Glycan-Matchmade Multivalent Decoration of Enzyme Labels for Amplified Electrochemical Detection of Glycoproteins

Glycoproteins are of significant value to liquid biopsy of human diseases. Herein, we present a universal electrochemical platform for the amplified detection of glycoproteins, taking advantage of the glycan-matchmade multivalent decoration of enzyme labels for the enzymatic signal amplification. Briefly, the glycan-matchmade multivalent decoration involves two steps, i.e., the site-directed decoration of the phenylboronic acid-coated gold nanoparticles (PBA-AuNPs) to the cis-diol-containing glycans of glycoproteins and the subsequent decoration of enzyme labels via the affinity cross-linking between the glycan moieties of enzyme labels and the remaining PBA groups on the PBA-AuNP cross-linkers. As the glycan matchmaking-based strategy enables the decoration of each glycoprotein with multiple enzyme labels, this electrochemical platform exhibits a high sensitivity toward glycoprotein detection. Using alkaline phosphatase (ALP) as the proof-of-concept enzyme label in combination with the solid-state voltammetric stripping assay of the enzymatically deposited metallic silver, the detection limits at the pg mL^-1 level have been obtained for the electrochemical aptamer-based detection of thrombin and prostate-specific antigen. Overall, this work illustrates an efficient and versatile strategy for the multivalent decoration of enzyme labels for electrochemical detection of glycoproteins at ultralow concentration levels, holding the desirable advantages of simplicity and cost-effectiveness over sandwich enzyme-linked immunosorbent assays.