Design and fabrication of surface-enhanced Raman scattering substrate from DNA–gold nanoparticles assembly with 2–3 nm interparticle gap

Abstract

An ideal substrate for surface-enhanced Raman scattering (SERS) detection should induce a high signal enhancement and be easy to synthesize. Here, we showed that gold nanoparticles (Au NPs) were self-assembled onto DNA strands by electrostatic interactions and formed a well-defined DNA–Au hybrid structure with an interparticle gap of ca. 2–3 nm between two adjacent Au NPs, which could be used as active SERS substrates. Four different types of molecule, i.e. Rhodamine 6G, 4-aminothiophenol, pyridine and 2,4,6-trinitrotoluene, were studied on these substrates. All the detection limits for each analyte on the DNA–Au hybrid substrate were at least one order of magnitude higher than those on Au NPs alone without self-assembly on DNA. This phenomenon of assembly-induced signal enhancement has been experimentally and theoretically demonstrated in this study.