(164f) Novel Micro and Nano Fabrication Technology Based on Self-Organization for Biomaterials and Nano-Particles

The design of nano- and microstructures by self-organization is one of the most important issues for creating new materials. This design has a variety of potential applications in biomaterials. At first, we describe the fabrication and characterization of highly regular porous surfaces (honeycomb-patterned films) formed by a solution casting (bottom up) technique under humid air condition. Condensation of water from the air due to evaporation cooling was occurred when water-immissible solvent was used. Self-packed and mono-dispersed water droplets formed on the solution surface act as a temporary template of pores. Various experimental factors affecting the pore structures were studied. The honeycomb-patterned film shows a highly regular hexagonal arrangement of holes in a large area and can be easily peeled off from a substrate as a self-supported film. The pore size can be controlled in the range from 100 nm to 50 um by changing the casting conditions. Unlike other templated or lithographic methods, advantage of this method is ease with which such patterned surfaces can be created using various materials. The honeycomb-patterned films have a strong influence on the cell attachment and functions. Hepatocytes were flattened, and the actin filaments appeared conspicuously in the spreading regions on a flat film. In contrast, the hepatocytes that were cultured on the honeycomb-patterned film were observed to form a spherical shape, and the actin filaments were localized inside the edge of the spheroid. The spheroids were observed within several hours after seeding on the honeycomb-patterned film; they were attached and the spheroid shape was maintained without any deformation. The spheroids expressed a higher level of liver specific function than the cell monolayers on the flat film. The honeycomb-patterned films with different pore size were prepared in order to investigate the influence of pore size on porcine arterial endothelial cells (PAECs) behavior. Changes in cell morphology, proliferation, cytoskeleton and extra cellular matrix (ECM) (fibronectin, laminin, type IV collagen, elastin) production profiles were observed by optical, fluorescence, and scanning electron microscopy. The degree of spreading of PAECs was enhanced with increase of the pore size. Cell proliferation and ECM production profiles were the highest on the honeycomb-patterned film with a pore size of 5 um. The neurons were round and the neurites extended randomly on the flat film. The patterns influenced the morphologies of neurons. The morphologies of neurons were changed by varying the pore size of the honeycomb-patterned films. The neurites spread via the rims of the honeycomb pattern. These results suggest that the honeycomb-patterned film is suitable as a material of new tissue engineering and medical devices. In addition, we will report a novel and simple formation of nano-particles by mixing a poor solvent into a solution of polymer and then evaporating a good solvent. The nano-particles were prepared from various biodegradable polymers. Average size and zeta potential of the particles were measured by using a dynamic light scattering spectrophotometer and an electrophoretic light scattering spectrophotometer, respectively. The particles were observed by using a Field-Emission Scanning Electron Microscope. The particles with uniform size were formed from various polymers. The particle size was controlled in the range from 100 to 1000 nm. The particle size became larger with increasing the concentration of solution and the volume ratio of a good solvent / a poor solvent. Fabrication of biodegradable particles containing a drug will be reported.