Silver nanoparticles as surface-enhanced Raman substrate for quantitative identification of label-free proteins

We developed a novel method to fabricate uniformly distributed silver nanoparticles (AgNPs) on nanostructured polymer for use as surface-enhanced Raman spectroscopy (SERS) substrates. Over 92% reproducibility on the same substrate was obtained in SERS analyses of benzenethiol (BT) using this novel substrate. The reproducibility of the BT SERS spectra collected from different substrates is >82%. The new SERS substrates were further used to quantitatively analyze label-free dipeptide in aqueous solution. The Raman signal is reproducible with levels above 91% for solution concentrations from 1 μg ml−1 to 1 ng ml−1 of the label-free dipeptide. The accurate and reproducible identification over a wide concentration range demonstrated that the new SERS substrate is suited for use in quantitative identification of biomolecules.