Nanocomposite based on Poly (para-phenylene)/Chemical Reduced Graphene Oxide as a Platform for Simultaneous Detection of Ascorbic Acid, Dopamine and Uric Acid.

In this study, an efficient and simple designed nanohybrid created for individual and simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). This nanohybrid is a combination of reduced graphene oxide (CRGO) and redox poly(para-phenylene) (Fc-ac-PP) modified in a lateral position with ferrrocenyl group CRGO/Fc-ac-PPP. The CRGO/Fc-ac-PPP nanohybrid demonstrated a synergistic effect resulting in a large conductivity, surface area and catalytic properties provided by the redox attached ferrocene. Moreover, this nanocomposite is able to detect individually as well as simultaneously AA, DA and UA in a co-existence system with defined and separated redox peaks oxidation. The linear response ranges for AA, DA and UA, when detected simultaneously, are 0.1-10000 µM, 0.0001-1000 µM and 0.1-10000 µM, respectively, and the detection limits (S/N = 3) are 0.046 µM, 0.2 nM and 0.013 µM, respectively. The proposed sensor shown satisfactory results when applied to real spiked urine samples for measuring the abnormal high or lowconcentration of AA, DA and UA in vivo.

Direct E-DNA sensor of Mycobacterium tuberculosis mutant strain based on new nanocomposite transducer (Fc-ac-OMPA/MWCNTs).

Direct DNA sensor based on new nanocomposite materials (Fc-ac-OMPA/MWCNTs) has been investigated. This nanocomposite was formed by combining the redox oligomer "oligo-methoxy-phenyl-acetonitrile" (Fc-ac-OMPA) and the MWCNTs via a simple π-π stacking interaction in the aim to ameliorate the biosensor performance. The redox indicator and the functional groups of the redox oligomer have been used for monitoring the electrochemical behavior and the flexibility for direct covalent attachment of Hepatitis C DNA probe. This nanocomposite shows high performance of DNA hybridization with a detection limit of 0.08 fmol L-1. Moreover, the biosensor was applied for the detection of pathogenic bacterium such as DNA from Mycobacterium tuberculosis strand. Developed biosensor has been able to detect a single nucleotide polymorphism (SNP)T (TCG/ TTG) which confers resistance of M. tuberculosis to rifampicin drug.

Direct Electrochemical DNA Sensor based on a new redox oligomer modified with ferrocene and carboxylic acid: Application to the detection of Mycobacterium tuberculosis mutant strain.

A new redox oligomer "oligo-methoxy-phenyl-acetonitrile" (Fc-acid-OMPA) modified with ferrocene groups and carboxylic acids as functional groups in side chains, has been synthesized. The redox indicator has been used for monitoring the electrochemical behavior. The functional groups give the flexibility for direct covalent attachment of biomolecules. The electrochemical properties of the redox oligomer film deposited on gold electrodes have been studied by cyclic voltammetry (CV), which showed a rate of electron transfer of 6.43 s-1. The oligomer has been studied as a transducer for electrochemical DNA sensing and for this purpose the acid functional group of Fc-acid-OMPA was attached with the DNA probe of hepatitis C bearing amino group in 5' position through amid link. The efficiency of DNA attachment on the oligomer film has been analyzed by X-Ray Photoelectron Spectrometry (XPS) and FT-IR spectroscopy. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) have been used to analyze the biosensor construction and DNA detection. A wide linear range of detection from 1 fM to 100 pM have been demonstrated with a limit of detection (LOD) of 0.2 fM. The biosensor has showed an appreciated sensitivity to PCR samples of genomic DNA from Mycobacterium tuberculosis, and has been able to detect a single mutation which confers resistance of M. tuberculosis to rifampicin drug.