Electrochemical nano-biosensors and measurements for direct DNA oxidation (Based on Nano-Microelectronics) (Educational-Research Ph.D.)
Researcher and author: PhD student Afshin Rashid
Note: Signal measurement Electrochemical methods are very useful for detecting direct DNA oxidation because electrochemical reactions directly generate an electronic signal and therefore do not require expensive converter devices.
In addition, since the order of the immobilized match can only be limited to a series of electrode substrates, the act of tracing is performed by a cheap electrochemical analytical series. Electrochemical sensors are used for clinical or environmental tests; the basis of the sensitivity of electrochemical signals to direct oxidation or catalyzing of DNA is also the reaction of molecules reporter or enzyme resuscitation. There are various methods used for electrochemical signal measurement . The basis of the signal measurement in direct electrochemical DNA is based on the oxidation and redox reaction of DNA at a mercury electrode, so the amount of oxidized and resuscitated DNA is proportional to the amount of DNA hybridized to the probe. In addition to the traditional methods of direct DNA reduction, a method called Stripping Adsorption Voltammetry is used to directly oxidize DNA, which is a very sensitive method. In the direct-electrochemical purine electrochemical method, they are oxidized by materials such as carbon, indium oxide (ITO) gold, and polymer-coated electrodes. Although the direct electrochemical method is very sensitive, its application is complex because direct oxidation of DNA requires high potential field current. Advanced numerical and numerical methods are also needed to measure each signal. Of course, new methods have been designed that can be eliminated by the physical interference methods created in the field.
The target DNA is tracked by probes fixed on magnetic beads. In this method, after the probe's DNA hits the target DNA, the magnetic beads are separated in solution. The DNAs are collected in acidic solution and the guanine and adenine-free nucleosides are collected and analyzed by absorption voltammetry . A similar method has also been reported using direct oxidation of guanine, which was able to detect a specific mutation among the DNA fragments amplified by PCR. Another method is to use a peptide nucleic acid probe that performs more hybridization with these probes and can detect point mutations in the target DNA by this method.The indirect electrochemical method of DNA is used to oxidize DNA using electrochemical intermediates. One particularly effective method is the use of polypyridyl (RUII) and IIO complexes by which their molecules undergo electrochemical oxidation of guanine. With this method, the researchers were able to detect a three-nucleotide sequence. This method, together with PCR-rt, can be used to overexpress genes in tumor specimens and is highly sensitive. In this method, the organic bases that are chemically modified are introduced into the PCR product and the DNA is extracted from the probes. Although this is a very sensitive method , it is not yet fully understood as it is suitable for clinical diagnosis. One of the benefits of this method is its non-complexity.
Several methods have been used to detect the target DNA with the reporter molecules with the labeled active molecule. By physical methods, the tagged sequence can be restricted to the extent that the assay consists of assay sandwich component Three, in which case the resuspended tagged material binds to a synthetic DNA fragment that binds this DNA fragment. Connects to the probe-target complex In other words, the resuscitated tag material binds to a synthetic fragment that binds or hangs to the probe-target complex, in which case the target DNA needs to be modified. Creates the elimination, causing the probe and sequence of tag matches to be put together. Marked probes use a probe labeled with ferrosin on the gold electrode. Using this technique can be encapsulated DNA target and back to the effect is to change the face Frvsyn molecules that signal to the gold electrode and the signal stream is measured in farads.
Author: Engineer Afshin Rashid
PhD student of Nano-Microelectronics at Islamic Azad University, Science and Research Branch, Tehran