Jyotsnendu Giri, Wojtek Tutak, Marcus T. Cicerone

The aim of the tissue engineer to develop functional scaffold with adequate close mimic of highly heterogeneous physical (topography) and chemical (functional groups and molecules like proteins etc.) features of natural extracellular matrices (ECM) to encourage cells for regeneration of the specific functional tissues, is obligatory and challenging. Most of the current scaffold fabrication techniques have been focused to mimic the physical structure of natural ECM (i.e., topological features) in the scaffold. Conversely to introduce the chemical feature into the scaffold, most common post-chemical modification of fabricated scaffold has been used. In this process, it is difficult to introduce multi-chemical functionality into a scaffold. Thus the current scaffold fabrication methods have limitation in fabrication of 3D scaffold having both physical and heterogeneous chemical features in a scaffold. We have developed a novel fabrication technique of nanofiber-pocket 3D scaffold where each fiberís pocket (>100 Ķm) in 3D can have different physical and chemical signatures. This technique has four distinct process steps; nanofibers preparation, chemical modification of the nanofibers, protection of the fiber by encapsulation into NaCl crystal, and arranging the fibers in 3D and unprotecting the fibers.  The nanofibers are encapsulated into the NaCl crystal to protect from solvents and the encapsulated fiber-NaCls crystals are used for 3D scaffold fabrication by salt-leached techniques. The NaCl crystals protect nanofibers from array of organic solvents and preserving their physical and chemical signature during the scaffold processing and carry into the 3D scaffold. This is a generic technique that allows us to fabricate a 3D nanofibers scaffold of any single or combination of polymers systems with chemical heterogeneity (encapsulated/immobilized growth factors, proteins and biomolecules for specific cell functions and fate) in 3D. The scaffold prepared in our technique has superior mechanical and cell penetration properties than the conventional electrospun nanofiber scaffold. Using this technique we prepared scaffold with specific chemical functionality in 3D for particular cellular function such as targeting the stem cell to specific site of scaffold in 3D.