Electrochemical Investigation of Oligonucleotide-DNA Hybridization on Poly(4-Methoxyphenethylamine)

Abstract

This work describes the immobilization of purine and pyrimidine bases and immobilization/hybridization of synthetic oligonucleotides on graphite electrodes modified with poly(4-methoxyphenethylamine) produced in acid medium. The immobilization of adenine, guanine, cytosine and thymine on these modified electrodes was efficient, producing characteristic peaks. Another relevant observation is that, according to the literature, pyrimidine bases, cytosine and thymine are more difficult to detect. However, when immobilized onto the poly(4-methoxyphenethylamine), a significant increase in the magnitude of the current was obtained. The observation of the hybridization between the poly(GA) probe and its complementary, poly(CT) target, was possible by monitoring the guanosine and adenosine peaks or through methylene blue indicator, using differential pulse voltammetry. Hybridization results in a decrease of the peak current of guanosine and adenosine or the signal of methylene blue accumulated on the modified electrode surface. The hybridization with the complementary target was also investigated by electrochemical impedance spectroscopy. The results showed a significant modification in the Nyquist plot, after addition of the complementary target, with increase of the charge transference resistance.

A promising bioelectrode based on gene of Mycobacterium leprae immobilized onto poly(4‐aminophenol)

“…This is justified by helix formation of the double strand DNA, with a significant change in the flexibility and size of the DNA, increasing the distance of the double strand formed with the electrode surface, due to the lower conformational flexibility, resulting in decrease of the charge transfer. Similar effect was observed in assays with synthetic oligonucleotides, using methylene blue as indicator 18…”

“…4(A,B)). Moreover, the hybridization increases the distance between the dsDNA/mediator and the electrode, decreasing the electron transfer 18, 25…”

“…Our group has carried out studies aiming the development of electrodes modified with polymers derived of phenols and ethers, to immobilization of biomolecules 10–12, 16–18…”

A novel polymer‐based genosensor for the detection and quantification of Streptococcus pneumoniae in genomic DNA sample

“…This phenomenon occurs due to the fact that single‐stranded DNA presents higher degree of adsorption and high proximity at the electrode surface, due to its higher conformational flexibility, favoring the charge transfer between probe and the surface electrode. After hybridization, hydrogen bonds are formed between complementary sequences, leading to a duplex, which is more difficult to oxidize the bases .…”

“…Electrochemical DNA sensing bears advantages as fast response time, high sensitivity, and low cost . This technique employs immobilized DNA sequences on the sensor surface as a recognition element and the sequence‐specific hybridization can be monitored and analyzed . The hybridization signal can be either directly detected (by monitoring the DNA oxidation or reduction process) or indirectly detected (using an indicator of the hybridization) .…”