title: A novel immunosensor for detecting toxoplasma gondii-specific IgM based on goldmag nanoparticles and graphene sheets.
abstract: A novel electrochemical immunosensor for detecting toxoplasma gondii-specific IgM (Tg-IgM) was constructed based on goldmag (Au-Fe(3)O(4)) nanoparticles and graphene sheets (GS). Thionine (Thi), as a mediator, was first electropolymerized on a nafion-GS (Nf-GS) modified electrode. Subsequently, gold nanoparticles (AuNPs) were attached onto the poly-thionine film through π-stacking interactions, and then were used to immobilize toxoplasma gondii antigen (Tg-Ag) for immunosensor fabrication. A sandwich-type immunoassay for Tg-IgM was performed using Au-Fe(3)O(4) labeled anti-IgM-horseradish peroxidase (HRP) as trace label. Electrochemical detection was carried out in the presence of H(2)O(2) as HRP substrate. Using Au-Fe(3)O(4) provided a simple, non-chemical damaging method for regeneration, and enhanced the HRP reduction ability toward H(2)O(2). The AuNPs/Thi/Nf-GS nanocomposite also had good conductivity and biocompatibility, which effectively improved the immunosensor sensitivity. Under optimal conditions, the immunosensor can detect Tg-IgM in two linear ranges from 0.0375 to 1.2 AU mL(-1) and from 2.0 to 18 AU mL(-1) with a detection limit of 0.016 AU mL(-1) (S/N=3). The immunosensor exhibited good reproducibility, stability, and selectivity as well.
authors.affiliation: Key Laboratory of Medical Diagnostics of Ministry of Education, Department of Laboratory Medicine, Chongqing Medical University, Chongqing 400016, PR China.
authors.forename: Shuting
authors.initials: S
authors.lastname: Jiang
authors.forename: Erhui
authors.initials: E
authors.lastname: Hua
authors.forename: Mo
authors.initials: M
authors.lastname: Liang
authors.forename: Bei
authors.initials: B
authors.lastname: Liu
authors.forename: Guoming
authors.initials: G
authors.lastname: Xie
mesh_terms: D055910:Antibodies, Immobilized / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D002138:Calibration; D004563:Electrochemistry; D004797:Enzyme-Linked Immunosorbent Assay; D004867:Equipment Design; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000737:chemistry; D006801:Humans; D007120:Immunochemistry; D007075:Immunoglobulin M / Q000032:analysis*; D007202:Indicators and Reagents; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles; D012015:Reference Standards; D014122:Toxoplasma / Q000276:immunology*
chemical_list: D055910:Antibodies, Immobilized; D007075:Immunoglobulin M; D007202:Indicators and Reagents; D006046:Gold; D006108:Graphite; D006735:Horseradish Peroxidase; D052203:Ferrosoferric Oxide