Fabricationof Ultrasensitive Electrochemical DNA Biosensors Based On Nanomaterials

With the further development in the field of gene diagnosis technology, the method to sense or detect ultralow concentration of specific sequence DNA targets by using simple and inexpensive analysis has become increasing improtant in the diagnosis of genetic diseases. In this work, we utilized nanomaterials specially gold-nanomaterial decorated electrodeto fabricateultrasensitive DNA electrochemical biosensors. The paper includesfollowingfourchaptersChapter I: A review about the principle technology, the present research situation of electrochemical DNA biosensor, and application of nanomaterials in DNA biosensor are given.Chapter II: An electrochemical DNA biosensor based on graphene-thionine composite(Au NPs-Thi) was fabricated. In the fabrication process, graphene increases the surface area and conductivity efficiently. Gold-nanomaterial decorated graphene were immobilized on the electrode through the Au-S binding. When target DNA were added,graphene-thionine composite can also hybridize, making thionine link to the surface of electrode. The peak current of thionine can be measured.The results indicated the this biosensor possess good sensitivity. What’s more, the contruction process of the biosensor was simple.Chapter III: We developed a sensitive DNA biosensor based on gold nanomaterials and graphene amplified signal. We utilized gold nanorods decorated graphene as sensing platform. In the same time, we employed reporter probe capped with Au NPs conjugates through Au-S binding to fabricate a “sandwich-type” DNA biosensor, realizing the detection for target DNA。The biosensor showed high sensitive with a detection limitof 0.035 fM, and exhibited excellent discrimination ability for single-base mismatched target DNA detection.Chapter Ⅳ:We fabricated an ultrasensitive electrochemical DNA biosensor based on polypyrrole decorated graphene sheet and horseradish peroxidase functionalized gold nanoparticles composite. The polypyrrole decorated graphene sheet was used as sensing platform. We also prepared an enzyme functionalized gold nanoparticles composite. In the presence of H2O2, the response signal from catalyzing reaction significantly increased. This DNA sensor exhibited good sensitivity with a detection limit of 3.5 aM. In addition, this DNA sensor showed good selectivity.