Merve Sendur

A novel promising biomolecule immobilization matrix: Synthesis of functional benzimidazole containing conducting polymer and its biosensor applications

In order to construct a robust covalent binding between biomolecule and immobilization platform in biosensor preparation, a novel functional monomer 4-(4,7-di(thiophen-2-yl)-1H-benzo[d]imidazol-2-yl)benzaldehyde (BIBA) was designed and successfully synthesized. After electropolymerization of this monomer, electrochemical and spectroelectrochemical properties were investigated in detail. To fabricate the desired biosensor, glucose oxidase (GOx) was immobilized as a model enzyme on the polymer coated graphite electrode with the help of glutaraldehyde (GA). During the immobilization step, an imine bond was formed between the free amino groups of enzyme and aldehyde group of polymer. The surface characterization and morphology were investigated to confirm bioconjugation by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) at each step of biosensor fabrication. The optimized biosensor shows good linearity between 0.02mM and 1.20mM and a low limit of detection (LOD) of 2.29μM. Kinetic parameters Km(app) and Imax were determined as 0.94mM and 10.91μA, respectively. The biosensor was tested for human blood serum samples.

A promising combination of benzotriazole and quinoxaline units: A new acceptor moiety toward synthesis of multipurpose donor–acceptor type polymers

By combining benzotriazole and quinoxaline units in an acceptor unit, three novel monomers, 2-dodecyl-6,7-diphenyl-4,9-di(thiophen-2-yl)-2H-[1,2,3]triazolo[4,5-g]quinoxaline (M1), 2-dodecyl-4,6,7,9-tetra(thiophen-2-yl)-2H-[1,2,3]triazolo[4,5-g]quinoxaline (M2) and 6,7-bis(4-tert-butylphenyl)-2-dodecyl-4,9-di(thiophen-2-yl)-2H-[1,2,3]triazolo[4,5-g]quinoxaline (M3), were synthesized and polymerized electrochemically. All polymers revealed both p- and n-type doping properties under ambient conditions. As found by spectroelectrochemical studies they have small band gaps, ca. 1.00 eV. The polymers revealed two distinct absorption bands as all green coloured neutral state donor–acceptor–donor type polymers should have. Besides this, all have broad absorptions covering the region between 700 nm and 1000 nm which is rarely seen in electrochromic polymers. Due to these promising features, they are considered to be potential materials for optoelectronics.