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.

Hu R ，Wen W ，Wang Q ，Xiong H ，Zhang X ，Gu H ，Wang S ... -  《-》

A simple and sensitive impedimetric aptasensor for the detection of tumor markers based on gold nanoparticles signal amplification.

A simple and sensitive electrochemical impedimetric aptasensor based on gold nanoparticles (AuNPs) signal amplification was developed for the ultrasensitive detection of tumor markers (mucin 1 protein, MUC1 as a model). The designed cDNA, which is partly complementary with the aptamer of MUC1 was immobilized on the gold electrode. The detection of MUC1 could be carried out by virtue of switching structures of aptamers from DNA/DNA duplex to DNA/target complex. The change of the interfacial feature of the electrode was characterized by electrochemical impedance analysis (EIS) with the redox probe [Fe(CN)6](3-/4-). The quantitative detection of MUC1 protein was obtained from the changes of electron-transfer resistance (ΔRet). Moreover, as the signal enhancer, the aptamer-modified AuNPs (Apt@AuNPs) conjugates was introduced on the electrode by the hybridization of cDNA with aptamer. As expected, the detection sensitivity for MUC1 was greatly improved, which may be due to the specific binding of MUC1 onto the surface of the Apt@AuNPs modified electrode. This proposed simple aptasensor has a low detection limit of 0.1 nM, and also exhibits several advantages of high sensitivity and good selectivity. This present work may provide a general model for the detection of tumor marker based on impedimetric aptasensor.

Liu X ，Qin Y ，Deng C ，Xiang J ，Li Y ... -  《-》

Increased electrocatalyzed performance through hairpin oligonucleotide aptamer-functionalized gold nanorods labels and graphene-streptavidin nanomatrix: Highly selective and sensitive electrochemical biosensor of carcinoembryonic antigen.

We report a triplex signal amplification strategy for sensitive biosensing of cancer biomarker by taking advantage of hairpin-shaped oligonucleotide-functionalized gold nanorods (HO-GNRs), graphene and the avidin-biotin reation. The strategy expands electrochemical detection of carcinoembryonic antigen (CEA) by using an aptamer as biosensor's recognition element and HO-GNRs as signal enhancer. To construct this biosensor, the GNR was used as a carrier of horseradish peroxidase (HRP) and HO aptamer with a biotin at the 3'-end and a thiol at the 5'-end, which amplified the electrochemical response because of a large molar ratio of HRP to HO. In the presence of target CEA, the binding reactions of CEA with the loop portions of the HOs caused HOs' loop-stem structure opened and exposed the biotins, and then HRP-GNRs-HO conjugates were captured on graphene and streptavidin modified electrodes via the reaction between the exposed biotins and preimmobilized streptavidins. The accumulation of HRP effectively catalyzed the hydrogen peroxide-mediated oxidation of o-phenylenediamine to generate an electrochemical reduction current for CEA detection. Under optimal conditions, the electrochemical biosensor exhibited a wide dynamic range of 5pgmL(-1) and 50ngmL(-1) toward CEA standards with a low detection limit of 1.5pgmL(-1) (signal-to-noise ratio of 3). The proposed biosensor accurately detected CEA concentration in 8 human serum samples from patients with lung diseases, showing excellent correlations with standard chemiluminescence immunoassay. Furthermore, these results of target DNA detection made it abundantly clear that the proposed strategy can also be extended for detection of other relative biomarkers using different functional DNA structures, which shows great prospects in single-nucleotide polymorphisms analysis, biomedical sensing and application for accurate clinical diseases diagnostic.

Wen W ，Huang JY ，Bao T ，Zhou J ，Xia HX ，Zhang XH ，Wang SF ，Zhao YD ... -  《-》

Dual amplification strategy of highly sensitive thrombin amperometric aptasensor based on chitosan-Au nanocomposites.

Zhao J ，Lin F ，Yi Y ，Huang Y ，Li H ，Zhang Y ，Yao S ... -  《-》

Highly sensitive electrochemical label-free aptasensor based on dual electrocatalytic amplification of Pt-AuNPs and HRP.

Bai L ，Yuan R ，Chai Y ，Yuan Y ，Mao L ，Zhuo Y ... -  《-》