Epitaxial graphene immunosensor for human chorionic gonadotropin

Abstract

Human chorionic gonadotropin (hCG), a 37 kDa glycoprotein hormone, is a key diagnostic marker of pregnancy and has been cited as an important biomarker in relation to cancerous tumors found in the prostate, ovaries and bladder.A novel chemically-modified epitaxial graphene diagnostic sensor has been developed for ultrasensitive detection of the biomarker hCG. Multi-layer epitaxial graphene (MEG), grown on silicon carbide substrates, was patterned using electron beam lithography to produce channel based devices. The MEG channels have been amine terminated using 3-Aminopropyl-triethoxysilane (APTES) in order to attach the anti-hCG antibody to the channel.Detection of binding of hCG with its graphene-bound antibody was monitored by measuring reduction of the channel current of the graphene biosensor. The sensitivity of the sensor device was investigated using varying concentrations of hCG, with changes in the channel resistance of the sensor observed upon exposure to hCG. The detection limit of the sensor was 0.62 ng/mL and the sensor showed a linear response to hCG in the range 0.62 to 5.62 ng/mL with a response of 142 Ω/ng/mL. At concentrations above 5.62 ng/mL the sensor begins to saturate.

Immobilization of Antibodies and Enzymes on 3-Aminopropyltriethoxysilane-Functionalized Bioanalytical Platforms for Biosensors and Diagnostics

“…Of interest is the use of multilayer epitaxial graphene (MEG) for the detection of human chorionic gonadotropin (hCG). 254 MEG was grown on silicon carbide substrates and modified by the Fenton reaction to yield a hydroxylated MEG layer. It was functionalized with APTES and then bound to anti-hCG Ab by EDC-NHS chemistry to provide a LOD of 0.62 ng mL −1 and a linear range of 0.62− 5.62 ng mL −1 .…”

Core–shell gold–silver nanoparticles based impedimetric immunosensor for cancer antigen CA125

“…Lately, nanomaterials based electrochemical immunosensors have become popular since they offer enhanced biomolecule loading capacity to increase the dynamic range of measurements. The technique has been extended by employing various nano-architectured electrode surfaces for determination of several carcinoma biomarkers-CA125 [14,15], human epidermal growth factor receptor [16], human chorionic gonadotropin [17] to biomolecules-interleukin-6 [18] and inorganic molecules-dopamine [19] and okadaic acid [20]. The reports for impedimetric immunosensor for CA125 are limited.…”

Recent advances in electrochemical biosensing schemes using graphene and graphene-based nanocomposites

“…Anti-hCG antibody/multi-layer epitaxial graphene grown on silicon carbide substrates as electrode 0.62-5.62 ng mL À1 (0.62 ng mL À1 ) [212] Anti-cTnI antibody/carboxylated graphene/ Au electrode 1 pg mL À1 -1 ng mL À1 (0.1 pg mL À1 ) [213] Human serum albumin/GO/APTES-modified ITO electrode Based on detection of tumor cells 2.5 · 10 3 -1.6 · 10 5 cells mL À1 (800 cells mL À1 ) [230] Anti-b-lactoglobulin antibody/4-aminophenyl film/graphene-modified screen printed electrode 1 pg mL À1 -100 ng mL À1 (0.85 pg mL À1 ) [231] Tyrosine Phenoxy-derivatized dextran/GO/Au chip 1-20 lg mL À1 (0.39 lg mL À1 ) [232] Toxoplasma gondii antigen/AuNP/ polythionine/graphene-Nafion/GCE 0.0375-1.2 AU mL À1 2-18 AU mL À1 (8 AU mL À1 ) [233] Alanine aminotransferase Graphene field effect transistor 10-100 U L À1 [234] Cancer antigen 153 Anti-cancer antigen 153 Ab/GO/screenprinted carbon electrode 1 mU mL À1 -200 U mL À1 (0.28 mU mL À1 ) [235] IL-6 Anti IL-6 Ab/GO-polyaniline nanowires-CdSe QDs/GCE 0.5 pg mL À1 -10 ng mL À1 (0.17 pg mL À1 ) [236] Interferon c IFN-c binding aptamers/graphene/16-mercaptohexadecanoic acid-modified Au electrode 0.1-0.7 pM (0.065 pM) [237] Matrix metalloproteinase-2 (MMP-2)…”