Positively charged silver nanoparticles and their effect on surface-enhanced Raman scattering of dye-labelled oligonucleotides

Improved positively charged nanoparticles are described to provide a simplified SERS substrate for DNA detection. Complete flocculation of the nanoparticles is prevented due to the controlled analyte induced aggregation. This provides a stable aggregation state which significantly extends the analysis window simplifying DNA detection by SERS.