Self-Assembly of Plodia interpunctella Silk Particles: Mechanisms and Encapsulation Strategies

Silk proteins represent a unique class of biopolymers produced by arthropods that can be leveraged to form a wide range of biomaterials, including particles at the nano- and micro-scale. Silk-derived particles are stable, biodegradable into amino acids, and can entrap and stabilize cargo for applications in healthcare, agriculture, and advanced materials. The utility of silk particles stems from their inherent protein folding, leading to crystalline domains that kinetically trap and stabilize cargoes. Organization and presence of these domains is dependent on synthesis methodology, protein composition (silk fibroin, silk sericin, silk composites), and encapsulated cargo molecules. Herein, we evaluate regenerated silk particles derived from Plodia interpunctella silk through mechanisms of phase separation and nanoprecipitation with and without small molecule encapsulants. Shifts in particle properties are expected to result from silk fiber source, mechanism of protein self-assembly between particle synthesis methods, and cargo molecule encapsulation. The morphology, crystallinity, size, dispersity, and zeta potential of particles derived from non-degummed P. interpunctella silk fibers exhibit distinct properties from degummed B. mori silk fibroin particles. P. interpunctella silk particles are capable of encapsulating small molecules of varying size, hydrophobicity, and charge with high efficiency. This study investigates silk-based biomaterials derived from native, non-degummed Plodia interpunctella silk fibers and demonstrates that protein composition and structural motifs of P. interpunctella silk fibroin influence particle formation and properties. Use of non-degummed silk fibers reduces the processing time required to regenerate silk proteins into biomaterials, offering a promising platform for expanding the functional space of silk-based biomaterials.