title: A quantitative relaxometric version of the ELISA test for the measurement of cell surface biomarkers.
abstract: Quantitative measurement of marker expression in diseased cells is still a topic of considerable interest and different methodologies are currently under intense scrutiny. This work aims at developing an in vitro diagnostic method based on the release of paramagnetic species from relaxometrically "silent" liposomes operated by the action of a phospholipase A2 (PLA2) previously targeted to the epitope of interest. The released paramagnetic species causes an increase of the longitudinal water proton relaxation rate proportional to the number of PLA2 bound to the cell outer surface. The sensitivity of the herein proposed method, named R-ELISA, was attempted in the detection of folate receptor expression on human ovarian cancer cells by functionalizing PLA2 with folic acid. Receptor/cell number of 8.3×10(5) has been measured on IGROV-1 cells. The R-ELISA assay can detect nanomolar cell suspension receptor concentrations and has been validated by well-established spectrofluorimetric procedures.
authors.affiliation: Department Molecular Biotechnology and Health Sciences, Institution University of Torino, Address via Nizza 52, Torino (Italy).
authors.forename: Diego
authors.initials: D
authors.lastname: Alberti
authors.forename: Mark
authors.initials: M
authors.lastname: van't Erve
authors.forename: Rachele
authors.initials: R
authors.lastname: Stefania
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Ruggiero
authors.forename: Marta
authors.initials: M
authors.lastname: Tapparo
authors.forename: Simonetta
authors.initials: S
authors.lastname: Geninatti Crich
authors.forename: Silvio
authors.initials: S
authors.lastname: Aime
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006801:Humans; D010051:Ovarian Neoplasms / Q000737:chemistry* / Q000378:metabolism*; D054467:Phospholipases A2 / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; D054467:Phospholipases A2
keywords: NMR spectroscopy; analytical methods; paramagnetic liposomes; personalized medicine; relaxometry