Silk-Corn Zein Alloy Materials: Influence of Silk Types (Mori, Thai, Muga, Tussah, and Eri) on the Structure, Properties, and Functionality of Insect–Plant Protein Blends

Biocompatible materials fabricated from natural protein polymers are an attractive alternative to conventional petroleum-based plastics. They offer a green, sustainable fabrication method while also opening new applications in biomedical sciences. Available from several sources in the wild and on domestic farms, silk is a widely used biopolymer and one of the strongest natural materials. This study aims to compare five different types of silk (Mori, Thai, Muga, Tussah, and Eri) fabricated into thin composite films in conjunction with plant-based proteins. To offer a wider range of morphologies, corn zein, another widely available protein material, was introduced into the silk protein networks to form blended polymers with various ratios of silk to zein. This resulted in the successful alloying of protein from an animal source with protein from a plant source. The material properties were confirmed through structural, morphological, and thermal analyses. FTIR analysis revealed the dominance of intramolecular beta-sheet structures in wild silks, while the domestic silks and zein favored random coil and alpha-helical structures, respectively. Post-treatments using water annealing further refined the structure and morphology of the films, resulting in stable composites with both inter- and intramolecular beta-sheet structures in wild silks. While in domestic silks, the random coils were converted into intermolecular beta-sheets with enhanced beta-sheet crystallinity. This improvement significantly enhanced the thermal and structural properties of the materials. By deciding on the source, ratio, and treatment of these biopolymers, it is possible to tailor protein blends for a wide range of applications in medicine, tissue engineering, food packaging, drug delivery, and bio-optics.