Interaction of nucleic acids with graphite powder and SWCNT was studied by surface enhanced infrared absorption spectroscopy. The analysis of DNA-SWCNT complex vibrational modes shows that the numerous structural changes in DNA are connected to appearance of new sugar and bases conformations, changes in phosphate vibrations, which may be interpreted as A-B conformation transition and stabilisation of structure in some DNA fragments. A slight graphite influence on the DNA structure has been registered. The spectroscopic data could be explained by the model of DNA interaction with SWCNT based on wrapping of nucleic acid molecules around carbon nanotubes proposed by R. Smalley. A similar situation seems to occur in chromosome during DNA assembling by histones. (C) 2003 Elsevier Science B.V. All rights reserved.