engineering at the nano-scale has the potential to revolutionize reconstructive approaches by providing either prefabricated tissue or responsive biomaterials with patient-specific geometry.