Sandwich-type biosensor for the detection of α2,3-sialylated glycans based on fullerene-palladium-platinum alloy and 4-mercaptophenylboronic acid nanoparticle hybrids coupled with Au-methylene blue-MAL signal amplification.

α2,3-sialylated glycans (α2,3-sial-Gs) are one of the significant tumour biomarkers for the early diagnosis of cancer. In this work, a neoteric sandwich-type biosensor was developed for detecting α2,3-sial-Gs using 4-mercaptophenylboronic acid (4-MPBA) to construct a novel molecular recognition system by the coordination of a boron atom of 4-MPBA to the amide group of Neu5Ac in the α2,3-sial-Gs structure. Amino-functionalized fullerene coupled with palladium-platinum bimetallic alloy nanocrystals (n-C-PdPt) was synthesized to modify the surface of a glassy carbon electrode (GCE) because the n-C nanomaterial affords a large surface area for the on-site reduction of bimetallic alloy nanoparticles and an excellent capacity for electron transfer. Abundant 4-MPBA were immobilized on the n-C-PdPt, since the 4-MPBA has the mercapto group can combine with PdPt alloy through strong adsorption. Maackia amurensis lectin (MAL) was covalently immobilized on Au-poly (methylene blue) (Au-PMB) acting as the signal amplification components, which was used to recognize the α2, 3-sial-Gs specifically like a second antibody linked on Au-PMB. The differential pulse voltammetry (DPV) current response of the biosensor in 5mL of PBS (0.1M, pH = 7.4) was recorded, and the proposed sandwich-type biosensor showed a wide linear range of 10 fg mL -100ngmL as well as, a low detection limit of 3fgmL (S/N = 3). Furthermore, the proposed method exhibited good recovery and stability, indicating its potential for use in clinical studies.