BRIGE: Hagfish Defense Gel and the Rheology Zoo

背景：盲鳗是一种独特的材料，具有显着的性能。 当受到挑衅或攻击时，动物会释放少量的生物聚合物/生物丝材料，这些材料在水中展开，组装并膨胀10，000倍。 由此产生的凝胶是粘性的，形成用于防御的堵塞网络。 如果类似的工程材料可以开发模仿这种行为，许多实际应用可能会导致，在更广泛的意义和影响的一节中指出，本摘要。项目的技术描述：本提案的研究目标是了解结构-性能力学的盲鳗防御凝胶和阐明这种理解的方式，这将使未来的工作设计具有新功能的生物启发的软材料。 我们的方法是开发超软材料的流变测量技术，通过使用线性和非线性流变学的惯性弹性振铃等技术，推动当前流变仪的实验极限。 通过这些技术，我们将测量各种盲鳗凝胶复合系统的流变学，这些系统具有不同的粘蛋白和丝组分的质量分数和比例，包括那些在自然界中没有发现的。 数学建模方法将从瞬态网络理论开始，该理论基于与可逆交联连接的应变硬化非线性弹性元件，该可逆交联在应力下减弱并提供应力软化。 然后，我们将通过与实验进行比较，改进和迭代数学模型来测试这些结构-性质假设。 这里开发的结构-性质关系将适用于盲鳗凝胶之外，并且一般包括基于聚合物和/或纤维组分的其他物理凝胶。 这将包括角蛋白细丝网络、胶原蛋白网络、粘蛋白凝胶网络和麸质网络，它们都显示出与用盲鳗凝胶观察到的类似的非线性流变行为。 更广泛的意义和重要性：八目鳗防御凝胶最初是一种体积很小的材料，然后经历剧烈的体积膨胀，产生一种超稀、超弹性的凝胶，阻止液体流过它。这种行为是目前工程材料无法比拟的。因此，这里的研究所形成的理解可能会带来可用于应用的材料的根本变化，包括但不限于：（i）石油钻井保障措施，用预先沉积在系统中或根据需要输送到系统的少量材料堵塞或减缓石油泄漏;（二）防御，通过在目的地运送一小包膨胀很大的材料，缠绕或堵塞发动机进气口、呼吸空气进气口或水冷进气口;（iii）细胞培养物，以提供纤维线元件的稀疏网络，其可以为组织支架和3D细胞培养物提供独特的结构和长度尺度，补充更小长度尺度和更致密的胶原纤维支架;（iv）利用解开线的新范例制造非织造材料，补充熔喷、熔纺和电纺工艺。八目鳗凝胶材料是独特的，但它的成分是普遍感兴趣的，因为它们是由许多其他软生物材料的构建块组成的。 扩大代表性不足的群体在工程中的参与：这项研究将被纳入教育和推广目标，这是鼓励多样性和代表性不足的群体在工程中的广泛参与。 这将通过流变动物园的发展来实现，这是一个实践性的流变学有趣材料库，将作为外展，参与和本科生研究机会的平台。 学生们将第一次看到看似简单的材料的非凡行为，了解这种行为在他们的日常生活中为何如此重要，并被鼓励创造性地思考软材料的新工程机会。动物园将成为为期六周的暑期项目的一部分，以帮助即将入学的学生过渡到大学，包括大量来自代表性不足的群体的学生。学生们将学习有趣的粘弹性材料从动物园，进行简单的测量，并提出他们的工作，以大学预科学生以外的大学，以进一步扩大接触和招聘工程。 学生项目将被整合到动物园，提供一个自我维持的机制，收集超出本提案的资金寿命。这项研究已通过工程招标，这是工程教育和中心司的工程计划的扩大参与的一部分，扩大参与研究启动赠款资助。

Background:Hagfish make a unique material with remarkable properties. When provoked or attacked, the animal releases a small volume of biopolymer/biofilament material that unfolds, assembles, and expands in water by a factor of 10,000. The resulting gel is cohesive, forming a clogging network used for defense. If analogous engineering materials could be developed to mimic this behavior, numerous practical applications could result, as noted in the Broader Significance and Impact section of this abstract.Technical description of the project:The research objective of this proposal to understand the structure-property mechanics of hagfish defense gel and to articulate this understanding in a way that will enable future work to design bioinspired soft materials with novel functionality. Our approach is to develop rheological measurement techniques for ultra-soft materials generally, pushing the experimental limits of current rheometers by using techniques such as inertio-elastic ringing for linear and nonlinear rheology. With these techniques we will measure the rheology of various hagfish gel composite systems with varying mass fractions and ratios of mucin and thread components, including those not found in nature. The mathematical modeling approach will start with transient network theory, based on strain-stiffening nonlinear elastic elements connected with reversible crosslinks that weaken under stress and provide stress-softening. We will then test these structure-property hypotheses by comparing with experiment, refining, and iterating the mathematical models. The structure-property relationships developed here will be applicable beyond hagfish gel, and generically include other physical gels based on polymeric and/or fibrous components. This would include keratin filament networks, collagen networks, mucin gel networks, and gluten networks, which have all displayed a similar nonlinear rheological behavior to that observed with the hagfish gel. Broader Significance and Importance:Hagfish defense gel starts as a small volume of material which then undergoes dramatic volumetric expansion, producing an ultra-dilute, super-elastic gel that blocks the flow of liquid through it. This behavior is unmatched by current engineering materials. The understanding developed by the research here could therefore bring about radical changes in materials available for applications including but not limited to (i) Oil-drilling safeguards, to plug or slow oil leaks with a small amount of material that is pre-deposited in the system or delivered to the system as needed; (ii) Defense, to tangle or clog engine intakes, respiratory air intakes, or water-cooling intakes by delivering a small packet of material with big expansion at destination; (iii) Cell cultures, to provide a sparse network of fibrous thread elements which may offer a unique architecture and lengthscale for tissue scaffolds and 3D cell cultures, complementing smaller lengthscale and denser collagen fiber scaffolds; (iv) Manufacturing non-woven materials with new paradigms of unraveling threads, complementing melt blowing, melt spinning, and electro-spinning processes. The hagfish gel material is unique, yet its components are of general interest, since they are composed of the building blocks of many other soft biological materials. Broadening Participation of Underrepresented Groups in Engineering:The research will be integrated into the educational and outreach objective, which is to encourage diversity and broad participation of underrepresented groups in engineering. This will be achieved through the development of The Rheology Zoo, a hands-on curated library of rheologically interesting materials that will serve as a platform for outreach, engagement, and undergraduate research opportunities. Students will, for the first time, see the remarkable behavior of seemingly simple materials, see how that behavior is so important in their daily lives, and be encouraged to think creatively about new engineering opportunities for soft materials. The Zoo will be a venue for part of a six-week summer program to help incoming students transition to college, including a large number of students from underrepresented groups. Students will study interesting viscoelastic materials from The Zoo, make simple measurements, and present their work to pre-college students outside the university to further broaden exposure and recruitment to engineering. Student projects will be integrated into The Zoo, providing a self-sustaining mechanism for the collection beyond the funding life of this proposal. This research has been funded through the Broadening Participation Research Initiation Grants in Engineering solicitation, which is part of the Broadening Participation in Engineering Program of the Engineering Education and Centers Division.