Synthesis of tailored nanostructured gold surfaces for SERS applications by controlled seed deposition and growth.

[Display omitted] • Full control of density and average distances on the deposition of metal nanoparticles on a surface. • Deposition and growth of engineered nanostructured gold surfaces. • Tailoring the gold nanostructured surface by design. • Realization of uniform SERS substrates with gold nanostructured surfaces and hormones' detection down to part-per-trillion. Surface-enhanced Raman spectroscopy (SERS) sensors are commonly based on metal nanoparticles in colloidal suspension followed by deposition on a substrate. Despite its simplicity, this approach leads to non-uniform SERS substrates that are hampered by features such as coffee rings. Seed-mediated growth starting from nanoparticles already deposited on a flat substrate potentially allows for creating more uniform and reliable sensors. However, the deposition process, the control of the distribution of the seed nanoparticles, and their optimal growth have not been thoroughly explored. In this work, we present a systematic approach to designing and fabricating gold nanostructured surfaces, tailoring their SERS responses on demand. By controlling and tuning the deposition of nanoparticles, assisted by an experimental and theoretical investigation, we achieved good control over the spatial distribution of the deposited seeds. After enlarging such seeds through chemical reduction, the optimized SERS substrates show great uniformity in their hotspots, a critical feature for sensors. The so-fabricated substrates were used for detecting Skatole in water, achieving a detection limit of 42.2 ppt. The developed methodology has significant implications for the advancement of several fields, particularly SERS-based sensing, enabling the design and targeting of specific excitation wavelengths and Raman bands while obtaining uniform and reliable substrates. [ABSTRACT FROM AUTHOR]