Advances in Two-Photon Initiated Photopolymerization for Tissue Engineering Applications

The process of two-photon induced polymerization (2PP) enables free-form stereolithography with a resolution in the sub-micrometre range. Thus the production of 3D-printed parts containing arbitrary microscopic features, like photonic crystals, optical waveguides and microelectronic components, is possible. Since aqueous media and biological specimen are highly transparent at 800 nm, the emission maximum of the typically used femtosecondpulsed Ti:Sapphire lasers, the 2PP process is especially attractive for creating tissue engineering constructs in the presence of living cells. For this application the versatility of the 2PP process is combined with functional materials to allow tuning of mechanical properties and biochemical triggers pertaining to the microenvironment of the encapsulated cells, thus guiding their development.