A colorimetric inhibition study of single-stranded DNA decamer sequence interactions with dinitrotoluene

A novel colored reaction between 2,4-dinitrotoluene (DNT) and dimethylsulfoxide (DMSO) on carbonate-activated plastic surfaces is described. In a preliminary study of the potential of oligonucleotides to bind nitroaromatic explosives, a random library of 1,040 single stranded (ss) DNA decamers (10 bases) in polystyrene microtitre plates were screened for inhibition of color development. The vast majority (89%) of sequences in the library completely inhibited color formation, suggesting that hydrogen bonding between DNA and the nitro groups of DNT was the predominate attractive force. Of the 114 sequences which allowed some visible color development, absorbance (405 nm) values were negatively correlated with GC content (r = -0.764), suggesting that some specific binding "pocket" structures for DNT may exist in the small library examined. Among the color evolving combinations, differences in amount of DNA were not correlated with absorbance.