Sequence-specific recognition of single-stranded DNA using atomic absorption spectrometry
A method for the sequence-specific recognition of single-stranded DNA using atomic absorption spectrometry has been developed based on the use of gold nanoparticle (AuNP) and silver-coated glass modified with oligonucleotides. Silver-coated glass modified with the oligonucleotide 5′-SH-T10-TCT CTC CCA GGA CAG G-3′ (Oligo 1) was used as the separation material and AuNP modified with oligonucleotide 5′-CAC AAA CAC GCA CCT C-T10-HS-3′ (AuNP-Oligo 2) acted as the signal-reporting component. When the target DNA (5′-GAG GTG CGT GTT TGT GCC TGT CCT GGG AGA GA-3′) was added, it hybridized with Oligo 1 on the surface of the silver-coated glass and with Oligo 2 on the surface of the AuNP. The concentration of the target DNA was represented by the number of AuNP bound to the surface of the silver-coated glass and could therefore be determined using atomic absorption spectrometry. The integrated absorbance was proportional to the concentration of the target DNA over the range 10.0–200 nM with a limit of detection of 0.23 nM (3σ/slope). The sensitivity of the assay was further improved by using a layer-by-layer technique. All the processes were characterized using scanning electron microscopy, the water contact angle and X-ray photoelectron spectroscopy.