Spacer‐free SERRS spectra of unperturbed porphyrin detected at 100 fM concentration in Ag hydrosols prepared by modified Tollens method

Surface‐enhanced resonance Raman scattering (SERRS) spectroscopy is a powerful tool for the selective and sensitive detection of porphyrins. We report a repeatable detection of unperturbed free base 5,10,15,20‐tetrakis(1‐methyl‐4‐pyridyl)21H,23H‐porphine in concentrations as low as 1 × 10–13 M in the final system when Ag nanoparticles prepared by modified Tollens method are employed as Raman scattering amplifiers, i.e. without any further post‐modifications of their surface. Most probably the residues of sugar oxidation present on Ag nanoparticle surface are responsible for the effective protection of 5,10,15,20‐tetrakis(1‐methyl‐4‐pyridyl)21H,23H‐porphine molecules against the metalation by silver.