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We demonstrate a multivalent recognition and highly selective aptamer signal amplification strategy for electrochemical cytosensing and dynamic cell surface N-glycan expression evaluation by the combination of concanavalin A (Con A), a mannose binding protein, as a model, conjugated poly(amidoamine) dendrimer on a chemically reduced graphene oxide (rGO–DEN) interface, and aptamer- and horseradish peroxidase-modified gold nanoparticles (HRP–aptamer–AuNPs) as nanoprobes. In this strategy, the rGO–DEN can not only enhance the electron transfer ability but also provide a multivalent recognition interface for the conjugation of Con A that avoids the weak carbohydrate–protein interaction and dramatically improves the cell capture efficiency and the sensitivity of the biosensor for cell surface glycan. The high-affinity aptamer- and HRP-modified gold nanoparticles provide an ultrasensitive …