Fluorescent Proteins as Reporters of Mechanically Induced Damage in Fiber-Reinforced Composites

Self-reporting materials based on the force-induced modulation fluorescence of proteins in polymeric materials

Mechanical forces and mechanical stimuli are an inherent part of nature, but their effect in controlling biochemical events has only recently been addressed in detail. Mechanobiochemistry is not only of relevance to understand processes in living systems, but it can also be a source of inspiration for the molecular design of novel materials with advanced properties. We have pioneered the force-induced modulation of photophysical properties of fluorescent proteins in polymeric materials in order to create materials that can self-report damage. For example, fluorescent proteins were conjugated onto glass and carbon fibers. These fibers were embedded into epoxy resin. The resulting fiber-reinforced composites could detect low velocity impact damage by a loss of fluorescent at the damage site. This allowed to visualize micron-scale damage such as fiber fractures and debonding at the interface of fibers and polymer matrix. The self-reporting system could find application as safety feature to detect barely visible impact damage in load-bearing composites or as analytical tool to monitor and characterize microscopic damage propagation in composites. Conceptually, the results demonstrate that mechanical forces can be transduced from materials to proteins if the proteins reside at an interface within the material, thus allowing to harness mechanically induced biochemical responses in a materials context.  

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