Towards the Development of a Direct Electrochemical Biodetector of Avidin Based on the Poly(chloro amino-β-styryl terthiophene)-Coated Glassy Carbon Electrode

Abstract

In this study, a simple and direct biodetector was proposed, which was based on biotin immobilized onto a conducting polymer-coated electrode, for the detection of avidin, a highly stable glycoprotein found in egg-whites. Biotin was immobilized onto the electrode by covalent coupling to the primary amine group on the poly 3′-(3-chloro-4-amino-β-styryl)-(2,2′ : 5′,2″-terthiophene) (PCAST), and the biotin–avidin interaction was monitored by cyclic voltammetry. Incubation of the PCAST/biotin-modified-coated electrode with avidin in a phosphate buffered saline solution caused a significant change to its cyclic voltammogram, which was explained by the binding of avidin by biotin, and resulted in restricted ion transfer to and from the conducting polymer. This change was then utilized to detect avidin at 4 × 10–6 mol L–1.

Thiophene-Based Trimers and Their Bioapplications: An Overview

“…Trimers carrying aliphatic and aromatic amines not directly linked to the thiophene ring are also well-documented in literature. For example, amino-styril [ 210 , 211 , 212 ] and aminopyrimidyl [ 212 , 213 , 214 , 215 , 216 , 217 , 218 ] trimers were abundantly employed for sensing and biological applications, as well as aminoacid-linked trimers [ 200 , 219 ]. Some examples are shown in Scheme 11 .…”

“…In this way, electron delocalization between the two aromatic systems is preserved. By alkene group formation, benzene [ 338 ], naphthalene [ 448 ], anthracene [ 448 ] and pyrene [ 449 ] where connected to the trimer, as well as substituted phenyl groups [ 195 , 210 , 310 , 338 , 450 , 451 , 452 , 453 ], pyridines [ 148 , 339 , 454 ], thiophenes [ 454 , 455 , 456 ], and ferrocene [ 457 ]. Through alkyne bridge, mono-, bis- and ter-pyridines were attached [ 162 , 236 , 458 , 459 ], as well as fullerenes [ 460 , 461 ].…”

“…The as-prepared sensor was succesfully employed for the detection of avidin, a highly stable glycoprotein found in egg-whites, showing a linear response between 4 × 10 −14 and 3 × 10 −4 mol/L and a detection limit of ca. 10 −14 mol/L [ 210 , 211 ]. Due to its large-scale usage as antioxidant, ascorbic acid is another highly interesting target molecule.…”