Plasmon-enhanced Raman spectroscopy: Towards hyperuniform ultrasensitive enhancement through hyperuniform disorder

Abstract

We are developing a polymer-silver nanocomposite self-assembling-based protocol for fabricating surface-enhanced Raman scattering (SERS) substrates for versatile applications. The substrate is based on a silver-made fractal nanotexture produced by the long-range self-assembling of Ag-loaded block-copolymer micelles. We removed the nano-packing limitation imposed by the copolymer shell, achieving a condition close to the so-called hyperuniform structural disorder. Despite the large enhancement factor, estimated up to 109, the SERS response shows an ultrahigh spatial uniformity with a relative standard deviation in the range 0.9% - 5.6%, as measured from raster scans covering a total area of 1 cm2, that is from an active surface orders of magnitude larger than the typical nanofeature size and produced by an innovative low-cost and immediate deposition. The SERS-active coating allows large-scale spectroscopic scanning as required for real biological applications, still having, as experimentally evidenced, single-molecule sensitivity.