Novel electrochemical aptamer biosensor based on an enzyme-gold nanoparticle dual label for the ultrasensitive detection of epithelial tumour marker MUC1.

A novel platform based on a hairpin oligonucleotide (HO) switch, gold nanoparticles (AuNPs), and enzyme signal amplification for the ultrasensitive detection of mucin 1 protein (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 catalysing the oxidation of o-phenylenediamine by H2O2. The reaction product was 2,3-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. After the recognition between oligonucleotide and MUC1, biotin was exposed. Biotin, along with the conjugate, was captured by streptavidin onto the surface of modified electrode. Therefore, the detection of target MUC1 which 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 from 8.8 nM to 353.3 nM and a lower detection limit of 2.2 nM for MUC1. The proposed method provided a new electrochemical approach for the detection of MUC1.