Two-photon Polymerization as Method for the Fabrication of Large Scale Biomedical Scaffold Applications

Abstract

Two-photon polymerization (2PP) using ultra-short laser pulses is a well-known methodology for the 3D free-form fabrication of optical devices with resolutions down to 100 nm. However, the structure dimensions have been restricted to quite small sizes, mainly due to limitations of the focussing optics and due to very long fabrication times. Therefore, the largescale fabrication of biomedical scaffold structures with dimensions in the mm-range still remains challenging. Using a diode-pumped Ytterbium laser system emitting 325 fs laser pulses at 515 nm after second harmonic generation we are able to write arbitrary 3D structures in inorganic-organic hybrid polymers (ORMOCERs). Our setup is able to produce structures with mm extension normal to the substrate at a structural resolution of a few microns. In particular, a 3D porous inner structure can be provided, which is required for three-dimensional cell growth to support cell adhesion and proliferation. Scaffold structures were produced with different parameters, and they were characterized in order to demonstrate their potential concerning resolution and scaffold quality. It is found that not only the experimental setup, but also the substrate material plays an important role for the scaffold fabrication process and structural quality.