Glycoprotein biosensor boosted by signal amplification of heparin polysaccharide and insights into glycan-lectin...

Alpha-fetoprotein (AFP) is one representative glycoprotein tumor marker, which has served as a useful predictive and prognostic biomarker in clinical practice for hepatocellular carcinoma. Polymeric membrane ion-selective electrode (ISE) can be employed for sensing of bio-macromolecules. Commonly, ISE is operated under the zero-current potentiometry. In this work, a pulsed galvanostatic chronopotentiometric measurement mode was established to enable the bio-sensing of AFP glycoprotein, boosted by a signal amplification of employing heparin polysaccharide as an indicator ion of multi-charge and large-volume. A synergistic effect of the electro-enhanced mass transfer and polyionic amplification was shown to be superior and unmatched by indicator ions of single-charge and small-volume. Specifically, this work achieved the sensitive and specific bio-sensing of AFP glycoprotein (with limits of detection down to 1.92 pg/mL and 4.10 fg/mL for concanavalin A-based ISE and antibody-based ISE, respectively). Good selectivity, reproducibility, and repeatability were demonstrated for the fabricated ISEs. Spiking experiments in both mouse and human serum afforded excellent recoveries, exhibiting that both lectin-and antibody-functionalized ISEs were capable in glycoprotein assay within complex matrices. More significantly, this work evaluated the lectin and antibody's bio-recognition abilities for the same glycoprotein target, transducing the difference of bio-recognition processes to potentiometric signals for display.