Apparatus and methods to identify nucleotides of a DNA strand. The method includes exposing the DNA strand to a first dye or peptide, attaching the first dye or peptide to a first type of nucleotide (A,T,C,G) of the DNA strand, the first dye or peptide changing a conductance of the first type of nucleotide to which the first dye or peptide is attached, and measuring a tunneling current signal for all nucleotides of the DNA strand, the changed conductance of the first type of nucleotide providing amplified tunneling current discrimination of the nucleotides of the DNA strand.