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A precursor solution containing poly(vinyl alcohol) and a calcium phosphate sol is used to produce fibers of hydroxyapatite. The mixture is electrospun at a voltage of 20 kV and the resultant structure is calcined at 600°C for 6 h. Experiments were conducted for polymer molecular weight (MW) between 9500 and 155 000 g/mol and sol volume fractions (VS) between 0% and 83%. The results indicate that the electrospun fiber diameter can be correlated to the solution viscosity. The polymer molecular weight and sol volume fraction have a significant effect on the ceramic structure. Highly interconnected solid or porous hydroxyapatite fibers with diameters between 200 and 500 nm and crystal sizes between 30 and 50 nm can be produced by controlling MW and VS.

This paper describes an efficient and versatile method for the fabrication of nanostructured substrates from a piece of tendon which comprises aligned collagen nanofibers. We used a microtome to generate the tendon slices (10-50  µm thick), which were used as a scaffold for guiding directional cell growth. Highly aligned and uniform monolayer cells sheets were obtained. The tendon slices were used as a master, and the nanostructures outlined by the bundles of collagen nanofibers were successfully transferred onto a polystyrene film using standard soft lithography. The cell growing on the nanostructured polystyrene substrate showed good adhesion and alignment. The technique developed here enables one to fabricate nanostructured substrates without using any traditional micro/nanofabrication tools. The nanostructured substrate, e.g. a slice of tendon, has excellent biocompatibility and relatively good mechanical stability, which makes this technique useful in constructing complicated 3D tissues.

In this paper, we describe an electric-field-assisted gel transferring technique for patterning on two- and three-dimensional media. The transfer process starts with the preparation of a block of agarose gel doped with charged nanoparticles or molecules on top of a screen mask with desired patterns. This gel/mask construct is then brought into contact with the appropriate receiving medium, such as a polymer membrane or a piece of flat hydrogel. An electric field is applied to transfer the doped charged nanoparticles or molecules into the receiving medium with a pattern defined by the screen mask. This printing method is rapid and convenient, the results are reproducible, and the process can be done without using expensive micro/nanofabrication facilities. The capability to pattern structures such as arrays of nanoparticles into three-dimensional hydrogels may find applications for positioning cell signaling molecules to control cell growth and migration.