Gold nanoparticles (Au NPs) were synthesized by co-deposition of RF-sputtering and RF-PECVD from acetylene gas and Au target on the carbon nanotubes (CNTs). The CNTs were prepared by thermal chemical vapor deposition (TCVD) and Pd nanoparticles catalyst. TEM image shows that high-density and uniform distribution of Au NPs were grown on the CNTs. XRD analysis indicates that Au NPs have fcc crystal structure and CNTs have a good graphite structure. Raman spectroscopy results suggest that our sample includes double-walled CNTs. It is resulted that intensity of D-band reduces and G-band intensity raises and radial breathing mode (RBM) is changed by immobilizing of Au NPs on the CNTs. Raman results that the free electrons on the CNTs increase by immobilizing of Au NPs. Also localized surface plasmon resonance (LSPR) peak of Au NPs has red-shift and broadens when it is immobilized on the CNTs. The change in LSPR peak rises from decreasing of local electrons density on the Au NPs surface. Raman and ISAR spectroscopy suggest that there are charge transferring and chemical bonds between Au NPs and CNTs. We applied the prepared sensor chips of Au NPs@CNTs to detect DNA primer at femtomolar concentration based on the LSPR technique. (C) 2015 Published by Elsevier B.V.