Our lab has developed a new solid freeform fabrication technology capable of printing curable emulsion inks to fabricate complex materials with hierarchical porosity. Briefly, an emulsion ink based on a high internal phase emulsion (HIPE) is deposited layer-by-layer using an open source 3D printer equipped with a syringe and motor-actuated plunger. Emulsions inks are rapidly cured after deposition by constant UV irradiation to form rigid constructs with interconnected porosity in a method we term Cure-on-Dispense (CoD) printing, Figure 1. 3D printed polyHIPE constructs benefit from the tunable pore structure of emulsion templated materials and the fine control over complex geometries of 3D printing that is not possible with traditional manufacturing techniques. In this study, we report on the in situ surface modification of these 3D printed grafts by incorporating bioactive hydrogel precursors into the aqueous phase of the emulsion inks prior to cure. Hydrogel precursor solutions containing 2.5 wt% of polyethylene glycol diacrylate (PEGDA) with or without 2.5 wt% extracellular matrix protein (gelatin or collagen) were investigated. During the HIPE cure, a hydrogel coating of the pore surface was formed as radical initiation of the precursor solution occurred at the droplet interface. After printing, PEGDA coating was confirmed with ATR-FTIR spectroscopy and PicoSirius Red staining was used to verify successful incorporation of the protein, Figure 1. Standard cell culture methodology established in our lab was used to investigate integrin-mediated osteogenic differentiation of human mesenchymal stem cell cultured on polyHIPE grafts. Overall, these studies demonstrate our ability to print porous materials using emulsion inks and improve cell-material interactions via incorporation of ECM proteins. These scaffolds have a great potential to improve clinical outcomes for treatment of critical size bone defects due to their composite, biomimetic nature.

In situ surface modification of 3D printed emulsion inks

2019 Fall National Meeting

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