Synthesis, characterization and electrochromic properties of copolymer of terephthalic acid bis-(thiophen-3-yl-methyl) thioester with thiophene

Terephthalic acid bis-(thiophen-3-yl-methyl thioester) (TTMT) was synthesized via the reaction of thiophen-3-yl methanethiol with terephthaloyl dichloride. Nuclear magnetic resonance ( H-1-NMR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy were utilized for the characterization of the monomer. Electrochemical copolymerization of TTMT with thiophene in acetonitrile/boron trifluoride diethyl etherate (AN/BFEE) (8:2, v/v) solvent mixture was realized by using tetrabutylammonium tetrafluoroborate (TBAFB) as the supporting electrolyte. The resulting copolymer was characterized via cyclic voltammetry (CV), FTIR, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), four-probe technique conductivity measurement and UV-Vis spectroscopy. Spectroelectrochemical analysis of the copolymer, P(TTMT-co-Th), reflected pi to pi* transition at 476 nm and band gap was calculated as 2.03 eV. Kinetic studies were carried out upon measuring the percent transmittance (%T=16%) at the maximum contrast point and switching time (1.25 s). A dual type electrochromic device (ECD) of P(TTMT-co-Th) and poly(3,4-ethylenedioxythiophene) (PEDOT) was constructed. Spectroelectrochemistry, switching ability, open circuit memory and stability of the device were examined by UV-Vis spectroscopy and cyclic voltammetry. The device switches between brown and blue, exhibits 0.0 V and 2.6 V as the switching voltages and short switching time (1.03 s)

A Novel and Effective Surface Design: Conducting Polymer/β-Cyclodextrin Host–Guest System for Cholesterol Biosensor

The combination of supramolecules and conducting polymers (CPs) has gained much attention for the development of new immobilization matrices for biomolecules. Herein, an amperometric biosensor based on a novel conducting polymer, poly(2-(2-octyldodecyl)-4,7-di(selenoph-2-yl)-2H-benzo[d][1,2,3]triazole)) (PSBTz) and beta-cyclodextrin (beta-CD) for the detection of cholesterol, was constructed. The PSBTz film with beta-CD was deposited on a graphite electrode by electropolymerization technique to achieve a suitable matrix for enzyme immobilization. Moreover, to justify the immobilization, alkyl chain containing conducting polymer (PSBTz) was designed, synthesized and electrochemically polymerized on the transducer surface. Alkyl chains in the structure of SBTz and hydroxyl groups of beta-CD contributed to effective immobilization while protecting the suitable orientation of the biomolecule. Cholesterol oxidase (ChOx) was covalently immobilized onto the modified surface using N,N'-carbonyldiimidazole (CDI) as the cross-linking agent. After successful immobilization, amperometric biosensor responses were recorded at -0.7 V vs Ag/AgCl in phosphate buffer (pH 7.0). The apparent Michaelis-Menten constant (KMapp), maximum current (I-max), limit of detection (LOD), and sensitivity values were determined: 28.9 mu M, 12.1 mu A, 0.005 mu M, and 5.77 mu A/mu M cm(2), respectively. The fabricated biosensor was characterized using scanning electron microscopy (SEM) and cyclic voltammetry (CV) techniques. Finally, the prepared biosensor was successfully applied for the determination of cholesterol in blood samples