Amplified electrochemical immunoassay for 5-methylcytosine using a nanocomposite prepared from graphene oxide, magnetite nanoparticles and β-cyclodextrin.
Yunlei ZhouWenjing JiangHanwen WuFei LiuHuanshun YinNan LuShiyun AiPublished in: Mikrochimica acta (2019)
A nanocomposite was prepared from β-cyclodextrin (β-CD) functionalized graphene oxide and magnetic nanoparticles (GO/Fe3O4/β-CD). In parallel, a polyamidoamine dendrimer conjugated to avidinylated alkaline phosphatase (PAMAM-avidin-ALP) was prepared and exploited as a signal amplification unit in a voltammetric immunoassay for 5-methylcytosine (5mC) in genomic DNA. The GO/Fe3O4/β-CD as a substrate material exhibited good solubility, electrical conductivity and large surface. This is beneficial for the further modification of antibodies (Ab) by host-guest interaction and amide bonds. By taking advantage of three-dimensional structure to capture avidin-ALP by amide linkages, PAMAM was used as a catalytic signal amplification element in this assay. Under the optimized condition and at a typical working potential of 0.94 V, the response to 5mC is linear in the 0.01-50 nM concentration range with a detection limit of 3.2 pM (at S/N = 3). The method is stable, selective and reproducible. It was applied to the determination of 5mC in genomic DNA of human tissue. Graphical abstract An electrochemical immunoassay was constructed for 5-methylcytosine detection based on nanocomposite of graphene oxide, magnetite nanoparticles and β-cyclodextrin, and enzymatic signal amplification.
Keyphrases
- label free
- reduced graphene oxide
- molecularly imprinted
- nucleic acid
- solid phase extraction
- quantum dots
- magnetic nanoparticles
- ionic liquid
- circulating tumor
- gold nanoparticles
- sensitive detection
- capillary electrophoresis
- photodynamic therapy
- cell free
- single molecule
- copy number
- nk cells
- carbon nanotubes
- gene expression
- mass spectrometry
- particulate matter
- hydrogen peroxide
- dna methylation
- high throughput
- visible light
- loop mediated isothermal amplification
- nitric oxide
- high resolution
- polycyclic aromatic hydrocarbons
- genome wide
- liquid chromatography