Natural silk has incredible mechanical properties of strength, elasticity, and durability. For this reason it is being utilized for 3D printing in hopes to optimize these properties. In addition to its mechanical properties, extracted silk possesses excellent biocompatibility and therefore it has many possible applications in medicine such as in bone graft surgeries, drug delivery, and other procedures. The objective of this project was to create a silk 3D printing method that allows for customization of desired properties for biomedical applications. In order to transition the silk protein solution from a liquid to a solid fiber during printing, known as beta sheet formation, a specific coagulating bath composition which yields the best mechanical properties had to be determined. After reading the literature it was hypothesized a coagulating bath composed of 80% ethanol mixed with 30% acetic acid would produce fibers with optimal mechanical properties. Extracting silk from the cocoons to create a printable material involved degumming the sericin from the silk and using a dialysis process to reach a preferred concentration. Once the silk “ink” solution was ready to print, it was extruded into one of 4 different baths composed of: 86% methanol, 86% ethanol, 80% ethanol mixed with 30% acetic acid, or 30% ammonium sulfate. Upon qualitative comparison it was determined that the ammonium sulfate coagulating bath produced the fiber with the most desirable mechanical properties. Mechanical testing of this fiber was conducted, and the results were comparable to some silk fiber tensile behaviors reported in literature. Future research will investigate the effect of exposure time in the ammonium sulfate bath on fiber structure and mechanical properties. Fiber structure at different exposure times will be analyzed with infrared spectroscopy, and future mechanical testing will be carried out in water to better simulate the environment of the human body.
Authors: Niusha Daneshdoost, Aidan Kuhn, Maria Menke, Annie Nguyen
Faculty Advisor: Dr. Jessica Sparks, Department of Bioengineering
You must be logged in to post a comment.