Au nanoparticle-grafted hierarchical pillars array replicated from diatom as reliable SERS substrates

Surface-enhanced Raman spectroscopy (SERS) is to date a popular detection technology in chemistry, materials science, and medical research with growth potential to provide powerful sensing capabilities. However, there are still great challenges to design and fabricate reliable SERS substrate featuring good reproducibility and high sensitivity. Herein, we demonstrated a bio-templating approach to fabricate SERS substrate, using nanoimprint technique for replicating delicate hierarchical patterns of diatom frustules onto PDMS film, followed by sputtering Au nanoparticles. The minimum diameter and height of the nano-pillars on the substrate were similar to 40 nm and similar to 25 nm, respectively, which were identified with the dimensions of the nanopores on diatom frustules. The diameter and gap of the deposited Au nanoparticles could be changed by varying sputtering duration. The as-fabricated SERS substrate showed a high detection sensitivity (enhancement factor similar to 2.24 x 10(7)) with good Raman signal reproducibility for the probe molecule Rhodamine 6G (relative standard deviation of the intensity at 612 cm(-1) < 20%). More importantly, the limit of concentration (LOC) of the probe molecule reached as low as 10(-11) M. For extending the SERS substrate fabricated in this research to the potential applications including food safety, the SERS performance of Carbendazim was conducted and the LOC reached 10(-7) M.

Automated summary

This study demonstrated a bio-templating approach to fabricate a SERS substrate with high detection sensitivity and good reproducibility, showing promising performance for potential applications in various fields.