Biomimetic modifications to microfluidic silk spinning
Silk fibers from arthropods possess several favorable properties for biomedical applications, including high mechanical strength and biocompatibility. However, the majority of silk fiber production is currently limited to manipulation of cocoons from the Bombyxmori silkworm. The efficiency of the process can be increased by dissolving waste silk threads and using artificial spinning techniques to spin the proteins back into usable fibers. Once an artificial spinning technique has been perfected, it may be possible to use similar designs to spin recombinant silk proteins into threads with more favorable mechanical properties. The first step towards customizable silk is to artificially spin silk protein into fibers with comparable properties to naturally-derived silk threads. Current microfluidic devices are limited to spinning B. mori silk into weak, poorly-formed fibers. The incorporation of silk gland-like ion gradients and high shear stress into current and novel microfluidic devices is theorized to improve mechanical properties of resultant spun silk. To this end, ion gradients were added to the current microfluidic device. In addition, a novel microfluidic device was developed to increase shear stress. After investigating the individual effects of ion gradients and shear stress on the silk spinning process, an integrated microfluidic device was designed to investigate the combined effects. Computational models of the flow within each microfluidic device were generated and used to predict biomimetic design parameters. Measurements of fiber diameter and pH within the microfluidic devices were collected to verify the accuracy of the computational models. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and mechanical testing measurements were collected to characterize and compare resultant fibers. From these results, relationships were found between the incorporation of ion gradients and shear stress into the spinning process and the properties of the fibers produced.
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