| With the rapid development of gene project, molecular diagnostic techniques have been improved in the past several decades. Among them, clear-cut analysis of gene sequence using electrochemical DNA biosensor has been developed fast in recent years. With the development of DNA synthesis technology and microelectronic technology, the progress of DNA biosensor became flawless. Electrochemical DNA biosensor is a novel kind of biosensor grown in recent years. It can change the existence of target DNA into electrical signal. Because of it advantages, such as high sensitivity, good specificity, low cost, easy operation, simplify and compatibility with other equipment and so on, the biosensor develops very fast and shows the far-reaching significance and application value for the study of clinical medicine and genetic engineering. Nucleic acid probe technology which is a frontline biological technology grown with the development of genetic project possesses the characters, such as high sensitivity, good specificity, high speed and accuracy and so on, and play a great role in biomacromolecules study, clinical disease diagnosis and therapy.Nanotechnology is a rising field developed based on interdisciplinary in the late 1980s and in the early 1990s, and its development opened up a new level of human understanding world. Thereinto, nano-material is an important pact in the nanotechnology and possesses surface effect, small size effect, quantum size effect and macroscopic quantum tunneling effect which make it show special characters in mechanics, electricity, magnetics, thermotics, optics, chemical activity. Carbon material is the hot spot in nano materials, such as fullerene, carbon nanotube and graphene and so on. Graphene is thirdly latest discovered as a'new pattern carbon material'. Graphene has the relative advantages such as large specific surface area, bigger adsorption function and faster electron transfer and electro-catalytic activity.In the paper, a graphene modified glassy carbon electrode (GCE) was prepared by electrochemical reduction of graphite oxide fixed on the surface of GCE and characterized using electrochemistry method. With methylene blue (MB) as electrical activity model molecules, the electro-catalytic function for MB of graphene modified glassy carbon electrode was studied. The results indicated that graphite oxide became grapheme through electrochemical reduction and graphene modified glassy carbon electrode was built successfully. The modified electrode showed good stability and maximum sensitization for the redox current of MB. The electro-catalytic function of the electrode was fine.On that basis, the graphene modified glassy carbon electrode was used for detection of acute promyelocytic leukemia (APL) PML/RARαfusion gene. The amino-group modified probe of APL PML/RARαfusion gene fragment was immobilized onto surface of the graphene modified GCE by coupling activating agent. With MB as a novel electrochemical indicator, artificial APL PML/RARαfusion gene fragment was measured by differential pulse voltammetry (DPV). The result indicated graphene nanomaterial showed good sensitization on the measurement signal of MB. The relationship between the reduction peak current of MB and the concentration of complementary strand was linear in the range of 5×10-10~2.5×10-9 mol/L. The detection limit had been estimated as 8×10-11 mol/L. At the same time, the characters of the biosensor, such as specificity and stability and so on, were investigated. The method is simple, good specificity and high sensitivity. This approach is promising to the detection of the real sample.
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