Biological Assembly Of Nanomaterials And Their Clinical Applications

It is well known that immunosensor, as a new detection device, has received greatattention during the past decades owing to its potential application in many field, such as foodindustry[1], biotechnology[2], pharmaceutical chemistry[3], environmental pollutant detection[4]and clinical diagnosis[5]. Specially, due to its excellent compatibility with miniaturizationtechnologies, simple instrumentation high sensitivity and specificity, electrochemicalimmunosensor, as a new analytical tools and instrumentation, has high compatibility withadvanced micromachining technologies for the detection of tumor markers in the clinicaldiagnosis.According to the related statistics, in the world, each year more than1million women arediagnosed with breast cancer. It is one of the most serious malignancies that harm to the healthof women. For breast cancer, the rapid, accurate diagnosis depends on the corresponding tumormarkers (Tumor marker, TM) rapid, accurate detection[6]. Serum Carbohydrate Antigen15-3(carbohydrate antigen15-3, CA15-3) is the clinical for breast cancer diagnosis and prognosis ofan important tumor marker[7]. Meanwhile, graphene, a new material for which the Noble prizewas won, has received increasing attention due to its unique physicochemical properties[8]. Inthis paper, we reported a kind of electrochemical immunosensor that based on graphene for theuncomplicated, rapid and ultrasensitive detection of CA15-3. On the one hand, the briefness notonly reflects in the easy fabrication of the immunosensor, but also exhibits the novel and easystrategy for the synthesis of the soluble reduced graphene oxide (rGO). On the other hand, thesensitivity of the immunosensor was improved by the large specific surface area of rGO sheetsto increase Ab loading. In addition, the electron transfer among base solution and the electrodewas immensely promoted by the high conductivity of rGO sheets. To fabricate theimmunosensor, rGO sheets was added onto glassy carbon electrode surface to form satble thinfilm with high electrochemical activity, then anti CA15-3antibody(Ab) was conjugated ontothe surface of rGO sheets by an amidation reaction between the carboxylic acid groups attachedto rGO sheets and the available amine groups of Ab[9]. The decrease of amperometric signal ofthe electrode resulted from the specific antibody-antigen immunocomplex form on theelectrode. The amperometric signal decreased linearly with CA15-3concentration in the range of0.05—10.00ng/ml with a low detection limit of6pg/ml. This immunosensor has manyadvantages such as good selectivity, stability and high sensitivity, therefore, this kind ofimmunosensor has a widely application for the ultrasensitive detection of tumor markers in theclinical diagnosis.In this paper, we fabricated a new electrochemical immunosensor for the detection ofalpha-fetoprotein (AFP) based on Au-Pd Rhombic Dodecahedra Nanoparticles and solublereduced graphene oxide (rGO) sheets for improving the sensitivity of the immunosensor.Briefly, owning to the excellent conductivity and large surface area of rGO sheets, primaryantibody-AFP (Ab1) is immobilized ontto the surface of soluble reduced graphene oxide(rGO)sheets via an amidation reaction between the carboxylic acid groups attached to rGO and theavailable amine groups of Ab1. The signal amplification strategy, using Au-Pd RhombicDodecahedra (RD) Nanoparticles as the label to increase the reduction ability of the NPstoward H2O2, improves the sensitivity and detection limit of the immunosensor. With primaryanti-AFP antibody (Ab1) immobilized onto rGO surface and secondary anti-AFP antibody (Ab2)absorded onto the Au-Pd RD NPs, the sandwich-type immunosensor exhibits a wide linearresponse to AFP ranging from0.05to30ng/mL,with a low detection limit of0.005ng/mL, goodstability and reproducibility. Simultaneously, this novel ultrasensitive immunosensor mayprovide many potential applications for the ultrasensitive detection of tumor markers in clinicaldiagnosis.