Decrease of carbon nanotube UV light absorption induced by π-π-stacking interaction with nucleotide bases

摘要

UV-vis absorption spectra of hybrids formed by carbon single-walled nanotubes (SWCNTs) and single-stranded DNA (ss-DNA), double-stranded DNA (ds-DNA), and synthetic homo-polynucleotides (poly(rC) and poly(rG)) have been studied. In the 300-400 nm spectral range a decrease of SWCNT light absorption because of their interaction with polymers was observed. The revealed decrease of nanotube absorption is explained by SWCNT hypochro-mism that results from π-π-stacking interaction of polymer nitrogen bases with the tube surface. Molecular dynamic simulation demonstrates a spontaneous wrapping of polynucleotides around the nanotube. Simulation showed that pyrimidine oligonucleotide (d(C)_(25)) manifests a higher rate of minimizing the hybrid structure with the wrapped polymer structure around the tube than the purine one (d(G)_(25)). Such polymer behavior can be explained by the purine oligonucleotide property to form a stable ordering self-stacking structure which prevents structural re-orientation, in contrast to pyrimidine polynucleotides.