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Functionalized micro/nanomotors having immobilized biological molecules provide excellent and powerful tools for the detection of target molecules. Based on surface modifications and mobilities of micromotors, we report herein a new experimental design of high-speed, self-propelled and plasma modified micromotors for biomedical applications. Within this scope, in the first step, poly (3,4-ethylenedioxythiophene) (PEDOT) was in-situ synthesized onto W 5 O 14 (tungsten trioxide) wires by using radio frequency (RF) rotating plasma reactor. Then, W 5 O 14 /PEDOT-Platinum (Pt) hybrid micromotors were fabricated by using magnetron sputtering technique. The detection of miRNA-21 was performed using both single-stranded DNA (ssDNA) (probe DNA) immobilized W 5 O 14 -Pt and W 5 O 14 /PEDOT-Pt micromotors. The fluorescence signals were determined after hybridization of probe DNA immobilized these novel W 5 O 14 -Pt and W 5 O 14 /PEDOT-Pt micromotors with different molar concentrations of the synthetic target (6-carboxyfluorescein dye (FAM)-labeled miRNA-21). The changes in the micromotor speeds after the hybridization process were also evaluated. W 5 O 14 /PEDOT-Pt micromotors presented better sensor properties compared to the W 5 O 14 -Pt micromotors. A good linearity for miRNA-21 concentration between 0.1 nM and 100 nM was obtained for these micromotors based on their fluorescence intensities. The detection limit was found as 0.028 nM for W 5 O 14 /PEDOT-Pt micromotors (n = 3). Thus, sensor and motor characteristics of the W 5 O 14 -Pt micromotors were improved by RF plasma enhanced PEDOT coatings. The new catalytic W 5 O 14 based micromotors demonstrated here had great potential for the development of sensitive and simple sensing platforms for detection of miRNA-21., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Biosensors can deliver the rapid bacterial detection that is needed in many fields including food safety, clinical diagnostics, biosafety and biosecurity. Whole-cell imprinted polymers have the potential to be applied as recognition elements in biosensors for selective bacterial detection. In this paper, we report on the use of 3-aminophenylboronic acid (3-APBA) for the electrochemical fabrication of a cell-imprinted polymer (CIP). The use of a monomer bearing a boronic acid group, with its ability to specifically interact with cis-diol, allowed the formation of a polymeric network presenting both morphological and chemical recognition abilities. A particularly beneficial feature of the proposed approach is the reversibility of the cis-diol-boronic group complex, which facilitates easy release of the captured bacterial cells and subsequent regeneration of the CIP. Staphylococcus epidermidis was used as the model target bacteria for the CIP and electrochemical impedance spectroscopy (EIS) was explored for the label-free detection of the target bacteria. The modified electrodes showed a linear response over the range of 10 3 -10 7 cfu/mL. A selectivity study also showed that the CIP could discriminate its target from non-target bacteria having similar shape. The CIPs had high affinity and specificity for bacterial detection and provided a switchable interface for easy removal of bacterial cell., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The need for sensitive, selective, rapid and low-cost detection systems for DNA and DNA-drug interactions are in crucial demand for diagnostics and real-world applications. This work details the preparation of poly(3,4-ethylenedioxythiophene) (PEDOT) coated chitosan (CHIT) and the use of PEDOT coated CHIT modified disposable pencil graphite electrodes (PGEs) for DNA and DNA-anticancer drug interaction sensing. PEDOT coated CHIT (PEDOT/CHIT) was prepared with rotating plasma polymerization using radio frequency (RF: 13.56 MHz) power generator. Then, modification of PEDOT/CHIT onto PGE was performed. The use of the prepared electrode was carried out using differential pulse voltammetry (DPV). Cyclic voltammetry (CV) and scanning electron microscopy (SEM) were used to characterize the PEDOT/CHIT/PGE. The performance of the electrode was compared with CHIT/PGE and unmodified PGE. The electrode exhibited high sensitivity for the investigation of DNA sensing and DNA-anticancer drug interaction. Such disposable sensing platform hold considerable promise for diverse bioapplications., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Electrochemical characterization of redox polymer for monitoring of adenine was described in this study using poly(vinylferrocenium) (PVF(+)) modified platinum (Pt) electrode. Scanning electron microscope (SEM) was used for the surface characterization. The electrochemical behaviors of polymer modified and adenine immobilized polymer modified electrodes were investigated by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In order to obtain more sensitive and improved electrochemical signals, analytical parameters such as the effects of polymeric film thickness, immobilization time of adenine, pH and adenine concentration were examined on the response of the polymer modified electrode. Alternating current (AC) impedance spectroscopy was used for the characterization of polymer modified and adenine immobilized polymer modified electrodes. The effect of possible interferents on the response of the electrode was examined., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Single-walled carbon nanotubes (SWCNT)-poly(vinylferrocenium) (PVF(+)) modified pencil graphite electrodes (PGEs) were developed in our study for the electrochemical monitoring of a sequence-selective DNA hybridization event. Firstly, SWCNT-PVF(+) modified PGE, PVF(+) modified PGE and unmodified PGE were characterized using scanning electron microscopy (SEM). The electrochemical behavior of these electrodes was then investigated using electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The SWCNT-PVF(+) modified PGEs were optimized for improved DNA sensing ability by measuring the guanine oxidation signal. In order to obtain the full coverage immobilization of the DNA probe following the optimum working conditions, the effect of amino-linked, thiol-linked and, bare oligonucleotides (ODNs), and the concentration of the DNA probe on the response of the modified electrode were examined. After optimization studies, the sequence-selective DNA hybridization was evaluated in the case of hybridization between an amino-linked probe and its complementary (target), a noncomplementary (NC) sequence, calf thymus double stranded DNA (dsDNA), and target/mismatch (MM) mixtures in the ratio of 1:1. SWCNT-PVF(+) modified PGEs presented very effective discrimination of DNA hybridization owing to their superior selectivity and sensitivity., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Abstract: In this study, ZnO nanoparticles (ZNP) of approximately 30nm in size were synthesized by the hydrothermal method and characterized by X-ray diffraction (XRD), Braun–Emmet–Teller (BET) N2 adsorption analysis and transmission electron microscopy (TEM). ZnO nanoparticles enriched with poly(vinylferrocenium) (PVF+) modified single-use graphite electrodes were then developed for the electrochemical monitoring of nucleic acid hybridization related to the Hepatitis B Virus (HBV). Firstly, the surfaces of polymer modified and polymer–ZnO nanoparticle modified single-use pencil graphite electrodes (PGEs) were characterized using scanning electron microscopy (SEM). The electrochemical behavior of these electrodes was also investigated using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Subsequently, the polymer–ZnO nanoparticle modified PGEs were evaluated for the electrochemical detection of DNA based on the changes at the guanine oxidation signals. Various modifications in DNA oligonucleotides and probe concentrations were examined in order to optimize the electrochemical signals that were generated by means of nucleic acid hybridization. After the optimization studies, the sequence-selective DNA hybridization was investigated in the case of a complementary amino linked probe (target), or noncomplementary (NC) sequences, or target and mismatch (MM) mixture in the ratio of (1:1). [Copyright &y& Elsevier]

Poly(vinylferrocenium) (PVF) modified gold (Au) electrode was developed in this study for the electrochemical sensing of deoxyribonucleic acid (DNA) hybridization based on the oxidation signals of polymer and guanine, and also for the electrochemical investigation of interaction of anticancer drug, mitomycin C (MC) and DNA immobilized onto PVF modified Au electrode. PVF modified Au electrode was prepared by electrooxidation of poly(vinylferrocene) PVF at +0.7 V versus Ag/AgCl reference electrode. The polymer modified electrode and DNA immobilized polymer modified electrode were characterized by X-ray photoelectron (XPS), Fourier transform infrared-attenuated total reflentance (FTIR-ATR) and alternating current (AC) impedance spectroscopy. For application studies, differential pulse voltammetry (DPV) technique was used. [ABSTRACT FROM AUTHOR]

Abstract: In this study, SnO2 nanoparticles (SNPs)-poly(vinylferrocenium) (PVF+) modified single-use graphite electrodes were developed for electrochemical monitoring of DNA hybridization. The surfaces of polymer modified and polymer–SNP modified pencil graphite electrodes (PGEs) were firstly characterized by using SEM analysis. The electrochemical behaviours of these electrodes were also investigated using the differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. The polymer–SNP modified PGEs were then tested for the electrochemical sensing of DNA based on the changes at the guanine oxidation signals. Experimental parameters, such as; different modifications in DNA oligonucleotides, DNA probe concentrations were examined to obtain more sensitive and selective electrochemical signals for nucleic acid hybridization. After optimization studies, DNA hybridization was investigated in the case of complementary of hepatitis B virus (HBV) probe, mismatch (MM), and noncomplementary (NC) sequences. [ABSTRACT FROM AUTHOR]

Abstract: Poly(vinylferrocenium) (PVF+) modified electrode was developed in this study for the electrochemical sensing of DNA based on the oxidation signals of polymer, adenine and guanine. Experimental parameters, such as; polymeric film thickness, DNA immobilization time and DNA concentration were examined in order to obtain more sensitive and selective electrochemical signals. After optimization studies, DNA hybridization was investigated. [Copyright &y& Elsevier]