Three-Dimensional Printing Using a Maize Protein: Zein-Based Inks in Biomedical Applications

Abstract

The use of three-dimensional (3D) printing for biomedical applications has expanded exponentially in recent years. However, the current portfolio of 3D printable inks is still limited. For instance, only few protein matrices have been explored as printing/bioprinting materials. Here, we introduce the use of zein, the primary constitutive protein in maize seeds, as a 3D printable material. Zein-based inks were prepared by dissolving commercial zein powder in ethanol with or without polyethylene glycol (PEG400) as a plasticizer. The rheological characteristics of our materials, studied during 21 days of aging/maturation, showed an increase in the apparent viscosity as a function of time in all formulations. The addition of PEG400 decreased the apparent viscosity. Inks with and without PEG400 and at different maturation times were tested for printability in a BioX bioprinter. We optimized the 3D printing parameters for each ink formulation in terms of extrusion pressure and linear printing velocity. Higher fidelity structures were obtained with inks that had maturation times of 10 to 14 days. We present different proof-of-concept experiments to demonstrate the versatility of the engineered zein inks for diverse biomedical applications. These include printing of complex and/or free-standing 3D structures, tablets for controlled drug release, and scaffolds for cell culture.

Water-responsive 4D printing based on self-assembly of hydrophobic protein “Zein” for the control of degradation rate and drug release

“…2 b). Values of yield stresses were found to be superior to previously reported zein gel [ 26 ]. The difference in the preparation method was a possible reason for the superior rheological properties.…”

“…Our group submitted a patent application for the 3D printing application of zein gel for the first time [ 25 ]. Recently, Tavares-Negrete et al reported zein gel as 3D printing ink that demonstrated slow gelation (21 d) and low yield stress (<30 Pa), and the printed structures exhibited cell adhesion and proliferation properties [ 26 ]. Zein can self-assemble in water because of its hydrophobic nature.…”

A Proteomic Approach to Identify Zein Proteins upon Eco-Friendly Ultrasound-Based Extraction

“…Zein proteins have found wide applications as excipients in the production of inks [ 9 ], adhesives [ 10 ], water resistant paper coating [ 11 , 12 ], plastic-free replacement [ 13 ], encapsulated foods [ 14 ], and a controlled release matrix of active medical components [ 15 , 16 , 17 , 18 ]. Moreover, among various protein sources, zein (the primary storage protein in corn endosperm) has been extensively studied for its capacity to create innovative polymeric films, a feature we want to explore in the future [ 19 , 20 , 21 ].…”

Fabrication of Zein‐Based Fibrous Scaffolds for Biomedical Applications—A Review

“…Commercial zein in powder form dissolved in ethanol and a plasticizer demonstrated shear thinning properties and hence can be used as a medium suitable for printing. [100,101] A recent study by Ruther et al in 2022 reported 3DP of poly(glycerol sebacate) (PGS)/zein/NaCl inks to produce the scaffold intended for cardiac tissue engineering (as shown in Figure 4a). Improved printability, shape fidelity, and thermal cross-linking could be achieved by adding the protein corn zein and ground NaCl particles with the PGS pre-polymer.…”