Effective Hotspot Arrays Based on Non-Close-Packed Gold Nanoshells in Microporous Polystyrene Film on Acupuncture Needles

To constructing effective hotspot arrays in SERS substrates, gold nanoshells (GNSs) were assembled layer by layer on acupuncture needles by covalent absorption of bifunctional chemicals; three dimensional structures of the GNSs were locked by polystyrene (PS) coating; effective hotspots were obtained by removing bifunctional chemicals on surface of the GNSs, and the spacing between GNSs was enlarged by corroding gold shell layers of the GNSs partly. The strongest SERS signal was obtained from the SERS-active substrate with two-layer GNSs. After effective hotspot arrays were constructed in the SERS-active substrate with two-layer GNSs, its enhancement factor was higher about two to three orders of magnitude than that of the monolayer of close-packed GNSs. The hotspot arrays integrated on acupuncture needles would be used to detect low concentration of biomolecules in vivo.