Designing and fabricating of surface-enhanced Raman scattering substrate with high density hot spots by polyaniline template-assisted self-assembly

In general, the procedures for producing a high density hot spots structure should be stable, inexpensive, and easy to make. It still remains a grand challenge to assemble silver or gold nanoparticles (Au NPs) with well-defined hot spots for SERS detection. In this study, we present a very simple method for designing and fabricating a surface-enhanced Raman scattering (SERS) substrate with high density hot spots, using large area positively charged polyaniline (PANI) nanofibers as template to assemble negatively charged Au NPs. In order to obtain the optimized SERS-active substrates, different experiments to synthesize diverse Au/PANI with different sizes of Au NPs from about 50, 30 to 15 nm were carried out. The results revealed that the PANI nanofibers were fully coated by the ∼15 nm Au NPs, forming a high density Au/PANI SERS substrate. The results evidence that we can obtain stable and sensitive SERS measurements.