Direct laser writing of random Au nanoparticle three-dimensional structures for highly reproducible micro-SERS measurements

Abstract

Fabrication of freestanding, three-dimensional microstructures having gold nanoparticles as building blocks has been achieved using two-photon lithography. The reported constructions hold structural coherence without the need of a polymeric network to embed the nanoparticles. The Au nanoparticles are produced by radical-mediated photoreduction and immediately self-arrange in micrometre-sized cylinders, which are used as the building units of the 3D structure writing. The manufactured structures present plasmonic activity, as well as excellent properties as substrates for Surface-Enhanced Raman Spectroscopy, in key issues such as reproducibility in intensity or enhancement factor. Such is calculated to be above 8 × 10⁶ for the non-resonant probe molecule trans-1,2-bis-4-pyridylethylene. The option of repeated use of the substrates is confirmed, and they are successfully applied for detection of the fungicide thiabendazole.