Amplified Electrochemical DNA Sensor Based on Polyaniline Film and Gold Nanoparticles (original) (raw)
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Sensors and Actuators B: Chemical, 2014
In this paper, fabrication of a biosensing platform by covalent attachment of biomolecules on PAni nanowire (NW) decorated with gold nanoparticles (AuNP) has been reported. Efficiency of the platform has been evaluated after attachment of three different biomolecules viz. glucose oxidase (GOx), a single stranded DNA (ssDNA) and Lamin A antibody (LAA) for sensing of glucose, complementary DNA strand and Lamin A protein, respectively. Method of immobilization as well as method of detection was somewhat different for different systems. GOx and LAA were attached via NH 2 functionalizations on AuNP while thiol-ended ssDNA was directly attached to AuNP surface. Sensing of glucose was monitored via chronoamperometry and the flow cell techniques while DNA detection was carried out via Differential Pulse Voltametry (DPV) and protein detection employing Electrochemical Impedance Spectroscopic (EIS) technique. Fabrication of the electrode was easy, enzymatic activity was well and reproducibility of the sensing process was good enough for sensing of glucose. The lower detection limit (1 M), higher sensitivity (14.63 A mM −1 cm −2), greater stability and the excellent specificity indicated excellence of glucose sensor. For DNA sensor, detection of non complementary and complementary strands, even single base mismatch could be well discriminated up to the analyte concentration as low as 1 M. The similar detection limit was also obtained for detection of protein all which proves the suitability of the Au-PAni nanocomposites as a general sensor platform.
Electrochimica Acta, 2006
A novel and sensitive electrochemical DNA biosensor based on electrochemically fabricated polyaniline nanowire and methylene blue for DNA hybridization detection is presented. Nanowires of conducting polymers were directly synthesized through a three-step electrochemical deposition procedure in an aniline-containing electrolyte solution, by using the glassy carbon electrode (GCE) as the working electrode. The morphology of the polyaniline films was examined using a field emission scanning electron microscope (SEM). The diameters of the nanowires range from 80 to 100 nm. The polyaniline nanowires-coated electrode exhibited very good electrochemical conductivity. Oligonucleotides with phosphate groups at the 5 end were covalently linked onto the amino groups of polyaniline nanowires on the electrode. The hybridization events were monitored with differential pulse voltammetry (DPV) measurement using methylene blue (MB) as an indicator. The approach described here can effectively discriminate complementary from non-complementary DNA sequence, with a detection limit of 1.0 × 10 −12 mol l −1 of complementary target, suggesting that the polyaniline nanowires hold great promises for sensitive electrochemical biosensor applications.
An amperometric enzyme biosensor fabricated from polyaniline nanoparticles
…, 2005
The biosensor described here uses a novel aqueous-based nanoparticulate polyaniline (PANI), doped with dodecylbenzenesulfonic acid (DBSA). The nanoparticles were applied to a glassy carbon electrode surface by electrodeposition techniques, and horseradish peroxidase (HRP) was subsequently electrostatically adsorbed to the nanoparticle-modified surface. This biosensor format was demonstrated for H 2 O 2 sensing. Electrodeposited polymer nanoparticles resulted in highly ordered conductive nanostructured films, which were examined by scanning electron microscopy (SEM), atomic force microscopy (AFM), profilometry and spectroelectrochemistry. The surface of the films were characterized by a uniform array of nanoparticulate PANI (nanoPANI/DBSA) nodules and were shown to have a thickness of 350 nm. Physical techniques have shown that the nanofilms possess properties which allow for uniform electrostatic adsorption of protein to take place. This effective biosensor format, exhibits higher signal-tobackground ratios and shorter response times than previous PANI biosensor configurations.
Bioelectrochemistry, 2010
In this article, a simple strategy of electroless deposition for gold nanoparticle (Au NP) modification on the conductive substrate is developed. The morphology of Au NP modified electrode could be controlled to some extent by choosing different solution concentrations, deposition times, etc. The Au NP modification increased the electrode surface area largely, and the surface area after Au NP modification on the polyelectrolyte multilayer (PEM) assembled electrode was about 3.3 times that of the planar gold electrode. The enhancement of DNA immobilization and hybridization on the Au NP modified electrode were characterized by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) with the use of Ru(NH 3 ) 6 3+ as an electrochemical redox indicator. With this approach, the sensitivity of Au NP modified PEM electrode for target DNA could reach 1 × 10 − 11 M. Compared with that of planar gold electrode, the detection limit was increased to be about 3 orders of magnitude.
Sensors
A DNA sensor has been proposed on the platform of glassy carbon electrode modified with native DNA implemented between two electropolymerized layers of polyaniline. The surface layer was assembled by consecutive stages of potentiodynamic electrolysis, DNA drop casting, and second electrolysis, which was required for capsulation of the DNA molecules and prevented their leaching into the solution. Surface layer assembling was controlled by cyclic voltammetry, electrochemical impedance spectroscopy, atomic force, and scanning electron microscopy. For doxorubicin measurement, the DNA sensor was first incubated in the Methylene blue solution that amplified signal due to DNA intercalation and competition with the doxorubicin molecules for the DNA binding sites. The charge transfer resistance of the inner layer interface decreased with the doxorubicin concentration in the range from 1.0 pM to 0.1 μM (LOD 0.6 pM). The DNA sensor was tested for the analysis of spiked artificial urine samples...
High sensitivity DNA detection using gold nanoparticle functionalised polyaniline nanofibres
Biosensors & Bioelectronics, 2011
Polyaniline (PANI) nanofibres (PANI-NF) have been modified with chemically grown gold nanoparticles to give a nanocomposite material (PANI-NF–AuNP) and deposited on gold electrodes. Single stranded capture DNA was then bound to the gold nanoparticles and the underlying gold electrode and allowed to hybridise with a complementary target strand that is uniquely associated with the pathogen, Staphylococcus aureus (S. aureus), that causes mastitis. Significantly, cyclic voltammetry demonstrates that deposition of the gold nanoparticles increases the area available for DNA immobilisation by a factor of approximately 4. EPR reveals that the addition of the Au nanoparticles efficiently decreases the interactions between adjacent PANI chains and/or motional broadening. Finally, a second horseradish peroxidase (HRP) labelled DNA strand hybridises with the target allowing the concentration of the target DNA to be detected by monitoring the reduction of a hydroquinone mediator in solution. The sensors have a wide dynamic range, excellent ability to discriminate DNA mismatches and a high sensitivity. Semi-log plots of the pathogen DNA concentration vs. faradaic current were linear from 150 × 10−12 to 1 × 10−6 mol L−1 and pM concentrations could be detected without the need for molecular, e.g., PCR or NASBA, amplification.
Molecular Crystals and Liquid Crystals, 2010
Gold(111) electrodes modified with Self Assembled Monolayers (SAMs) of 4-Aminothiophenol (4-ATP) functionalized with Pd(II) colloid nanoparticles, have been constructed, characterized and used as template for the electropolymerization 15 of aniline (PANI) films. Cyclic voltammetry and UV-vis spectroscopy confirm the func-tionalization of the 4-ATP SAMs by Pd(II) complex nanoparticles. Atomic Force Microscopy (AFM) images and the cyclic voltammetry measurements reveal that polyaniline films grown on 4-ATP-Au(111) SAMs functionalized with Pd(II) complex nanoparticles, posses a nanostructured morphology constituted by globular 20 structures of nanometric size. The electropolymerization of PANI driven by repeated potentiodynamic cycles produces structures with average diameters in a range of 20 to 60 nm.
Fabrication of Biosensor Based on Polyaniline/Gold Nanorod Composite
International Journal of Electrochemistry, 2011
This present paper describes a new approach to fabricate a new amperometric sensor for the determination of glucose. Polyaniline (PANI) film doped with colloidal gold nanorod particles has been used to immobilize glucose oxidase by glutaraldehyde. The polyaniline/gold nanorod composite structure gave an excellent matrix for enzyme immobilization due to the large specific surface area and higher electroactivity. The composite has been characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), and surface-enhanced Raman spectroscopy (SERS). The SERS spectrum of the surface-immobilized glucose oxidase and the spectrum of the native enzyme indicate that the main feature of the native structure of glucose oxidase was conserved after being immobilized on the polymer matrix. The amperometric response was measured as a function of concentration of glucose at a potential of 0.6 V versus Ag/AgCl in 0.1 M phosphate buffer at pH 6.4. Linear range of the calibration curve was ...