title: Carbon nanotube microwell array for sensitive electrochemiluminescent detection of cancer biomarker proteins.
abstract: This paper describes fabrication of a novel electrochemiluminescence (ECL) immunosensor array featuring capture-antibody-decorated single-wall carbon nanotube (SWCNT) forests residing in the bottoms of 10-μL wells with hydrophobic polymer walls. Silica nanoparticles containing [Ru(bpy)(3)](2+) and secondary antibodies (RuBPY-silica-Ab(2)) are employed in this system for highly sensitive two-analyte detection. Antibodies to prostate specific antigen (PSA) and interleukin-6 (IL-6) were attached to the same RuBPY-silica-Ab(2) particle. The array was fabricated by forming the wells on a conductive pyrolytic graphite chip (1 in. × 1 in.) with a single connection to a potentiostat to achieve ECL. The sandwich immunoassay protocol employs antibodies attached to SWCNTs in the wells to capture analyte proteins. Then RuBPY-silica-Ab(2) is added to bind to the captured proteins. ECL is initiated in the microwells by electrochemical oxidation of tripropyl amine (TprA), which generates excited state [Ru(bpy)(3)](2+) in the 100-nm particles, and is measured with a charge-coupled device (CCD) camera. Separation of the analytical spots by the hydrophobic wall barriers enabled simultaneous immunoassays for two proteins in a single sample without cross-contamination. The detection limit (DL) for PSA was 1 pg mL(-1) and for IL-6 was 0.25 pg mL(-1) (IL-6) in serum. Array determinations of PSA and IL-6 in patient serum were well-correlated with single-protein ELISAs. These microwell SWCNT immunoarrays provide a simple, sensitive approach to the detection of two or more proteins.
authors: Department of Chemistry (U-3060), University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, USA.
authors: Naimish P
authors: NP
authors: Sardesai
authors: John C
authors: JC
authors: Barron
authors: James F
authors: JF
authors: Rusling
mesh_terms: D055910:Antibodies, Immobilized / Q000737:chemistry / Q000276:immunology; D014408:Biomarkers, Tumor / Q000097:blood*; D056831:Coordination Complexes / Q000737:chemistry; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007118:Immunoassay / Q000379:methods*; D015850:Interleukin-6 / Q000097:blood / Q000276:immunology; D008163:Luminescent Measurements / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry; D037742:Nanotubes, Carbon / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D017430:Prostate-Specific Antigen / Q000097:blood / Q000276:immunology; D012413:Rubidium / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D055910:Antibodies, Immobilized; D014408:Biomarkers, Tumor; D056831:Coordination Complexes; D015850:Interleukin-6; D037742:Nanotubes, Carbon; D011108:Polymers; D012822:Silicon Dioxide; D017430:Prostate-Specific Antigen; D012413:Rubidium