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Electrochemical DNA sensor for anthrax toxin activator gene atxA-detection of PCR amplicons

Das, Ritu, Goel, Ajay K., Sharma, Mukesh K., Upadhyay, Sanjay
Biosensors & bioelectronics 2015 v.74 pp. 939-946
Bacillus anthracis, DNA, anthrax toxin, atomic force microscopy, biosensors, detection limit, dielectric spectroscopy, electrochemistry, electrodes, nanogold, nucleic acid hybridization, polymerase chain reaction, regulator genes
We report the DNA probe functionalized electrochemical genosensor for the detection of Bacillus anthracis, specific towards the regulatory gene atxA. The DNA sensor is fabricated on electrochemically deposited gold nanoparticle on self assembled layer of (3-Mercaptopropyl) trimethoxysilane (MPTS) on GC electrode. DNA hybridization is monitored by differential pulse voltammogram (DPV). The modified GC electrode is characterized by atomic force microscopy (AFM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) method. We also quantified the DNA probe density on electrode surface by the chronocoulometric method. The detection is specific and selective for atxA gene by DNA probe on the electrode surface. No report is available for the detection of B. anthracis by using atxA an anthrax toxin activator gene. In the light of real and complex sample, we have studied the PCR amplicons of 303, 361 and 568 base pairs by using symmetric and asymmetric PCR approaches. The DNA probe of atxA gene efficiently hybridizes with different base pairs of PCR amplicons. The detection limit is found to be 1.0pM (S/N ratio=3). The results indicate that the DNA sensor is able to detect synthetic target as well as PCR amplicons of different base pairs.