**3.3 DNA/nucleic acid**

The sequence of nucleic acids for a precise detection was established in 1953 and is still developing widely [20]. These biosensors involve nucleic acids as a bio-recognition-prob. The high specific binding between the two single strands of DNA (ssDNA) sequences to make double stranded DNA (dsDNA) sequence is used to develop nucleic acids-based biosensor. This technique validated to develop DNA-built-biosensor from the old-style technique like pairing of radio iso-tropic and electrophoretic separations that are costly, dangerous, and time consuming.
