DigitalCommons@Linfield

Surface-Enhanced Raman Scattering of Invertase on Silver Nanoparticles

Jereld R. Nicholson Library

Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive technique to characterize molecules. Proteins have been a key substrate in recent studies with SERS because of their ability to bind strongly and distinctively to other molecules. In this study, the SERS spectrum of β-fructofuranosidase (invertase) was characterized on silver colloids and silver nanoparticle surfaces. Aromatic amino acid and cystine vibrations dominate the SERS spectrum of most proteins, including invertase. Specifically peaks at 812 (tyr), 962 (trp, tyr), 1092 (trp W14, tyr), 1159 (trp W12), 1294 (tyr), 1327 (trp, tyr), 1555 (tyr, trp W3), and 1613 (phe F8a, tyr Y8a, trp W1) cm^-1 were characterized. The peaks observed show in-plane ring vibrations, indicating the rings are perpendicular to the silver surfaces. In addition, an observation of one amide III vibration at 1294 cm^-1 in solution SERS and two amide III vibrations at 1286 and 1570 cm^-1 were found on the metal films; these findings signify a portion of invertase that is interacting with the silver surface is alpha helical. When comparing the different surfaces, it is shown that the interacting portion of invertase changes when the surface changes.