Electrochmistical Detection Research Based On Nucleic Acid

In this paper, we fabricated two electrochemical DNA sensors based on functional nucleic acid to detect bleomycins and special DNA sequence successfully. Bleomycins are widely used for the treatment of many types of cancers. There are some fatal side effects in the clinical application of bleomycins, such as pulmonary fibrosis. Therefore, to make full use of therapeutic efficacy and to weaken its toxicity, we proposed a simple, rapid, and convenient electrochemical method to detect trace bleomycins. A reported DNA was employed as substrate for bleomycins, it self-assembled on the gold electrode to fabricate an electrochemical DNA sensor, and the other terminus of this DNA labeled with ferrocenyl moiety as a signal reporter to arise remarkable faradaic current. In the presence of Fe(â…¡)-BLMs, the DNA on the gold electrode will occur the irreversible cleavage event, as a result, current peak decreases significantly. This designed sensor can detect bleomycins as low as 100 pM (0.293 ng/mL), more importantly, the sensor exhibits a good performance as well as in serum sample.Exonuclease III specifically recognizes duplex DNAs in the direction from 3'to 5' terminus. Taking advantage of exonucleaseâ…¢-aided, we designed a target recycling electrochemical DNA sensor to achieve special DNA sequence detection, with [Ru(NH3)6]3+ as a signal reporter. In the presence of target DNA, Exonuclease III selectively digests the signaling probe, leading to the digestion of a large amount of signaling probes gradually. The detection limit is as low as 20 fM. Moreover, this electrochemical DNA sensor has differentiation ability for single mismatches, with fairly good stability. We also demonstrate that Exonuclease III do not have activity for the duplex DNAs with 3'-overhang of> 4 bases and single-strand DNA.