Gold nanoparticles assembly on 1D, 2D and 3D microstructures

During the last decade, Metallic Nanoparticles (MNPs) attract much attention due to their localized surface plasmon resonance (1). Many considerable efforts have been put forth to align these NPs from colloidal solutions onto... [ view full abstract ]

During the last decade, Metallic Nanoparticles (MNPs) attract much attention due to their localized surface plasmon resonance (1). Many considerable efforts have been put forth to align these NPs from colloidal solutions onto patterned substrates in order to obtain extraordinary optical properties. To the date, patterning of plasmonic nanoparticles is an active challenge.(2)

In this context we will present a highly versatile approach to control the assembly of gold nanoparticles (GNPs) that present interesting optical properties in the visible region (figure 1). Our new approach is based on the functionalization of polymer micro and nanostructures by the inclusion of an amine molecule in a photopolymerizable mixture used for two-photon photolithography. After laser writing of any desired 1D, 2D and 3D microstructures, the obtained polymer templates are immersed in acetated GNP spheres for several hours resulting in the attachment of these nanoparticles on the polymer surface due to the high attraction towards the functionalized structures.

The linear arrangements of our GNPs can be as thin as 2-3 NPs wide for several microns of length, separated down to 400 nm (Figure 1-1D). Nanoparticle aggregation on the surface is rare even in relatively large surfaces: on Figure 1-2D, a 50×50 µm square is showing mainly a single layer arrangement. More interestingly, the colloidal solution can penetrate inside a complex 3D microstructure which can be completely covered by GNPs. In Figure 1-3D, the inclusion inside a woodpile photonic crystal of 20×20×8 µm with a period of 1 µm is shown. SERS and extinction spectra were performed on the GNPs patterns.

(1) Aroca, R., Surface-enhanced vibrational spectroscopy, John Wiley & Sons, Chiechester, 2006
(2) Su, B., et al., “A general strategy for assembling nanoparticles in one dimension”, Adv. Mater., Vol. 26, 2501-2507, 2014