Pure polyacrylonitrile (PAN) and polyacrylonitrile/polyaniline (PAN/PAni) hybrid nanofibers (NFs) were produced via electrospinning and used to monitor guanine oxidation in single strand DNA (ssDNA) by electrochemical methods. Two different methodologies were conducted. First, pre‐synthesized PAni was added into electrospinning PAN solution and electrospun into composite PAN/PAni nanofibrous structure on cylindrical pencil graphite (PGE) surface. In the second route, PAN NFs were electrospun on a PGE surfaces and polymerization of PAni was conducted on the surfaces of the as‐spun PAN NFs. NFs were kept at −18 °C in a refrigerator for several days. ssDNA was immobilized on the prepared NFs and guanine oxidation signals were observed for each system. The results revealed that use of PAN NFs enhanced signal intensity from 0.92 µA (PGE) to 1.04 µA (PAN NFs). Addition of PAni to PAN increased signal intensity to 1.23 µA. When the PAN NF surfaces were coated with PAni, signal enhancement continued to increase up to 4.19 µA for fourth day and decreased again when PAni‐coated NFs were kept at −18 °C in the refrigerator. Since the prepared system is fast and cheap, it is promising for application in DNA biosensor devices. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45567.

Cellulose monoacetate/Nafion (CMA/N) hybrid nanofibers were produced via a one-step electrospinning method. Nanofibers morphologies transformed from uniform to bead on a string defect morphology with increasing Nafion ratio in CMA/N hybrid nanofibers. The melting point of CMA was detectable at DSC measurement, but since the addition of Nafion did not allow a proper crystallization of CMA, melting peak disappeared after the Nafion addition. Decomposition temperature decreased dramatically with the addition of Nafion into CMA/N nanofibers and decomposition took place at a broad temperature range. Nanofibers were also electrospun on the cylindrical graphite electrode for DNA electrochemical sensor analysis. Unmodified and NHmodified single strand DNA molecules were immobilized via physical adsorption method on the asprepared nanofiber sensory system. Electrochemical analysis were performed via differential pulse voltammetry (DPV) to observe the guanine oxidation signal at unmodified and NH-modified DNA. Maximum oxidation signals were detected from pure CMA nanofibers at unmodified DNA. Signal intensity increased with the addition of Nafion into CMA/N nanofibers at NH-modified DNA sample comparing to unmodified DNA. It was concluded that DNA molecules could be properly immobilized on the produced CMA/N hybrid nanofibers via physical adsorption method and used as electrochemical DNA biosensor.

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Effect of sulfuric acid (SA) on the heat treatment of electrospun polyacrylonitrile (PAN) fibers and their application on guanine oxidation detection in single‐strand DNA molecules (ssDNA) were studied. In this regard, two different approaches were performed. Aqueous sulfuric acid solutions were poured on the pure PAN nanofibers and heat treatment process was performed to determine the maximum temperature at which fiber structures does not deteriorate. Also, SA was directly added into electrospinning solutions with different ratios and heat treatment process was applied to the as‐spun PAN/SA fibers. The fibers were produced both directly on a grounded plate and cylindrical pencil graphite surfaces (PGE) for the fiber characterizations and biosensor measurements. Single strand DNA (ssDNA) molecules were immobilized on the samples for the electrochemical investigation of guanine oxidation signal. 0.971 and 3.69 μA guanine oxidation signal intensities were detected for neat PGE and heat‐treated PAN/SA fiber coated PGE. The formation of sulfonic groups on the fibers has driven more ssDNA attachment on the surface, and hence increased the guanine oxidation signal intensity dramatically (about 261.4% increment). The results have shown promising future of heat‐treated PAN/SA micro/nanofibers for sensitive detection of guanine oxidation signal from genetic molecules.