The Biomedical Application of Conducting Polymers for the Electrochemical Detection of Diseases
Date
2021-08
Authors
Runsewe, Damilola
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Abstract
Conducting polymers possess electroactive properties in the presence of an electric field. They have potential applications in alternative energy, sensors, display technologies, and biomedicine. In combination with biorecognition molecules like DNA aptamers or antibodies, conducting polymers can be used as biosensing devices for the detection and monitoring of illnesses. The major advantage they provide is in the potential to function as portable, rapid, inexpensive biosensors when compared to what is currently available. In this work, an electrochemical biosensor for the detection of the small molecule adenosine and two cancer-associated mucin 1 polypeptides was developed utilizing a conductive copolymer a transducing agent. First, a method was developed to modify the surface of indium tin oxide slides to enable robust copolymer deposition. The poly(3,4-ethylene dioxythiophene) (PEDOT) and poly(2,2'-(3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine-3,3-diyl)diacetic acid (PProDOT-(COOH)2) copolymer was electrochemically grown on the surface of the modified slides. This copolymer was used to covalently attach target-specific aptamers to the biosensing platform to provide the system with target selectivity. The electroactivity of the conducting polymer before and after aptamer attachment, in polar and aqueous electrolyte solutions, was studied. The attachment of the aptamers to the conducting polymer was confirmed with fluorescence microscopy and cyclic voltammetry. The fabricated aptamer-based sensors were then used for the electrochemical detection of adenosine and two mucin 1 polypeptides (short peptide: (APDTRPAPG, long peptide: PDTRPAPGSTAPPAHGVTSA), respectively, and the performance of each sensor was characterized The adenosine aptasensor had a limit of detection of 2.33 nM and a linear range of 9.6 nM to 600 μM, while the mucin 1 aptasensor had a limit of detection of 5.92 fg/mL for the short mucin 1 peptide and 92.14 pg/mL for the long mucin 1 peptide. The mucin 1 aptasensor had a linear range of 62.5 pg/mL to 6.25 μg/mL for the short mucin 1 peptide and 625 pg/mL to 12.5 μg/mL for the long mucin 1 peptide. Both adenosine and mucin aptasensors showed good selectivity against competing interfering agents and specificity relative to scrambled oligonucleotide stands. In addition, both sensors showed stability for 0 to 6 days when stored in 0.1 M phosphate buffered saline.
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Keywords
conducting polymers, aptamers
Citation
Runsewe, D. (2021). The biomedical application of conducting polymers for the electrochemical detection of diseases (Unpublished dissertation). Texas State University, San Marcos, Texas.