Detection of an ssDNAtarget

For use as a target DNA (ssDNA_target), the 5′-CGTGCTTCAAAAAAGA-3′ oligonucleotide was dissolved in DIW. The melting temperature (T_m, the temperature at which 50% of the nucleotide is annealed) of the ssDNA_target to the ssDNA_probe was 44.1 °C. The ssDNA_target was injected onto the prepared TEM_DTAB/DNA biosensor at room temperature and then heated to the T_m. For analysis of sensitivity, different concentrations of the ssDNA_target (C_target = 0.05–10 nM) were tested. In order to test the specificity, ssDNA_target sequences of different mismatch degrees, such as completely mismatched 5′-AACGGGACTCGGGAGA-3′ (ssDNA_mm), 3-bp mismatched 5′-CGTGCTAGTTTTTTCT-3′ (ssDNA_3bpmm), and 2-bp mismatched 5-CGTGCTTCAAATTTCT-3′ (ssDNA_2bpmm), and dsDNA were tested.