Three-dimensional laser micro- and nano-structuring of acrylated poly(ethylene glycol) materials and evaluation of their cytoxicity for tissue engineering applications

Abstract

The natural cell environment is characterised by complex three-dimensional structures, which contain features at multiple length scales. Many in vitro studies of cell behaviour in three dimensions rely on the availability of artificial scaffolds with controlled three-dimensional topologies. In this paper, we demonstrate fabrication of three-dimensional scaffolds for tissue engineering out of poly(ethylene glycol) diacrylate (PEGda) materials by means of two-photon polymerization (2PP). This laser nanostructuring approach offers unique possibilities for rapid manufacturing of three-dimensional structures with arbitrary geometries. The spatial resolution dependence on the applied irradiation parameters is investigated for two PEGda formulations, which are characterized by molecular weights of 302 and 742. We demonstrate that minimum feature sizes of 200 nm are obtained in both materials. In addition, an extensive study of the cytotoxicity of the material formulations with respect to photoinitiator type and photoinitiator concentration is undertaken. Aqueous extracts from photopolymerized PEGda samples indicate the presence of water-soluble molecules, which are toxic to fibroblasts. It is shown that sample aging in aqueous medium reduces the cytotoxicity of these extracts; this mechanism provides a route for biomedical applications of structures generated by 2PP microfabrication and photopolymerization technologies in general. Finally, a fully biocompatible combination of PEGda and a photoinitiator is identified. Fabrication of reproducible scaffold structures is very important for systematic investigation of cellular processes in three dimensions and for better understanding of in vitro tissue formation. The results of this work suggest that 2PP may be used to polymerize poly(ethylene glycol)-based materials into three-dimensional structures with well-defined geometries that mimic the physical and biological properties of native cell environments.

Joint Cartilage Tissue Engineering and Pre-Clinical Safety and Efficacy Testing

“…In the latter case, 3D scaffolds with feature dimensions in the range of ECM have been recently fabricated by two-photon polymerization (2PP). This technology exploits in situ polymerization of photosensible polymers at specific wavelengths (Ovsianikov et al, 2011). With 2PP, a number of rather complex structures can be fabricated with nanometric resolution (Ovsianikov et al, 2010).…”

Microfabrication of 3D metallic interconnects via direct laser writing and chemical metallization

“…As the majority of the materials are bio-compatible [16,17], this approach was employed for the manufacturing of artificial scaffolds for cell proliferation studies [18,19], medical implants for tissue engineering [20,21] as well as regenerative medicine [22,23]. In all of the mentioned examples the materials were passive polymers sensitized only with a photoinitiator responsible for the efficient photostructuring [24].…”

Polylactide-Based Biodegradable Scaffolds Fabricated by Two-Photon Polymerization for Neurotransplantation

“…These features, along with compatibility with biomaterials, make 2PP method most perspective for solving the problems of creating matrices of the required form and inner architecture for the needs of regenerative medicine [5,6]. Complex, porous 3D scaffolds produced by 2PP are especially important for cell culturing in terms of transport of the nutrients within cultured construct [7].…”