Amplified oligonucleotide sensing in microliter volumes containing copper ions by solution streaming
We present a simple, cost-effective design for amplifying oligodeoxynucleotide (ODN) sensing, in microliter ODN volumes containing copper ions, by solution streaming ( bubbling). The inert gas streaming ( bubbling) at a constant pressure of 0.04 bar drives the motion of a 30-mu L ODN droplet containing a three-electrode circuit ( inverted drop microcell), and in the presence of copper ions offers an similar to 50-times improvement in the detection of ODN samples. The detection of ODNs at the carbon paste electrode is based on the enhancement of the oxidation peaks of purine bases ( adenine and guanine) by the anodic stripping of the electrochemically accumulated complex of Cu(I) with purine base residues of acid hydrolyzed ODN samples ( Cu(I)-ahODN complex). We used the proposed method for (i) the determination of the percentage content of adenine and guanine units within analyzed ODN samples at subnanomolar concentrations ( related to monomer content) and (ii) the detection of the (TTC)(n) triplet expansion using magnetic DNA hybridization with reporter probes containing guanine units ( the TTC trinucleotide repeat expansion is associated with serious hereditary diseases, including Friedreich ataxia).