Label-free and high-resolution protein/DNA nanoarray analysis using Kelvin probe force microscopy

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Using the scanning probe technique known as Kelvin probe force microscopy it is possible to successfully devise a sensor for charged biomolecules. The Kelvin probe force microscope is a tool for measuring local variations in surface potential across a substrate of interest. Because many biological molecules have a native state that includes the presence of charge centres (such as the negatively charged backbone of DNA), the formation of highly specific complexes between biomolecules will often be accompanied by local changes in charge density. By spatially resolving this variation in surface potential it is possible to measure the presence of a specific bound target biomolecule on a surface without the aid of special chemistries or any form of labelling. The Kelvin probe force microscope presented here is based on an atomic force microscopy nanoprobe offering high resolution (<10 nm), sensitivity (<50 nM) and speed (>1,100 µm s−1), and the ability to resolve as few as three nucleotide mismatches.

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Figure 1: A KPFM study of the binding of avidin and neutravidin to immobilized biotin.
Figure 2: KPFM signal resulting from perfectly complementary and perfectly non-complementary targets.
Figure 3: The KPFM tolerance of high scan speeds.
Figure 4: Characterization of the KPFM biological detector.
Figure 5: The ability of KPFM to detect DNA binding on small patterned features.


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This research was performed under an appointment to the Department of Homeland Security (DHS) Scholarship and Fellowship Program (A.K.S.), administered by the Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between the US Department of Energy (DOE) and DHS. ORISE is managed by Oak Ridge Associated Universities (ORAU) under DOE contract number DE-AC05-06OR23100. All opinions expressed in this paper are those of the authors and do not necessarily reflect the policies and views of DHS, DOE or ORAU/ORISE. This research was funded through the Packard Fellows Program (A.M.B.) from the David and Lucile Packard Foundation.

Author information

A.K.S. and A.M.B. conceived the experiments. A.K.S. designed and performed the experiments. A.K.S. and A.M.B. wrote the manuscript. Both authors discussed the results and commented on the manuscript.

Correspondence to Angela M. Belcher.

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The authors declare no competing financial interests.

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Sinensky, A., Belcher, A. Label-free and high-resolution protein/DNA nanoarray analysis using Kelvin probe force microscopy. Nature Nanotech 2, 653–659 (2007) doi:10.1038/nnano.2007.293

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