title: Rapid electrochemiluminoimmunoassay of human C-reactive protein at planar disposable oxide-coated silicon electrodes.
abstract: Electrochemiluminescence (ECL) of aromatic Tb(III) chelates at thin insulating film-coated electrodes provides a means for extremely sensitive detection of Tb(III) chelates and also of biologically interesting compounds if these chelates are used as labels in bioaffinity assays. The suitability of silicon electrodes coated with thermally grown silicon dioxide film as disposable working electrodes in sensitive time-resolved ECL measurements is demonstrated, and a rapid electrochemiluminoimmunoassay (ECLIA) of human C-reactive protein (hCRP) is described. Tb(III) chelate labels can be detected almost down to picomolar level, and the calibration curve of these labels covers more than 6 orders of magnitude of chelate concentration. The calibration curve of the present immunometric hCRP assay was found to be linear over a wide range, approximately 4 orders of magnitude of hCRP concentration, the detection limit of the protein being 0.3 ng mL(-1) (mean background + 2SD) on CV values of about 10-30%, depending on the immunoassay incubation time. In the ECLIA measurements, different incubation times were tested from 15 min (giving above-mentioned performance) to as short as only 2 min, which still gave successful results with approximately 20,000 times better detection limit levels than traditional commercial assay methods. During the ECLIA process, also the Si electrode surface morphology was also investigated by atomic force microscope monitoring.
authors.affiliation: Department of Chemistry, University of Turku, FIN-20014 Turku, Finland. timo.ala-kleme@utu.fi
authors.forename: Timo
authors.initials: T
authors.lastname: Ala-Kleme
authors.forename: Piia
authors.initials: P
authors.lastname: Mäkinen
authors.forename: Tiina
authors.initials: T
authors.lastname: Ylinen
authors.forename: Leif
authors.initials: L
authors.lastname: Väre
authors.forename: Sakari
authors.initials: S
authors.lastname: Kulmala
authors.forename: Petri
authors.initials: P
authors.lastname: Ihalainen
authors.forename: Jouko
authors.initials: J
authors.lastname: Peltonen
mesh_terms: D015374:Biosensing Techniques; D002097:C-Reactive Protein / Q000032:analysis*; D004563:Electrochemistry; D006801:Humans; D007118:Immunoassay; D017736:Ion-Selective Electrodes; D008163:Luminescent Measurements; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D012825:Silicon; D013725:Terbium / Q000737:chemistry
chemical_list: D010087:Oxides; D013725:Terbium; D002097:C-Reactive Protein; D012825:Silicon