Control of Metal Content in Polystyrene Microbeads Prepared with Metal Complexes of DTPA Derivatives
Jieyi Liu, Edmond C. N. Wong, Elsa Lu, Jonathan Jarzabek, Daniel Majonis, Mitchell A. Winnik
Abstract
Mass cytometry (MC) is an emerging analytical technique in which an inductively coupled plasma time-of-flight mass spectrometer is employed to analyze the signals of isotopic labels on cell and microbead samples. Bead-based applications in mass cytometry require one to label the microbeads with various metal ions that can be individually identified by MC. This paper describes a novel approach to encoding microbeads with controlled levels of metal ions by introducing polymerizable metal complexes of the structure M(DTPA-VBAm2) in two-stage dispersion polymerization reactions. Using this method, the incorporation of various metal ions is effective and consistent in the investigated concentration range. As a result, this method provides a convenient path for synthesizing microbeads with controlled metal content for mass cytometry applications. As a proof-of-concept experiment, a sample of europium-labeled microbeads was surface-functionalized with a goat anti-mouse IgG antibody and tested by mass cytometry for its ability to detect a Lu-labeled mouse IgG. Surface functionalization involved a thin silica shell to which neutravidin was covalently attached. This experiment demonstrates the potential use of these microbeads as classifier beads for bead-based assays in MC.