A research team from the Institute of Physics, Chinese Academy of Sciences has developed a novel DNA origami-based technique to synthesize stable, monolithic amorphous silver nanostructures under ambient conditions. By using DNA scaffold with fivefold rotational symmetry, the method introduces geometric frustration that effectively suppresses crystallization in metallic silver, a traditionally challenging feat due to the natural tendency of silver to form crystalline structures. Detailed characterization and molecular dynamics simulations demonstrate that these amorphous silver domains exhibit high stability and disordered atomic arrangements, opening new avenues for innovative applications in electronics, catalysis, and plasmonics.
Single-element amorphous metals, or metallic glass, are considered an ideal model systems for studying atomic-scale amorphous and glass formation. Moreover, their unique physical and chemical properties, such as high strength, corrosion resistance and distinctive optical properties, make them very attractive for industrial processes. However, conventional synthesis of monatomic amorphous metals remains a challenge due to their intrinsic tendency to form crystals. Traditional methods, including rapid quenching, laser melting, or vapor deposition at cryogenic temperatures, demand complex equipment and extreme processing conditions, often resulting in unstable or partial amorphous phases. These limitations hinder the development of pure, stable monometallic amorphous structures, especially at ambient conditions, constraining fundamental understanding and practical use. Furthermore, existing approaches lack precise control over nanoscale morphology and atomic arrangement, limiting their applicability in device engineering. Achieving stable, atomically disordered monometallic phases under ambient conditions remains a significant scientific challenge.
To solve this limitation, a research team introduced a novel DNA origami-based bottom-up fabrication strategy designed to circumvent these longstanding limitations. By engineering a pentagonal DNA scaffold exhibiting near-fivefold rotational symmetry, the researchers establish a confined microenvironment that naturally induces geometric frustration, an incompatible condition for crystalline order in metals like silver. This geometric constraint effectively limits the long-range atomic alignment necessary for crystallization. The process involves the electrostatic adsorption of silver ions onto the negatively charged DNA scaffold, followed by a controlled reduction that deposits silver atoms confined within the scaffold's nanoscopic cavity. High-resolution microscopy reveals that, unlike crystalline silver, the resulting structures are predominantly amorphous, with a disordered atomic arrangement sustained even under extended electron beam irradiation tests. Complementary molecular dynamics simulations shed light on the role of fivefold symmetry, showing it increases local structural entropy and hinders atomic diffusion and rearrangement necessary for crystallization.
Fabrication
