DNA-templated method opens new frontiers in synthesizing amorphous silver nanostructures

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

The growing start first by introducing a small amount of Cu²⁺ ions into the DNA solution, where they coordinated with the DNA scaffold and served as nucleation seeds. These Cu²⁺ ions were subsequently reduced in situ to metallic Cu⁰ using ascorbic acid. The system was then supplied with higher concentrations of Ag⁺ and Cu²⁺ ions together with the reducing agent, allowing a galvanic replacement reaction to occur in situ, during which the Cu⁰ seeds were spontaneously replaced by Ag⁰. As a result, silver was deposited and grew in a spatially confined manner along the pentagonal DNA framework, yielding silver nanostructures distributed on the DNA template (NP-Ag@DNA) and exhibiting a well-defined and stable fivefold-symmetric morphology.

Comparative experiments were conducted to clarify the role of the DNA origami template in silver nucleation and growth by synthesizing silver nanostructures in the absence (NP-Ag) and presence (NP-Ag@DNA) of the template. Without DNA, silver nanoparticles formed columnar polycrystalline structures with aligned crystallites, exhibiting pronounced long-range order. In contrast, DNA-templated samples displayed markedly altered morphologies and internal structures, including polygonal or near-spherical particles with increased atomic disorder. Notably, a fully amorphous silver domain (~3 nm) was consistently observed at the center of the DNA origami template. Electron-beam irradiation experiments demonstrated that this amorphous domain remains structurally stable under prolonged irradiation, showing no evidence of recrystallization. Molecular dynamics simulations further revealed that crystallization kinetics are highly sensitive to boundary symmetry: whereas amorphous regions rapidly crystallize under zero or low-order symmetries, fivefold-symmetric confinement significantly delays recrystallization by increasing local structural diversity and structural information entropy. Together, these results establish near-fivefold geometric confinement as an effective mechanism for stabilizing amorphous silver at the nanoscale.

The Future: This work demonstrates the controllable synthesis of monometallic amorphous nanostructures under ambient pressure and at room temperature via DNA-templated self-assembly, providing direct evidence that geometric symmetry design plays a decisive role in suppressing crystallization. In contrast to conventional amorphization strategies that rely on extreme cooling rates, the fivefold-symmetric DNA origami confinement enables effective inhibition of crystalline ordering under mild conditions, thereby establishing a new route for the fabrication of single-element amorphous metals. By integrating programmable biomolecular templates, chemical reduction-deposition processes, and nanoscale spatial confinement, this approach affords precise control over silver nucleation and assembly. The resulting amorphous silver nanostructures constitute a well-defined and reproducible model system for investigating the mechanisms of metallic glass formation. More broadly, this DNA-templated amorphization strategy is expected to be generalizable to other crystallization-prone face-centered cubic metals, such as Au, Cu, and Pd, offering new opportunities to access metastable amorphous phases in single-element systems. Future studies may incorporate in situ characterization techniques to directly track atomic-scale structural evolution under DNA confinement, enabling deeper insight into the relationship between boundary symmetry and amorphous stability.

The Impact: The development of three-dimensional DNA origami confinement or hierarchical assembly of amorphous silver building blocks may open pathways toward constructing metallic glass materials at larger length scales.

The research has been recently published in the online edition of Materials Futures, a prominent international journal in the field of interdisciplinary materials science research.

Reference:  Ziyuan Cheng, Weiguang Lin, Yitao Sun, Jun Li, Dongdong Xiao, Laiquan Shen, Zhen Lu, Weihua Wang. DNA-templated synthesis of amorphous silver nanostructures via fivefold-symmetry-induced crystallization suppression[J]. Materials Futures, 2026, 5(1): 015002. DOI: 10.1088/2752-5724/ae3098