Microarray based Raman spectroscopic detection with gold nanoparticle probes

A microarray approach based on surface-enhanced Raman spectroscopic (SERS) was developed for detection of spotted peptide, peptide–protein or protein–antibody interaction. The procedure involves the attachment of peptide-capped gold nanoparticles followed by silver deposition for signal enhancement. The attachment of the gold nanoparticles is achieved by standard avidin–biotin chemistry. The well-known biomolecular recognition pairs, IgG/protein A and biotin/avidin, were used to demonstrate proof-of-concept of the SERS assay. Detection limits of 10 and 100 fg per microarray spot were obtained respectively for the peptide and protein arrays. For the protein in solution, a limit of 0.1 μg/mL is reported. Furthermore, enzyme activity of the kinase (PKA) is also detected with high specificity for an established peptide substrate (kemptide) on the microarray spots.