title: Ultrahigh-density array of silver nanoclusters for SERS substrate with high sensitivity and excellent reproducibility.
abstract: We introduce a simple but robust method to fabricate an ultrahigh-density array of silver nanoclusters for a surface-enhanced Raman spectroscopy (SERS) substrate with high sensitivity and excellent reproducibility at a very large area (wafer scale) based on polystyrene-block-poly(4-vinylpyridine) copolymer (PS-b-P4VP) micelles. After silver nitrates were incorporated into the micelle cores (P4VP) followed by the reduction to silver nanoclusters, we systematically controlled the gap distance between two neighboring silver nanoclusters ranging from 8 to 61 nm, while the diameter of each silver nanocluster was kept nearly constant (~25 nm). To make a silver nanocluster array with a gap distance of 8 nm, the use of crew-cut-type micelles is required. Fabricated SERS substrate with a gap distance of 8 nm showed very high signal intensity with a SERS enhancement factor as high as 10(8), which is enough to detect a single molecule, and excellent reproducibility (less than ±5%) of the signal intensity. This is because of the uniform size and gap distance of silver nanoclusters in a large area. The substrate could also be used for label-free immunoassays, biosensing, and nanoscale optical antennas and light sources.
authors: National Creative Research Initiative Center for Block Copolymer Self-Assembly, Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk 790-784, Korea.
authors: Won Joon
authors: WJ
authors: Cho
authors: Youngsuk
authors: Y
authors: Kim
authors: Jin Kon
authors: JK
authors: Kim
mesh_terms: D003460:Crystallization / Q000379:methods; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D012680:Sensitivity and Specificity; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D012834:Silver