Application of surface-enhanced Raman scattering spectroscopy to the study of insect virus virion

The Surface-Enhanced Raman Scattering (SERS) spectra of the virions of four kinds of insect virus: Nuclear polyhedrosis virus of Trabala Vishnou (TvNPV), Nuclear polyhedrosis virus of Gynaephora ruoergensis (GrNPV), Granulosis Virus of preris rapae (PrGV) and Granulosis Virus of Dama trima (DtGV) adsorbed on the surface of silver colloid particles have been obtained and investigated. The strong interactions appeared between silver surface and COO- groups, NH2, groups or aromatic side-chains in SERS of the molecules of the virions. The intensities of bands related to the vibrations of COO- groups are 458-460cm(-1): v( COO-), 568 similar to 577cm(-1): w(COO-), 614 similar to 624cm(-1): delta( COO-), 914 similar to 934cm(-1): v( C-COO-) and the bands related to the vibrations of NH2 groups are 1114 similar to 1134cm(-1): t(NH2), 1620 similar to 1632cm(-1): delta (NH2), 3390 similar to 3398cm(-1): v(NH2). It indicates that the molecules of the virions adsorbed on silver through both the COO. and NH,groups. The short-range enhancement results from a chemical interaction between the virion molecules and the silver surface. The bands at low frequency (218-236 cm(-1)) in the SERS spectra of the four samples show that chemiscorption is a main mechanism on silver hydrosis of the virion. The pi - electron systems of side-chains of the aromatic amino acids in virion have formed the additional adsorption centers in the molecules of virions, it will decrease the distance between some groups of molecules and the silver surface. So the bands at 928 , 914 , 930 , 934 cm(-1), due to the skeletal C-C vibration, have been enhanced.