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A Quantitative Relaxometric Version of the ELISA Test for the Measurement of Cell Surface Biomarkers
Author(s) -
Alberti Diego,
van't Erve Mark,
Stefania Rachele,
Ruggiero Maria Rosaria,
Tapparo Marta,
Geninatti Crich Simonetta,
Aime Silvio
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201310959
Subject(s) - folate receptor , receptor , chemistry , cell , epitope , biophysics , cell culture , in vitro , biochemistry , biology , cancer cell , antibody , immunology , cancer , genetics
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 A 2 (PLA 2 ) 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 PLA 2 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 PLA 2 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.