Tunable Silk: Using Microfluidics to Fabricate Silk Fibers with Controllable Properties

Abstract

Despite widespread use of silk, it remains a significant challenge to fabricate fibers with properties similar to native silk. It has recently been recognized that the key to tuning silk fiber properties lies in controlling internal structure of assembled β-sheets. We report an advance in the precise control of silk fiber formation with control of properties via microfluidic solution spinning. We use an experimental approach combined with modeling to accurately predict and independently tune fiber properties including Young’s modulus and diameter to customize fibers. This is the first reported microfluidic approach capable of fabricating functional fibers with predictable properties and provides new insight into the structural transformations responsible for the unique properties of silk. Unlike bulk processes, our method facilitates the rapid and inexpensive fabrication of fibers from small volumes (50 μL) that can be characterized to investigate sequence-structure-property relationships to optimize recombinant silk technology to match and exceed natural silk properties.

Development of New Smart Materials and Spinning Systems Inspired by Natural Silks and Their Applications

“…Silk formation of a MaSp2 analog has been achieved using this device under similar condition to natural spider spinning duct. Kinahan et al (2011) designed a microfluidic chip with a cross channel to prepare strong artificial silk fibroin fiber. PEO solution was chosen as the outer stream to apply shear stress on the silk fibroin core stream, and methanol bath was used to collect, dehydrate, and crystallize silk fiber.…”

Advances in Bio-inspired Tribology for Engineering Applications

“…The most significant research on the synthesis of spider fibers has emerged in the field of microfluidics [63]. This research gives a tunable fabrication process which allows the fibers to be customized.…”

“…And that list is just the tip of the iceberg. The researchers at Bolt Threads are not the only ones pioneering the spider silk revolution [63].…”

With great structure comes great functionality: Understanding and emulating spider silk

“…96,97 The quest to recreate the spinning conditions that would allow us to match, or even exceed, the properties of native spider silks remains in its infancy and is largely in the domain of intellectual property rather than the scientific literature. 98,99 A promising approach to fiber synthesis is emerging from the field of microfluidics, 100 which provides a tunable fabrication process that allows for customizable fiber formation. Recently, microfluidic strategies have been used to explore biomimetic spinning on microchips.…”

“…Although this work is preliminary in nature, these advances also provide a platform to explore the spinning process, allowing further understanding and optimization. Krishnaji et al, 48 for example, have used a range of experimental and computational approaches to understand the relationship between structure and function in recombinant silk-like block copolymers that were spun with a tunable microfluidic approach, 100 yet did not report the effects of spinning conditions. A combined investigation of processing, design, structure, and function will substantially advance the field.…”