Experimental Studies Of Electrochemical Biosensors Modifiedby AuNP/ERGO@CNT For Detecting MDR1 And ABCB1

Electrochemical biosensors as a new type of chemical sensors, developed by using the molecular probes which have a selective recognition to specific substances, its advantages are novel configuration, skilled design and diversal use. Nanomaterials has unique physical and chemical properties, for example, its higher specific surface area, excellent electrical conductivity and efficient catalytic performance and good biological compatibility. Nanomaterials introduced to in the field of electrochemical biosensors, can significantly improve the sensitivity, selectivity and stability of the sensor.This paper constructed a new type of nanoelectrochemical biosensors based on the preparation of gold nanoparticles/graphene@carbon nanotube nanocomposite, and used to detect multi-drug resistance gene(MDR1) and its expression protein(ABCB1). This sensor’ specificity, sensitivity, stability and performance are also investigated. In the paper, the main contents described as follow:The first part: by "one-step" electrochemical reduction method, the gold nanoparticular /graphene@carbon nanotubes nanocomposites(AuNP/ERGO@CNT) was prepared. Then a nano-electrochemical DNA biosensor based on this nanocomposite modified glassy carbon electrode(GCE), And, the MDR1 probe was covalently assembled onto the AuNP/ERGO@CNT/GCE via Au-S bond,,and then the new “sandwich” structure nano electrochemical DNA sensors was fabricated for detection of multi-resistant MDR1 gene. The experimental result revealed that the builted new nano electrochemical DNA sensors can betterly identify the completely complementary, single-base mismatch and completely wrong sequence in the hybrid solution. Under the optimal hybridization condition, the concentration of MDR1 gene and test response signal had a good linear relationship within the scope of 5.0×10-15-1.0×10-12 mol/L, and the detection limit is 3.2×10-16 mol/L. Then the anti-interference ability of the sensor was investigated through the simulation experimental samples, and the results showed that the constructed sensor also can distinguish belong good complementary completely, single-base mismatch and completely mismatch sequences in blood serum, and had a good linear relationship in 5.0×10-15-1.0×10-12 mol/L with the detection limit of 6.3×10-16 mol/L. So that the builted new nano DNA electrochemical sensor has the advantages of good specificity, high sensitivity, good stability, reproducibility and anti-interference ability, and was possible to realize the qualitative and quantitative detection of MDR1 gene.The second part: With marker protein amino activation of biotin(BNHS), the biotin will be connected to the submember of the family, 1 B transporters which from the MDR1 gene expression product, ATP combination box(ABCB1). The AuNP/ERGO@CNT/GCE electrode was prepared by the "one-step" electrochemical reduction. Then using the interaction between proteins and gold, combined with the immune response competition, the electrochemical immunosensor was constructed for detecting ABCB1 proteins. In the optimal experimental conditions, the detection electrical signal of the sensor had a good linearity with the ABCB1 protein concentration logarithm in 0.5~100 ng/mL, and the detection limit is 0.09 ng/mL. Experimental results showed that the constructed new type nanostructured electrochemical immunosensor can well distinguish the ABCB1 protein from other associated tumor protein, this biosensor also has a good stability and reproducibility.