A Quantitative Relaxometric Version of the ELISA Test for the Measurement of Cell Surface Biomarkers

Authors

  • Dr. Diego Alberti,

    1. Department Molecular Biotechnology and Health Sciences, Institution University of Torino, Address via Nizza 52, Torino (Italy)
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  • Dr. Mark van't Erve,

    1. Department Molecular Biotechnology and Health Sciences, Institution University of Torino, Address via Nizza 52, Torino (Italy)
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  • Dr. Rachele Stefania,

    1. Department Molecular Biotechnology and Health Sciences, Institution University of Torino, Address via Nizza 52, Torino (Italy)
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  • Dr. Maria Rosaria Ruggiero,

    1. Department Molecular Biotechnology and Health Sciences, Institution University of Torino, Address via Nizza 52, Torino (Italy)
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  • Dr. Marta Tapparo,

    1. Department Molecular Biotechnology and Health Sciences, Institution University of Torino, Address via Nizza 52, Torino (Italy)
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  • Dr. Simonetta Geninatti Crich,

    Corresponding author
    1. Department Molecular Biotechnology and Health Sciences, Institution University of Torino, Address via Nizza 52, Torino (Italy)
    • Department Molecular Biotechnology and Health Sciences, Institution University of Torino, Address via Nizza 52, Torino (Italy)===

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  • Prof. Silvio Aime

    1. Department Molecular Biotechnology and Health Sciences, Institution University of Torino, Address via Nizza 52, Torino (Italy)
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  • This research was performed in the framework of the EU COST Action TD1004, and supported by the University of Torino (code D15E11001710003 project: Innovative Nanosized Theranostic Agents), by MIUR (PRIN 2009235JB7), by Regione Piemonte (POR-FESR Asse I: ATHIMAG), and by Consorzio Interuniversitario di Ricerca in Chimica dei Metalli dei Sistemi Biologici (CIRCMSB).

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 8.3×105 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.

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