Surface-enhanced Raman scattering studies on the recognition mechanism of glutathione peroxidase mimics, bis-cyclodextrin diselenide

Surface-enhanced Raman scattering (SERS) spectroscopy has been used to explore the recognition mechanism between a selenium-containing glutathione peroxidase (GPX) mimic, 2,2′-diseleno-bis-β-cyclodextrin (2-SeCD) and two glutathione (GSH) alternatives, S-dinitrophenyl-glutathione (GSH-S-DNP) and 4,4′-bis(carboxymethyleneoxy)azobenzene (BCMAB). SERS spectra have been employed to investigate how these alternatives bind with β-CD and 2-SeCD. SERS signals of the spectra of GSH-S-DNP and BCMAB are much intense in comparison with those of theirs complexes, GSH-S-DNP/CDs and BCMAB/CDs in silver colloid solutions, which suggest that GSH-S-DNP and BCMAB are included into the CD cavity when they bind with β-CD or 2-SeCD. Weak Raman signals in the SERS spectra of the GSH-S-DNP/CDs in silver colloid solution make it difficult to investigate the recognition mechanism between CDs and GSH-S-DNP by using SERS efficiently. The bands at 1388 and 1379 cm−1 in the SERS spectra of BCMAB/CDs strongly suggest that BCMAB does not bind with β-CD or 2-SeCD via its COOH group.