Novel fluoroimmunoassay for ovarian cancer biomarker CA-125.

Cancer antigen 125 (CA-125) is a glycoprotein biomarker that denotes the presence of ovarian and reproductive cancers in women, with serum concentrations of CA-125 greater than 35 U/ml considered indicative of potential malignancies. A fluorescent immunoassay recently developed in our laboratory employing the ALYGNSA antibody-orientation system has been used to measure CA-125 levels. This system displayed significantly increased sensitivity with a detection limit of 1.5 U/ml compared to that of a commercial CA-125 enzyme-linked immunosorbent assay (15 U/ml) This tenfold lower level of detection of the ALYGNSA CA-125 assay should permit better identification and monitoring of ovarian cancer.

Antibody orientation enhanced by selective polymer-protein noncovalent interactions.

A unique interaction has been found between protein G' (a truncated recombinant bacterial "alphabet" protein which aligns by noncovalent attachment to the antibody stem) and poly(methyl methacrylate), a thermoplastic polymer substrate, which can be easily fabricated using high-rate processes. Significantly improved orientation efficiency with traditional passive adsorption for this system (termed ALYGNSA) has been achieved as compared to the same assay performed on a polystyrene substrate with protein G'. Results were consistent with an average alignment of 80% of the human immunoglobulin G capture antibody which translated into a 30% to 50% improved alignment over an array of industry standards tested. Laser scanning confocal microscopy confirmed the immunological results. Studies of additional poly(methyl methacrylate) polymer derivatives and protein biolinker (A and AG) combinations have been conducted and have revealed different degrees of antibody alignment. These findings may lead to additional novel noncovalent methods of antibody orientation and greater sensitivity in immunological assays.