Facile synthesis of multibranched gold nanostars with precisely tunable sizes for surface-enhanced Raman scattering

The anisotropic morphology of metal nanomaterials with a rough surface is well-known to play an important role in surface-enhanced Raman scattering (SERS) and catalysis. In this work, a facile synthesis of multibranched Au nanostars with controllable shapes and tunable sizes was achieved in the presence of cysteine via a seed-mediated growth method. The effects of reaction parameters (such as cysteine, seed, gold precursor, AA and surfactant concentrations) on product morphology and size were systematically investigated by tracking the growth process and recording the morphological evolution process. Meanwhile, using 4-ATP as a Raman reporter, the Au nanostar substrate exhibits superior SERS characteristics, and can effectively detect the 4-ATP analyte at concentrations as low as 1 × 10−11 M. Moreover, the SERS substrate exhibits good Raman signal uniformity and reproducibility. This study opens up a new avenue for the synthesis of multibranched Au nanostructures, enabling promising applications in the fields of SERS detection, sensing and imaging.