Exploring New Sources of Silk Fibroin for Biomaterials Applications

Silk fibroin from Bombyx mori silkworms has been widely studied for tissue engineering applications,[1] exploring the properties of silk materials[2, 3]. Silk fibroin produced by other moths have not been explored to the same extent.[4] Thus, we aim to explore the properties of silk fibroin produced by the Indianmeal moth (Plodia interpunctella) (IMM). The current project is part of a joint effort with the overall objective to study the silk-producing order Lepidoptera. Investigation of IMM was prioritized because, under certain habitats and culture conditions, the IMM produces silk sheets covering their food source and enclosure, a behavior that is not fully understood. This silk fibers are produced throughout the larval stage and thus we hypothesize that these silk fibers have differing chemical composition compared to the silk produced to form cocoons during the pupal stage. It is already known that the ratio of light and heavy chain silk fibroin directly impacts the chemical and mechanical properties of silk [5, 6]. Previous work in Bombyx mori has demonstrated that silk fiber properties can be controlled through manipulation of the environment or via gene editing [7]. Thus, we hypothesized that controlling population dynamics and resource availability will directly impact the silk production of the IMM. Our ultimate goal is to use these silks to expand the array of silk fibroin-based tunable biomaterials for use in in tissue engineering or bioprinting.

To test our hypothesis, we systematically changed IMM living conditions and analyzed silk production. For these studies, we specifically altered the number of caterpillars in the colony, mass of food added to the habitat, and the size of their habitat. Results suggest that the mass of silk produced directly correlates to the number of caterpillars in the starting colony. Additionally, we determined that the silk fibers are deposited in an organized pattern, suggesting that the caterpillars are working together to respond to the stresses in their habitat. On going and future work is aimed at chemically and mechanically analyzing the silk fibers produced by Indianmeal moths.