α-Zein, an edible prolamine protein generally recognized as safe (GRAS), is a well research protein material in the field of biomaterials for cell culture applications. Obtained from the corn kernel and available at an industrial scale, it is a water-insoluble protein with good viscoelastic properties. These properties make it suitable for efficient fiber fabrication and the development of an edible 3D scaffold with defined parameters, offering exciting possibilities for cell culture in tissue engineering.
 
However, the zein fiber is strongly hydrophobic, and the 3D scaffolds deform significantly in aqueous cell culture media. To improve the scaffold compatibility with the culture media, we have introduced a small molecular coating on the zein fiber using Tannic acid (synonymous with Tannin), a naturally occurring phenol compound in all fruits and herbs (e.g., grapes, banana, chocolate, cocoa, coffee, etc.).
 
Tannic acid is used widely as a protein crosslinker through  hydrogen bonding, electrostatic, and hydrophobic interactions with stronger affinity to the proline amino acids (DOI: 10.1039/d2tb01056a)
 
Currently, the tannin-coated zein fibers are recommended to use only with L-15 medium (Leibovitz) cell culture media.