Abstract
An electrochemical DNA nanobiosensor was prepared by immobilization of a 20mer thiolated probe DNA on electro-deposited generation 4 (G4) poly(propyleneimine) dendrimer (PPI) doped with gold nanoparticles (AuNP) as platform, on a glassy carbon electrode (GCE). Field emission scanning electron microscopy results confirmed the co-deposition of PPI (which was linked to the carbon electrode surface by C-N covalent bonds) and AuNP ca 60 nm. Voltammetric interrogations showed that the platform (GCE/PPI-AuNP) was conducting and exhibited reversible electrochemistry (E°′ = 235 mV) in pH 7.2 phosphate buffer saline solution (PBS) due to the PPI component. The redox chemistry of PPI was pH dependent and involves a two electron, one proton process, as interpreted from a 28 mV/pH value obtained from pH studies. The charge transfer resistance (Rct) from the electrochemical impedance spectroscopy (EIS) profiles of GCE/PPI-AuNP monitored with ferro/ferricyanide (Fe(CN)63-/4-) redox probe, decreased by 81% compared to bare GCE. The conductivity (in PBS) and reduced Rct (in Fe(CN)63-/4-) values confirmed PPI-AuNP as a suitable electron transfer mediator platform for voltammetric and impedimetric DNA biosensor. The DNA probe was effectively wired onto the GCE/PPI-AuNP via Au-S linkage and electrostatic interactions. The nanobiosensor responses to target DNA which gave a dynamic linear range of 0.01 - 5 nM in PBS was based on the changes in Rct values using Fe(CN)63-/4- redox probe.
Highlights
A biosensor is an analytical device that incorporates a bioreceptor onto a transducer surface and in the presence of an analyte, produces measurable signals that are proportional to the analyte concentration
The charge transfer resistance (Rct) from the electrochemical impedance spectroscopy (EIS) profiles of glassy carbon electrode (GCE)/PPI-AuNP monitored with ferro/ferricyanide (Fe(CN)63-/4-) redox probe, decreased by 81% compared to bare GCE
Generation 4 (G4) poly(propyleneimine) dendrimer was purchased from SyMO-Chem, Eindhoven, Netherlands
Summary
A biosensor is an analytical device that incorporates a bioreceptor onto a transducer surface and in the presence of an analyte, produces measurable signals (due to a bio-recognition event) that are proportional to the analyte concentration. Biosensors exploit the excellent selectivity, specificity and reactivities of immobilized biomaterials towards their substrates They are relatively less expensive, faster, more user friendly and miniaturizable, compared to traditional instrumental methods. Lucarelli et al [8] and Sassolas et al [22] demonstrated in their studies how the functionalization of oligonucleotides improves their immobilization chemistry and the performance of DNA biosensors. The functionalization of both the immobilization platform and the DNA will be performed with the aim of improving the biosensor response characteristics. This involves the use of GCE modified with dendrimeric materials that are doped with gold nanoparticles. This paper describes the preparation and electrochemical responses of a DNA nanobiosensor consisting of AuNP-doped PPI and thiolated 20mer oligonucleotide immobilized on a GCE
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
