Multi-purpose electrochemical biosensor based on a “green” homobifunctional cross-linker coupled with PAMAM dendrimer grafted p-MWCNTs as a platform: application to detect α2,3-sialylated glycans and α2,6-sialylated glycans in human serum

Abstract

Sialylated glycans are crucial molecular targets for cancer diagnosis and clinical research. α2,3-Sialylated glycans and α2,6-sialylated glycans are the predominant sialic acids found in nature. Different expression of the quantity of glycans can result in development of different disease. However, there are no ideal methods for discriminating α2,3-sialylated glycans and α2,6-sialylated glycans. In this work, a multi-purpose biosensor is fabricated for sensitive detection of α2,3-sialylated glycans and α2,6-sialylated glycans. To improve the sensitivity of the biosensor, p-MWCNTs were integrated with PAMAM, as PAMAM has highly branched and abundant amino groups, providing a large available surface area for linking with other substances. To achieve distinguishable recognition, Maackia amurensis lectin (MAL) and Sambucus nigra agglutinin (SNA) were included. To facilitate the lectin fixation, PDITC, a kind of green homobifunctional cross-linker, was selected. Under optimized detection conditions, the linear range of detection for α2,3-sialylated glycans is 10 fg mL⁻¹ to 50 ng mL⁻¹ with a lower detection limit of 3 fg mL⁻¹, and the linear range of detection for α2,6-sialylated glycans is 10 fg mL⁻¹ to 50 ng mL⁻¹ with a detection limit of 3 fg mL⁻¹. This work not only provides a method for distinguishing detection of α2,3-sialylated glycans and α2,6-sialylated glycans, but also provides a reference for future clinical testing.