Highly selective and sensitive visualization and identification of glycoproteins using multi-functionalized soluble dendrimer.

Glycoproteins are the most important and complex group of posttranslational modifications known in proteins. Many clinical biomarkers and therapeutic targets in cancer are glycoproteins. However, the isolation of glyco-specific antibodies and their poor stability remains a significant challenge in analytical method and diagnostic development. In this work, for the first time, we present a technology for highly efficient and selective glycosylation analysis on membrane without the use of glyco-specific antibodies. This approach, termed Nanopoly-BAV, which uses polyamidoamine dendrimers multifunctionalized with boronic acid for specific binding to glycoproteins and with biotin groups for glycoproteins visualization. The Nanopoly-BAV confers femtomolar sensitivity, exceptional glycoprotein specificity and selectivity with as high as 100000 folds for glycoproteins over nonglycoproteins. This synthetic, robust and highly selective Nanopoly-BAV has a great potential to measure cell signaling events by clearly distinguishing actual glycosylation signals from protein expression changes with superior stability. This technique may provide a powerful tool to monitor cellular signaling pathways and discovering new signaling events.