Biorecognition element-free electrochemical detection of recombinant glycoproteins using metal-organic frameworks as...

Accurate and sensitive determination of recombinant glycoproteins is in great demand for the treatment of anemia-induced chronic kidney disease and the illegal use of doping agents in sports. In this study, an antibody and enzyme-free electrochemical method for the detection of recombinant glycoproteins was proposed via the sequential chemical recognition of hexahistidine (His₆) tag and glycan residue on the target protein under the cooperation interaction of nitrilotriacetic acid (NTA)-Ni²⁺complex and boronic acid, respectively. Specifically, NTA-Ni²⁺ complex-modified magnetic beads (MBs-NTA-Ni²⁺) are employed to selectively capture the recombinant glycoprotein through the coordination interaction between His₆ tag and NTA-Ni²⁺ complex. Then, boronic acid-modified Cu-based metal-organic frameworks (Cu-MOFs) were recruited by glycans on the glycoprotein via the formation of reversible boronate ester bonds. MOFs with abundant Cu²⁺ ions acted as efficient electroactive labels to directly produce amplified electrochemical signals. By using recombinant human erythropoietin as a model analyte, this method showed a wide linear detection range from 0.01 to 50 ng/mL and a low detection limit of 5.3 pg/mL. With the benefits from the simple operation and low cost, the stepwise chemical recognition-based method shows great promise in the determination of recombinant glycoproteins in the fields of biopharmaceutical research, anti-doping analysis and clinical diagnosis.