Efficient silver-based hybrid nano-assemblies for polystyrene nanoparticles SERS detection

• Hybrids nano-assemblies made of 40 nm AgNCs decorated black Si nanostructures were built and used as SERS platforms for polystyrene nanoplastic beads detection; • High enhancement factors were obtained using Crystal violet as analyte molecule – EFs of 4.2 × 10 9 and 1.9 × 10 8 , for Si based nanotrees and nanopillars, respectively; • Efficient and stable SERS signals for PS nanoplastic were observed; • There were obtained LODs of 57.92 µg/ml, for the Si like nanotrees, and 21.43 µg/ml when using Si nanopillars substrate; Plastic materials are very important to our lives, with applications in different fields, but, their widespread use has resulted in huge amounts of plastic waste, released into the environment, affecting both, the wild and human life, becoming thus an environmental pollutant. Even Surface-Enhanced Raman Spectroscopy (SERS) was employed for years as analytical tool to identify plastic micro and nanoparticles, there is still work to be done, in order to develop efficient SERS platforms towards small concentrations of these nanomaterials types and to understand the involved enhancement mechanisms. This work proposes easily fabricated SERS substrates, based on two-hybrid nano-assemblies, made-off small silver nanocubes and black Si nanostructures, in order to improve the Raman signal for plastic molecules detection. Silicon nanostructures types – black Si nanotrees and nanopillars were obtained by the (Cryogenic) Deep Reaction Ion Etching method (DRIE), while the Ag nanocubes were synthesized using an eco-friendly route. Crystal violet was used as analyte molecule to evaluate the enhancement performances (EF) of the two fabricated platforms, being reported average values for the EFs of 4.2 × 10 9 and 1.9 × 10 8 , for Si based nanotrees and nanopillars, respectively. The applicability of the prepared SERS platforms was proven against polystyrene nanoparticles of 500 nm, the achieved LODs being of 57.92 µg/ml, for the Si like nanotrees, and 21.43 µg/ml when using Si nanopillars substrate. Herein, very good results were obtained for both substrates types, comparable with the ones reported by now, which confirm that our prepared platforms are efficient for SERS detection of different plastic nanomaterials.