skip to main content

Title: Biomimetic and bioinspired molecular electrets. How to make them and why does the established peptide chemistry not always work?
Abstract “Biomimetic” and “bioinspired” define different aspects of the impacts that biology exerts on science and engineering. Biomimicking improves the understanding of how living systems work, and builds tools for bioinspired endeavors. Biological inspiration takes ideas from biology and implements them in unorthodox manners, exceeding what nature offers. Molecular electrets, i.e. systems with ordered electric dipoles, are key for advancing charge-transfer (CT) science and engineering. Protein helices and their biomimetic analogues, based on synthetic polypeptides, are the best-known molecular electrets. The inability of native polypeptide backbones to efficiently mediate long-range CT, however, limits their utility. Bioinspired molecular electrets based on anthranilamides can overcome the limitations of their biological and biomimetic counterparts. Polypeptide helices are easy to synthesize using established automated protocols. These protocols, however, fail to produce even short anthranilamide oligomers. For making anthranilamides, the residues are introduced as their nitrobenzoic-acid derivatives, and the oligomers are built from their C- to their N-termini via amide-coupling and nitro-reduction steps. The stringent requirements for these reduction and coupling steps pose non-trivial challenges, such as high selectivity, quantitative yields, and fast completion under mild conditions. Addressing these challenges will provide access to bioinspired molecular electrets essential for organic electronics and energy conversion.  more » « less
Award ID(s):
Author(s) / Creator(s):
; ; ; ; ; ;
Date Published:
Journal Name:
Pure and Applied Chemistry
Page Range / eLocation ID:
275 to 299
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. null (Ed.)
    Biological structure-function relationships offer incomparable paradigms for charge-transfer (CT) science and its implementation in solar-energy engineering, organic electronics, and photonics. Electrets are systems with co-directionally oriented electric dopes with immense importance for CT science, and bioinspired molecular electrets are polyamides of anthranilic-acid derivatives with designs originating from natural biomolecular motifs. This publication focuses on the synthesis of molecular electrets with ether substituents. As important as ether electret residues are for transferring holes under relatively high potentials, the synthesis of their precursors presents formidable challenges. Each residue in the molecular electrets is introduced as its 2-nitrobenzoic acid (NBA) derivative. Hence, robust and scalable synthesis of ether derivatives of NBA is essential for making such hole-transfer molecular electrets. Purdie-Irvine alkylation, using silver oxide, produces with 90% yield the esters of the NBA building block for iso-butyl ether electrets. It warrants additional ester hydrolysis for obtaining the desired NBA precursor. Conversely, Williamson etherification selectively produces the same free-acid ether derivative in one-pot reaction, but a 40% yield. The high yields of Purdie-Irvine alkylation and the selectivity of the Williamson etherification provide important guidelines for synthesizing building blocks for bioinspired molecular electrets and a wide range of other complex ether conjugates. 
    more » « less
  2. null (Ed.)
    Abstract Biomimicry, biomimesis and bioinspiration define distinctly different approaches for deepening the understanding of how living systems work and employing this knowledge to meet pressing demands in engineering. Biomimicry involves shear imitation of biological structures that most often do not reproduce the functionality that they have while in the living organisms. Biomimesis aims at reproduction of biological structure-function relationships and advances our knowledge of how different components of complex living systems work. Bioinspiration employs this knowledge in abiotic manners that are optimal for targeted applications. This article introduces and reviews these concepts in a global historic perspective. Representative examples from charge-transfer science and solar-energy engineering illustrate the evolution from biomimetic to bioinspired approaches and show their importance. Bioinspired molecular electrets, aiming at exploration of dipole effects on charge transfer, demonstrate the pintail impacts of biological inspiration that reach beyond its high utilitarian values. The abiotic character of bioinspiration opens doors for the emergence of unprecedented properties and phenomena, beyond what nature can offer. 
    more » « less
  3. Artificially designed molecular systems with programmable behaviors have become a valuable tool in chemistry, biology, material science, and medicine. Although information processing in biological regulatory pathways is remarkably robust to error, it remains a challenge to design molecular systems that are similarly robust. With functionality determined entirely by secondary structure of DNA, strand displacement has emerged as a uniquely versatile building block for cell-free biochemical networks. Here, we experimentally investigate a design principle to reduce undesired triggering in the absence of input (leak), a side reaction that critically reduces sensitivity and disrupts the behavior of strand displacement cascades. Inspired by error correction methods exploiting redundancy in electrical engineering, we ensure a higher-energy penalty to leak via logical redundancy. Our design strategy is, in principle, capable of reducing leak to arbitrarily low levels, and we experimentally test two levels of leak reduction for a core “translator” component that converts a signal of one sequence into that of another. We show that the leak was not measurable in the high-redundancy scheme, even for concentrations that are up to 100 times larger than typical. Beyond a single translator, we constructed a fast and low-leak translator cascade of nine strand displacement steps and a logic OR gate circuit consisting of 10 translators, showing that our design principle can be used to effectively reduce leak in more complex chemical systems. 
    more » « less
  4. Synopsis

    Bioinspired design (BID) is an interdisciplinary research field that can lead to innovations to solve technical problems. There have been many attempts to develop a framework to de-silo engineering and biology and implement processes to enable BID. In January of 2022, we organized a symposium at the 2022 Society of Integrative and Comparative Biology Annual Meeting to bring together educators and practitioners of BID. The symposium aimed to (a) consolidate best practices in teaching bioinspiration, (b) create and sustain effective multidisciplinary teams, (c) summarize best approaches to conduct problem-based or solution-driven fundamental research, and (d) bring BID innovations to market. During the symposium, several themes emerged. Here we highlight three critical themes that need to be addressed for BID to become a truly interdisciplinary strategy that benefits all stakeholders and results in innovation. First, there is a need for a usable methodology that leads to proper abstraction of biological principles for engineering design. Second, the utilization of engineering models to test biological hypotheses is essential for the continued engagement of biologists in BID. Third, there is a necessity of proven team-science strategies that will lead to successful collaborations between engineers and biologists. Accompanying this introduction is a variety of perspectives and research articles highlighting best practices in BID research and product development and guides that can highlight the challenges and facilitate interdisciplinary collaborations in the field of BID.

    more » « less
  5. Charge transfer and charge transport are by far among the most important processes for sustaining life on Earth and for making our modern ways of living possible. Involving multiple electron-transfer steps, photosynthesis and cellular respiration have been principally responsible for managing the energy flow in the biosphere of our planet since the Great Oxygen Event. It is impossible to imagine living organisms without charge transport mediated by ion channels, or electron and proton transfer mediated by redox enzymes. Concurrently, transfer and transport of electrons and holes drive the functionalities of electronic and photonic devices that are intricate for our lives. While fueling advances in engineering, charge-transfer science has established itself as an important independent field, originating from physical chemistry and chemical physics, focussing on paradigms from biology, and gaining momentum from solar-energy research. Here, we review the fundamental concepts of charge transfer, and outline its core role in a broad range of unrelated fields, such as medicine, environmental science, electronics and photonics. The ubiquitous nature of dipoles, for example, sets demands on deepening the understanding of how they affect charge transfer. Charge-transfer electrets, thus, prove important for advancing the field and for interfacing fundamental science with engineering. Synergy between the vastly different aspects of charge-transfer science sets the stage for the broad global impacts that the advances in this field have. 
    more » « less