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

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.