Fabrication of precise shape-defined particles of silk proteins using photolithography

Abstract Non-spherical particles of different shapes have unique properties potentially beneficial in self-assembly, biosensing, therapeutic delivery and optical applications. Forming particles with precisely controlled physical and chemical characteristics, particularly using bioinspired or bio-derived materials can open up applications inaccessible to synthetic polymers. Here, a high throughput fabrication process of different shapes of protein-based particles at high resolution using photolithography is demonstrated. In contrast to synthetic polymers, the particles shown herein are comprised of the two silk proteins – fibroin and sericin. The demonstrated technique of silk protein lithography allows fabrication of monodisperse biopolymer particles with precise geometries ranging from a few to hundreds of microns. Large numbers of particles of controllable aspect ratios can be easily formed, collected and mixed. The particles themselves are mechanically robust and biocompatible, but can be proteolytically degraded over a period of weeks. Owing to the facile fabrication technique that uses benign solvents, bioactive molecules can be encapsulated within these protein matrices. By control of shape, size, thickness and surface properties, particles that may be harvested for optics, delivery or presentation of biologically functional agents, among other applications.