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. Author manuscript; available in PMC: 2015 Sep 1.
Published in final edited form as: Nat Nanotechnol. 2015 Feb 9;10(3):264–269. doi: 10.1038/nnano.2014.335

Fig. 1. Chemically-specific imaging and 3-D reconstruction using DNA labels.

Fig. 1

(a–c) A strand of DNA (probe) interacts with target DNA strands with shorter sequences. Sequences of target DNAs are complementary to different regions along the probe DNA (complementary sequences are given in identical colours). Formation of duplexes creates distinct force-time waveforms, which are detected by the twisting of T-shaped AFM cantilevers. The pulling forces exerted by the target molecules appear as negative peaks in the force-time waveforms. (d–f) Examples of experimentally measured waveforms corresponding to three cases in (a–c). Mapping the timing of pulling events across the sample surface allows locating specific chemical targets with high spatial-resolution (g) and reconstructing the 3-D locations of targets from their pairwise distances (h).