Controlling gold nanoparticle growth through peptide localization

The position of biomineralization peptides within liposomes can influence how gold nanoparticles grow, reports a research team from Institute of Science Tokyo. Peptides localized at the membrane interface promote branched structures, while those confined to the liposome interior favor spherical nanoparticles. The findings offer a new strategy for controlling nanoscale reaction environments in nanoparticle synthesis.

Gold nanoparticles possess unique optical and chemical properties owing to their size and shape. Thus, precise control over their growth is important for applications in sensing, catalysis, imaging, and other technologies. However, controlling where nucleation and growth occur during nanoparticle synthesis remains challenging, particularly under mild and environmentally friendly conditions. In such cases, biomineralization peptides—short chains of amino acids capable of promoting metal reduction and directing nanoparticle formation— offer a promising approach.

Nanoparticle growth is also influenced by the local reaction environment. In confined systems like liposomes, the membrane interface and internal aqueous compartment provide distinct environments, raising the question of whether biomineralization peptide positioning within these spaces could alter nanoparticle growth. To investigate this, a research team led by Associate Professor Masayoshi Tanaka from Institute of Science Tokyo (Science Tokyo), together with Graduate Student Yuya Abe from the Department of Chemical Science & Engineering, Science Tokyo and Professor Stephen D. Evans from the University of Leeds, developed liposomal nanoreactors containing biomineralization peptides. Their study, published in Advanced Functional Materials on August 18, 2026, demonstrates that peptide localization can help control gold nanoparticle growth.

To explore how peptide positioning affects nanoparticle growth, the researchers used liposomes as nanoscale reaction compartments and introduced a gold precursor, HAuCl₄. They first examined B3, a peptide known to both reduce gold ions and influence nanoparticle shape. When B3 was used, it predominantly localized near the liposome membrane, resulting in highly branched, anisotropic Au/liposome complexes. Transmission electron microscopy and elemental mapping revealed that gold was preferentially concentrated toward the periphery of these structures, indicating that nanoparticle growth occurred close to the membrane interface.

The researchers then changed the liposome composition by introducing the cationic lipid DOTAP. This shifted the B3 peptide toward the aqueous interior of the liposome, which was accompanied by the formation of spherical gold nanoparticles rather than highly branched structures. "By controlling where the peptide is positioned within the liposome, we can tune the nanoscale reaction environment in which gold nanoparticles grow," notes Tanaka.

The team also compared B3 with another biomineralization peptide, G1. In contrast, G1 remained predominantly localized within the aqueous interior, even after the membrane composition was changed. This led to the production of small, nearly spherical gold nanoparticles with an average diameter of about 2.7 nanometers. The comparison revealed that nanoparticle morphology depends not only on the peptide sequence itself but also on how the peptide is spatially organized within the confined reaction environment.

In the future, this study will provide a new design strategy for bio-inspired nanomaterials, in which peptide sequence and membrane composition can be used to control the spatial organization of reactions and steer nanoparticle growth toward structures with different properties and potential functions.

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About Institute of Science Tokyo (Science Tokyo)

Institute of Science Tokyo (Science Tokyo) was established on October 1, 2024, following the merger between Tokyo Medical and Dental University (TMDU) and Tokyo Institute of Technology (Tokyo Tech), with the mission of “Advancing science and human wellbeing to create value for and with society.”