title: An RNA aptamer-based electrochemical biosensor for detection of theophylline in serum.
abstract: An electrochemical RNA aptamer-based biosensor for rapid and label-free detection of the bronchodilator theophylline was developed. The 5'-disulfide-functionalized end of the RNA aptamer sequence was immobilized on a gold electrode, and the 3'-amino-functionalized end was conjugated with a ferrocene (Fc) redox probe. Upon binding of theophylline the aptamer switches conformation from an open unfolded state to a closed hairpin-type conformation, resulting in the increased electron-transfer efficiency between Fc and the electrode. The electrochemical response, which was measured by differential pulse voltammetry, reaches saturation within a few minutes after addition of theophylline, and the dynamic range for detecting theophylline is 0.2-10 muM. The electrode displays an inhibited response when applied directly in serum samples treated with RNase inhibitors; however a full response to the theophylline serum concentration was obtained by transferring the electrode to blank serum-free buffer solutions. It was demonstrated that theophylline is detected with high selectivity in the presence of caffeine and theobromine.
authors.affiliation: Danish National Research Foundation: Centre for DNA Nanotechnology (CDNA), Department of Chemistry and iNANO, The Faculty of Science, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark. e_ferapontova@chem.au.dk
authors.forename: Elena E
authors.initials: EE
authors.lastname: Ferapontova
authors.forename: Eva M
authors.initials: EM
authors.lastname: Olsen
authors.forename: Kurt V
authors.initials: KV
authors.lastname: Gothelf
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D001483:Base Sequence; D015374:Biosensing Techniques / Q000379:methods*; D004563:Electrochemistry; D004566:Electrodes; D006046:Gold / Q000737:chemistry; D006801:Humans; D012680:Sensitivity and Specificity; D013499:Surface Properties; D013806:Theophylline / Q000097:blood*
chemical_list: D052157:Aptamers, Nucleotide; D006046:Gold; D013806:Theophylline