Self-Assembled Peptides for Electronic and Piezoelectric Applications

In recent years, a key direction in the field of electronics and electro-optics involves the transition from inorganic to organic components, thus paving the way towards flexible and wearable electronic devices. Bio-inspired organic materials may be the next-generation of organic optoelectronic devices, based on self-organization principles, which allow facile synthesis, eco-friendliness, resistance to oxidation and no need for heavy metal doping. Recent advances in bioorganic nanotechnology have established the notion that very simple building blocks, such as dipeptides, can form regular nanostructures with distinct mechanical, optical, piezoelectric and electronic properties. In particular, members of the diphenylalanine (FF) peptide archetypical family have been shown to form various morphologies and ordered nanostructures such as tubes, rods, fibrils, spheres, plates and macroscopic hydrogels with nano-scale order. These unique self-assembled peptide materials may be useful in the emerging field of implantable medical devices, which requires biocompatible power solutions to enable continuous and wireless operation.<br/>The abundant mechanical energy stored in our body, ranging from body motion, walking, breathing to internal movement of organs, heartbeats and blood pressure, can be converted into electrical energy by the piezoelectric effect to serve as an autonomic electrical source. Currently, the field of piezoelectric materials mainly relies on lead-based ceramic materials such as lead zirconate titanate (PZT). However, as lead is toxic and entirely non-biocompatible, there is an emerging need for alternative materials with strong piezoelectric performance, especially in the field of bio-applications. Piezoelectric bio-inspired materials have attracted significant attention in recent years as promising alternatives for currently used poisonous piezoelectric materials owing to their strong piezoelectricity along with their biocompatibility. Specifically, several studies have explored the piezoelectric properties of the FF peptide. Although significant progress has been made toward the functionalization of piezoelectric biomaterials, challenges in the formation of well-ordered nanostructures limit their application. Controlling the organization of such assemblies is a crucial milestone in engineering applicable piezoelectric materials since the magnitude of the piezoelectric response is dictated by the molecular organization at the nanoscale. Here, we demonstrate the functionalization of piezoelectric FF derivatives by nano-structural alignment. We have developed a custom-made measurement system for piezoelectric performance evaluation, calibrated using a commercially available piezoelectric material. Utilizing this system, we show the realization of self-assembled peptides as a promising piezoelectric alternative for bio-compatible energy solutions.