Designing atomically precise gold nanocluster architectures with DNA-guided self-assembly and biofunctionalization approaches

Atomically precise gold nanoclusters (AuNCs) are nanomolecular species with unique optoelectronic properties, both at the individual and assembled levels. Herein, we demonstrate the precise ligand engineering of AuNCs, enabling the controlled grafting of single-stranded oligonucleotides onto atomically defined AuNCs of different sizes-Au₁₈ and Au₂₅-which emit in the NIR-I (600-800 nm) and NIR-II (900-1300 nm) spectral windows, respectively. These biofunctionalized AuNCs, which can be considered nanomolecular building blocks, were thoroughly characterized using complementary analytical and optical techniques, including absorption and fluorescence spectroscopy, mass spectrometry, liquid chromatography, and gel electrophoresis. Through selective DNA hybridization, we successfully assembled AuNC dimers, trimers, and AuNC-dye nanosystems with high reproducibilities and yields. This work lays the foundation for the design of AuNC-DNA superstructures with potential applications in optoelectronics, sensing, and nanomedicine.