Graphene field-effect transistors-based biosensors for Escherichia coli detection

Novel devices are desperately required for effective detection of bacteria because of its potential risks in the fields of food safety and public health. In this paper, we demonstrated graphene field-effect transistors (G-FETs) for Escherichia coli (E. coli) detection. Linker molecules and antibodies were employed to functionalize graphene. Raman spectroscopy and confocal microscopy were used to confirm the functionalization process of the linker molecules and antibodies. The linker molecule (1-pyrenebutanoic acid succinimidyl ester, PBASE) contains two parts: pyrene backbone and succinimidyl ester group. Pyrene attached onto the graphene surface via π-π stacking, and succinimidyl ester group covalently reacted with amino group of antibodies. Antibodies functionalized G-FETs enabled effective E. coli detection. The results showed that the Dirac point of the G-FETs shifted to right after detection of E. coli bacteria. Our G-FETs devices showed an obvious increase in the electrical current when the E. coli concentration was 5×103 CFU/mL. The simple and label-free biosensor reported here possesses promising potential to serve as a platform for other bacteria, protein and small molecule detection.