Patent ID: 7419833

Claim:
A method for determining the sequence of a plurality of bases in a nucleic acid molecule, comprising: (a) providing a support surface bearing a nucleic acid molecule having a single stranded region; (b) exposing the nucleic acid molecule to four different base-specific nucleotides in the presence of an organic solvent, wherein each of the four different base-specific nucleotides comprises a different element having an atomic number greater than 25 and each element having an atomic number greater than 25 differs in atomic number from each other element having an atomic number greater than 25 by an atomic number of at least 15; (c) allowing the four different base-specific nucleotides to form base-pairs with bases in the single stranded region of the nucleic acid molecule; (d) removing at the non-base paired base-specific nucleotides by washing; (e) detecting the base paired nucleotides by electron microscopy; and (f) analyzing the detected base paired nucleotides to determine the sequence of a plurality of bases in the nucleic acid molecule.