Functionalized Thiophene-Based Aptasensors for the Electrochemical Detection of Mucin-1

Abstract

Mucin-1 (MUC1) is a glycoprotein found in epithelial tissues; its function is to protect the body by blocking pathogens from reaching the cells. Overexpression and elevated serum levels of this protein are observed in breast cancer, lung cancer, stomach cancer, ovarian cancer, and many other types of malignancies. Current methods used to detect cancer are expensive and therefore not readily accessible; some methods are also invasive. The ability to detect MUC1 could allow for early detection of cancer, leading to more successful outcomes. This research focuses on the development of a robust biosensor platform based on aptamer-functionalized electroactive polymers (EAPs) that can be used for the detection of cancer. To achieve this, indium tin oxide slide surfaces were modified to enable the electrochemical growth of an electroactive copolymer of 3,4-ethylenedioxythiophene (EDOT) and 2,2-(3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine-3,3-diyl)diacetic acid (ProDOT(COOH)2), with the carboxylic acid functionalities added to introduce bonding sites for a MUC1-specific aptamer. Three copolymer ratios were investigated to maximize the performance. The aptamer was then attached to the EAPs to create aptasensors that could be used for the electrochemical detection of a MUC1 polypeptide. The limits of detection of the biosensors and their stabilities were evaluated. The MUC1 aptasensor showed stability for at least 6 days, depending on the ratio of the copolymer, when stored in 0.1 M phosphate-buffered saline. The 1:2 EDOT/ProDOT(COOH)2 copolymer was found to be the most stable over time and to offer one of the smallest limits of detection, making it the most favorable ratio for aptasensor optimization. Specifically, the 1:2 EDOT/ProDOT(COOH)2 biosensor provided a limit of detection of 369 fg/mL (418 fM) and a linear range of 625 fg/mL to 6.25 ng/mL (709 fM to 7.09 nM) with the MUC1 peptide APDTRPAPG. The sensor also showed selectivity when tested with competing agents including IgG and cell media. The performance of the aptasensor demonstrated its potential as a highly sensitive and selective biosensor for MUC1 detection.

4,4’-(Thiophene-2,5-diylbis(ethyne-2,1-diyl))bis(1-methyl-1-pyridinium) Iodide

“…The synthetic route followed for the target compound is shown in Scheme 1 and includes four straightforward and high-yielding steps, starting from readily affordable 2,5-diiodothiophene. The choice of this compound as a starting material for the construction of an extended, conjugated viologen-type salt, with effective light interaction, was motivated by the widely recognized optoelectronic properties of thiophene derivatives [19], which are particularly exploited as oligomers and polymers for molecular electronics [20], OLEDs [21], emerging photovoltaics [22] and chemo-and biosensors [23]. The heteroaromatic core was linked to the pyridinium rings by palladiumcopper-catalyzed Sonogashira cross-coupling [24], thus profiting from both the effectiveness of this reaction and the ability of triple bonds to enable conjugation.…”

Current Trends in the Use of Semiconducting Materials for Electrochemical Aptasensing

“…Other electroactive copolymers such as 3,4-ethylenedioxythiophene (EDOT) and 2,2-(3,4-dihydro-2H-thieno [3,4-b][1,4]dioxepine-3,3-diyl)diacetic acid (ProDOT(COOH) 2 ) can be used for the immobilization of the amino-modified aptamers to their carboxylic groups. This approach has been reported by Haya et al [77] for the development of an electrochemical aptasensor for the detection of the MUC1 cancer marker. The aptasensor allowed for the electrochemical detection of MUC1 with an LOD of 418 fM and a linear range of 709 fM to 7.09 nM.…”

“…AFM1 induced a decrease in the cathodic peak related to the neutral red that served as a probe. This approach has been reported by Haya et al [77] for the development of an electrochemical aptasensor for the detection of the MUC1 cancer marker. The aptasensor allowed for the electrochemical detection of MUC1 with an LOD of 418 fM and a linear range of 709 fM to 7.09 nM.…”