Flow Cytometry-Assisted Mix-and-Read Assay for Ultrasensitive Detection of Protein Kinase Activity by use of Zr^sup 4+^-Functionalized Mesoporous SiO^sub 2^ Microspheres

A flow cytometry-assisted mix-and-read assay is developed for ultrasensitive detection of protein kinase activity by use of Zr4+-functionalized mesoporous SiO2 microspheres (ZrMMs). This strategy integrates the distinct advantages of ZrMMs for highly specific recognition as well as high capacity binding of kinase-induced fluorescent phosphopeptides and flow cytometry for powerful and separation-free bead analysis, leading to an ultrahigh sensitivity for kinase analysis in a extremely simple mix-and-read manner. Furthermore, this ultrasensitive design is well suitable for detection of cell kinase activities in complex biological samples and for screening of potential protein kinase inhibitors, which is of great significance for the development of targeted therapy, clinical diagnosis, and studies of cellular signal transduction pathways. [PUBLICATION ABSTRACT]