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P. Petrochenko, R. Narayan, P. Goering, A. Ovsianikov:
"Laser 3D printing with nanoscale resolution: improving biocompatibility and mitigating toxicity from photoinitiators";
Talk: Symposium on Toxicity Associated with Nanomaterials, USA; 2013-12-16; in: "Symposium on Toxicity Associated with Nanomaterials", (2013).

Three-dimensional (3D) structural features of a scaffold critically influence cellular functions and the overall performance of a scaffold material. Recent developments in laser-assisted 3D printing using two-photon polymerization (2PP) have allowed for previously unattainable submicron resolution and opened a number of possibilities for creating 3D cell scaffolds. However, a significant barrier to using 2PP for biological applications exists due to the toxic nature of photoinitiators required for radical polymerization using light energy. In this study we demonstrate two main approaches for creating nanotextured porous 3D scaffolds. The first involves printing the scaffold beforehand, removing residual toxic substances and seeding cells afterwards. The second, more complex approach, involves using lower laser energy and trapping cells directly in a collagen matrix. Our results from the first method indicate that stable scaffolds with porosities of over 60% can be custom printed to fit standard well plates. Cells grown on 3D scaffolds exhibit increased growth and proliferation compared to smooth 2D scaffold controls. Scaffolds additionally adsorb larger amounts of proteins due to their larger surface area and allow cells to attach in multiple planes and completely infiltrate the porous scaffolds. Preliminary results from the second approach show some dead cells in encapsulated regions. In order to improve cytocompatibility 3 possible antioxidants: Trolox (water-soluble vitamin E), vitamin C, and glutathione; and collagenase are used to mitigate the toxic effects of photoinitiators. Preliminary improved cytotoxicity and encapsulation results are demonstrated. 2PP is shown to be a promising technique for fabricating custom 3D scaffolds from a computer model with potential for in situ cell encapsulation.