Sensitive, quantitative, and high-throughput detection of angiogenic markers using shape-coded hydrogel microparticles

Elevated serum concentrations of angiogenic markers including vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and platelet-derived growth factor (PDGF) have been correlated with various clinical disorders including cancer, cardiovascular diseases, diabetes mellitus, and liver fibrosis. In addition, the correlation between the serum concentrations of these factors, clinical diagnosis, prognosis, and response to therapeutic agents is significant. Thereby suggesting high-throughput detection of serum levels of angiogenic markers has important implications in early detection of different clinical disorders as well as for subsequent therapy monitoring. Here, we demonstrate the feasibility of utilization of shape-coded hydrogel microparticle based suspension arrays for quantitative and reproducible measurement of VEGF, FGF, and PDGF in single and multiplexed assays. Bio-inert PEG hydrogel attenuated the background signal thereby improving the sensitivity of the detection method as well as eliminating the need for blocking the proteins. In the singleplexed assay, the detection limits of 1.7 pg ml−1, 1.4 pg ml−1, and 1.5 pg ml−1 for VEGF, FGF, and PDGF respectively indicated that the sensitivity of the developed method exceeds that of the conventional technologies. We also demonstrated that in the multiplexed assays, recovery of the proteins was within 20% of the expected values. The practical applicability of the hydrogel microparticle based detection system was established by demonstrating the ability of the system to quantify the production of VEGF, FGF, and PDGF by breast cancer cells (MDA-MB-231).