Facile and scalable preparation of solution-processed succulent-like silver nanoflowers for 3D flexible nanocellulose-based SERS sensors

The synthesis of three-dimensional (3D) silver nanostructures with prominent plasmonic characteristics is of great importance in surface-enhanced Raman scattering (SERS) sensing applications. However, the preparation of 3D Ag nanostructures often suffer from high cost, complicated operation steps, time-consuming process and special instruments. In this work, 3D succulent-like silver nanoflowers (S-AgNFs) are successfully synthesized by a simple, scalable and low-cost liquid-phase reduction method at room temperature. The S-AgNFs with a diameter that ranges from 500 to 800 nm are composed of nano-petals that are about 60 nm in thickness. The growth process of S-AgNFs is systematically observed and investigated. And the solution-processed S-AgNFs are served as flexible SERS sensors via facile vacuum-assisted filtration onto bacterial nanocellulose (BNC) membranes. Attributed to unique 3D nanostructures of S-AgNFs, the as-prepared S-AgNFs@BNC SERS sensor with high-density and multi-level hotspots exhibits ultra-high detection sensitivity of 10−13 M for malachite green (MG), impressive enhancement factor of 1.2 × 1010, good signal reproducibility and remarkable stability. Moreover, the flexible S-AgNFs@BNC SERS sensor also demonstrates excellent detection sensitivity of 10−10 M for detecting pesticide residues on irregular surfaces. The flexible, stable and ultrasensitive S-AgNFs@BNC SERS sensor is promising for application in rapid identification of hazardous molecules, bacteria and viruses.