This paper presents an aptameric graphene nanosensor for detection of small-molecule biomarkers. To address difficulties in direct detection of small molecules associated with their low molecular weight and electrical charge, we incorporate an aptamer-based competitive affinity assay in a graphene field effect transistor (FET), and demonstrate the utility of the nanosensor with dehydroepiandrosterone sulfate (DHEA-S), a small-molecule steroid hormone, as the target analyte. In the competitive affinity assay, DHEA-S specifically binds to aptamer molecules pre-hybridized to their complementary DNA anchor molecules immobilized on the graphene surface. This results in the competitive release of the strongly charged aptamer from the DNA anchor and hence a change in electrical properties of the graphene, which can be measured to achieve the detection of DHEA-S. We present experimental data on the label-free, specific and quantitative detection of DHEA-S at clinically appropriate concentrations with an estimated detection limit of 44.7. nM, and analyze the trend observed in the experiments using molecular binding kinetics theory. These results demonstrate the potential of our nanosensor in the detection of DHEA-S and other small molecules in biomedical applications.
Bibliographical noteFunding Information:
We gratefully acknowledge financial support from the National Institutes of Health (Grant numbers 8R21GM104204 and 1DP3DK101085), the Raymond and Beverly Sackler Program at the Interfaces of Biophysical and Medical Sciences, the Chinese Academy of Sciences SAFEA International Innovation Teams program, and the International Scientific Collaborative Projects of Tianjin, China (Grant number 14RCGFGX00843). We would like to thank Dr. Kyung-Ae Yang for providing DHEA-S and aptamer samples and Professor Milan Stojanović for insightful comments. We also appreciate helpful discussions with and assistance from Timothy Olsen, Xiao Guo, Mirkó Palla and Wei Zhang. C.W. and Y.Z. acknowledge national scholarship awards from the China Scholarship Council ( Award numbers 201206200032 and 201206250034 ). G.H.L. acknowledges support from the Basic Science Research Program through the National Research Foundation of Korea (Grant number NRF-2014R1A1A1004632).
© 2015 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Biomedical Engineering