Aptamers Based Electrochemical Biosensors For Detection Of MUC1

Protein is the material basis of life, is one of the important material composition and to maintain life activities, there would be no life without protein. Ultrasensitive assays for proteins play pivotal roles in the diagnosis of specific diseases in clinical application, basic discovery research and the improvement of proteomics. Mucins are a family of high molecular weight, heavily glycosylated proteins that are bound to cells by an integral transmembrane domain via the formation of a gel matrix. Mucinl is the first one to be found in mucin family which is a kind of mucous glycoprotein on the surface of cells. It’s has been researched on the expression of tumor and immune escape, usually thought of as a tumor associated antigen. Aptamers, which are artificial oligonucleotides in vitro selected through SELEX (systematic evolution of ligands by exponential enrichment) possess high affinity and high recognition ability for a wide array of targets, including drugs, proteins, carbohydrates, lipids, and other organic or inorganic molecules. They can be produced without the need for an animal source and can be synthesised and modified chemically with extreme accuracy at low cost. Furthermore, aptamers are thermally and chemically stable, are able to undergo several cycles of degeneration/renaturation without losing activity, and show good stability during long-term storage. Because of these advantages, aptamers have the potential to be as widely applicable as antibodies in biosensor applications and disease diagnosis.(1) A novel platform based on a hairpin oligonucleotide (HO) switch, gold nanoparticles (AuNPs), and enzyme signal amplification for the ultrasensitive detection of mucin1protein (MUC1) was developed in this assay. This HO aptamers and horseradish peroxidase (HRP) were immobilised on the AuNPs to yield HO-AuNP-HRP conjugates. AuNPs were used as labels and bridges between the HO and HRP. HRP was also used as label for catalyzing the oxidation of o-phenylenediamine by H2O2. The reaction product was2,3-diaminophenazine (DAP), which was reduced and could be detected at surface of modified electrode. The reduction signal of DAP was used as a probe for the sensitive detection. Therefore, the detection of target MUC1which was a membrane-associated glycoprotein of the mucin family could be sensitively transduced via detection of the electrochemical reduction signal of DAP. Compared to other aptasensors, this biosensor has a good linear correlation ranges from8.8nM to353.3nM and a lower detection limit of2.2nM for MUC1.(2) Exonuclease I (exoI) is selected to shear single-strand DNA specificity. We build a biosensor with catalytic cycle amplification of exoI. The targets MUC1compete with hybrid double chain. The double chain structure is broken with the recognition between MUC1and aptamer. Then exoI begin to shear single-strand aptamer which is combined with MUC1and release the target molecules involved in circulation amplification. This biosensor has a good linear correlation ranges from1.0×10-11～1.0×10-6mol L-1and a lower detection limit of4.0×10-12mol L-1.