| Surface enhanced Raman scattering (SERS) from N-substituted 2,4-dinitrophenyl (DNP)-amino acids adsorbed on colloidal silver has been observed. SERS spectra of DNP-methionine, DNP-cystine, DNP-aspartic acid, and ;Transmission electron micrographs indicated that the aggregation of the silver particles with adsorbed DNP-amino acid was a slow process, beginning as single particles which form linear chains and then cluster together to form open low density aggregates. These aggregates are of fractal quality and fractal dimensions were calculated as 1.23(9), 1.29(10), and 1.35(7), similar to those derived theoretically for linear polymer chains.;Addition of IgE anti-DNP antibody to the DNP-amino acid-colloidal silver system, showed no evidence of further aggregation through agglutination of the antibody-bound hapten due to preferential binding to the DNP-amino acid in solution. |
