Rüdiger Landers

Rapid prototyping of scaffolds derived from thermoreversible hydrogels and tailored for applications in tissue engineering.

In the year 2000 a new rapid prototyping (RP) technology was developed at the Freiburg Materials Research Center to meet the demands for desktop fabrication of scaffolds useful in tissue engineering. A key feature of this RP technology is the three-dimensional (3D) dispensing of liquids and pastes in liquid media. In contrast to conventional RP systems, mainly focused on melt processing, the 3D dispensing RP process (3D plotting) can apply a much larger variety of synthetic as well as natural materials, including aqueous solutions and pastes, to fabricate scaffolds for application in tissue engineering. For the first time, hydrogel scaffolds with a designed external shape and a well-defined internal pore structure were prepared by this RP process. Surface coating and pore formation were achieved to facilitate cell adhesion and cell growth. The versatile application potential of new hydrogel scaffolds was demonstrated in cell culture.

Fabrication of soft tissue engineering scaffolds by means of rapid prototyping techniques

Scaffolds are of great importance for tissue engineering because they enable the production of functional living implants out of cells obtained from cell culture. These scaffolds require individual external shape and well defined internal structure with interconnected porosity. The problem of the fabrication of prototypes from computer assisted design (CAD) data is well known in automotive industry. Rapid prototyping (RP) techniques are able to produce such parts. Some RP techniques exist for hard tissue implants. Soft tissue scaffolds need a hydrogel material. No biofunctional and cell compatible processing for hydrogels exists in the area of RP. Therefore, a new rapid prototyping (RP) technology was developed at the Freiburg Materials Research Center to meet the demands for desktop fabrication of hydrogels. A key feature of this RP technology is the three-dimensional dispensing of liquids and pastes in liquid media. The porosity of the scaffold is calculated and an example of the data conversion from a volume model to the plotting path control is demonstrated. The versatile applications of the new hydrogel scaffolds are discussed, including especially its potential for tissue engineering.

Desktop manufacturing of complex objects, prototypes and biomedical scaffolds by means of computer‐assisted design combined with computer‐guided 3D plotting of polymers and reactive oligomers

Computer-assisted design and image processing were combined with computer-guided one and two-component air-driven 3D dispensing of hotmelts, solutions, pastes, dispersions of polymers as well as monomers and reactive oligomers to produce solid objects with complex shapes and tailor-made internal structures. During the 3D plotting process either individual microdots of microstrands were positioned in order to construct complex objects, fibers, tubes and scaffolds similar to non-wovens. The resolution was in the range of 200 μm and depended upon inner nozzle diameter, air pressure, plotting speed, rheology, and plotting medium. Plotting in liquid media with densities similar to that of the dispensing liquid eliminiated the need for construction of temporary support structures. The design capabilities of this computer-guided 3D plotting process was demonstrated using conventional moisture-curable silicone resin.