Innovative polymer engineering for the investigation of electrochemical properties and biosensing ability.

Subtle engineering for the generation of a biosensor from a conjugated polymer with the inclusion of fluorine-substituted benzothiadiazole and indole moieties is reported. The engineering includes the electrochemical copolymerization of the indole-6-carboxylic acid ( M1 ) and 5-fluoro-4,7-bis(4-hexylthiophen-2-yl)benzo[ c ][1,2,5]thiadiazole ( M2 ) on the indium tin oxide and graphite electrode surfaces for the investigation of both their electrochemical properties and biosensing abilities with their copolymer counterparts. The intermediates and final conjugated polymers, Poly(M1) [P-In6C] , Poly(M2) [P-FBTz] , and copoly(M1 and M2) [P-In6CFBTz] , were entirely characterized by 1 H NMR, 13 C NMR, CV, UV-Vis-NIR spectrophotometry, and SEM techniques. HOMO energy levels of electrochemically obtained polymers were calculated from the oxidation onsets in anodic scans as -4.78 eV, -5.23 eV, and -4.89 eV, and optical bandgap (Eg op ) values were calculated from the onset of the lowest-energy π-π* transitions as 2.26 eV, 1.43 eV, and 1.59 eV for P-In6C , P-FBTz , and P-In6CFBTz , respectively. By incorporation of fluorine-substituted benzothiadiazole ( M2 ) into the polymer backbone by electrochemical copolymerization, the poor electrochemical properties of P-In6C were remarkably improved. The polymer P-In6CFBTz demonstrated striking electrochemical properties such as a lower optical band gap, red-shifted absorption, multielectrochromic behavior, a lower switching time, and higher optical contrast. Overall, the newly developed copolymer, which combined the features of each monomer, showed superior electrochemical properties and was tested as a glucose-sensing framework, offering a low detection limit (0.011 mM) and a wide linear range (0.05-0.75 mM) with high sensitivity (44.056 μA mM - 1 cm - 2 ).