(520d) Biofabrication Using Corn Protein: 3D Printing of Zein and Zein-Peg Formulations

The use of three-dimensional printing for biomedical applications has gained popularity in recent years. However, the current portfolio of 3D printable inks is still limited. For instance, only a few protein matrices have been explored as printing/bioprinting materials. Here, we introduce the use of zein, the primary constitutive protein in maize grains, as a 3D-printable material. Zein-based inks were prepared by dissolving commercial zein powder in ethanol and, optionally, adding poly-ethylene glycol (PEG400) as a plasticizer. The rheological evolution of our materials was studied from 0 to 21 days. Our results showed an increase in the apparent viscosity as a function of time in all our formulations. The addition of PEG 400 also led to a decrease in the apparent viscosity and an attenuation of the shear-thinning behavior when compared to inks without this plasticizer. Inks with and without PEG 400 and at different times of maturation were tested for printability in a commercial BioX bioprinter (Cellink, Sweden). We determined optimized 3D printing parameters for each ink in terms of extrusion pressure and printing linear velocity. Higher resolution structures were obtained with inks that had 11 to 14 days of maturation time.

Here, we present different proof-of-concept experiments that demonstrate the versatility of our zein-inks for diverse biomedical applications, such as printing of complex and/or self-standing 3D structures, controlled drug release, and fabrication of scaffolds for cell culture. Our results confirm that zein-bioprinted constructs used for drug release applications reduced bacterial growth in vitro. Similarly, when used as tissue engineering scaffolds after coating with fibronectin, our printed zein constructs enabled cell attachment and spreading over 7 days. Given that zein is recognized as safe by the FDA, 3D printing with zein-based inks will open the door for versatile applications in diverse fields, especially biomedical applications.