Lectin-based biosensor strategy for electrochemical assay of glycan expression on living cancer cells

In this article, we report a novel lectin-based biosensor for electrochemical assay of cancer-associated glycosylation by comparative study of mannose and sialic acid expression on normal and cancer cells derived from human lung, liver, and prostate. Using a sandwich format, high sensitivity and selectivity were achieved by combining the lectin-based biosensor with the {lectin−Au−Th} bioconjugates featuring lectin and thionine (Th) labels linked to gold nanoparticles (AuNPs) for signal amplification. The proposed strategy demonstrated that mannose exhibited high expression levels in both normal and cancer cells, while sialic acid was more abundant in cancer cells as compared to normal ones. The results were in good agreement with those from fluorescent microscopy studies. The differences in the two glycan expression indicated that sialic acid could serve as a potential biomarker for early cancer detection. The lectin-based biosensor was also successfully used to quantify cancer cells and evaluate the average amount of sialic acid on single cell surface, which could supply significant information on glycan functions in cancer progression. Overall, the lectin-based electrochemical biosensor provides an effective pathway to analyze glycan expression on living cells and may greatly facilitate the medical diagnosis and treatment in early process of cancer.