Organic electrochemical transistor for sensing of sialic acid in serum samples

Sialic acid usually locates at the terminal of glycoproteins and glycolipids on cell surface. Compared to normal cells, cancer cells generally express much more sialic acid residues, and the sialylation of cell surface proteins or lipids is related to the progression of tumors, which leads to high expression of serum sialic acid in cancer patients. This work used an organic electrochemical transistor as the sensing platform to design a simple and suitable device for sensitive and convenient detection of sialic acid level in serum samples. The transistor-based biosensor consisted of three typical drain/source/gate Au electrodes on a glass substrate and a polymer membrane to serve as conducting channel between source electrode and drain electrode. The gate electrode was modified with carboxylated multi-wall carbon nanotubes to covalently bind 3-aminobenzeneboronic acid, which specifically recognized sialic acid to change the effect gate voltage of the transistor, and thus produced the signal of drain-source channel current for sensitive detection of sialic acid ranging from 0.1 to 7 mM. The novel biosensor possessed excellent specificity for distinguishing normal and cancer people. The detection results of serum samples from lung cancer patients demonstrated the excellent performance of the transistor-based biosensor, showing the potential application in clinical diagnose.