(state 2). When erasing temperature (TE) was applied, it was split into two strands and

formed a hairpin structure again as temperature decreased (state 3). Keyser’s group re­

ported a different approach to DNA-based biomemory (Figure 17.3d) [14]. A short hairpin

DNA of eight base pairs (DATA) was attached along a double-stranded DNA called a DNA

carrier (Figure 17.3d). Then the DNA carrier carrying the DATA passed through a nanopore

acting as an electrode. The electrochemical signal read from the nanopores was different

depending on the structure of the DATA, so it was possible to know which DATA was

presented in the DNA carrier. As shown here, nucleic acids are an attractive material for

FIGURE 17.3

(a) A guanosine-based FET. Adapted with permission [ 11]. Copyright (2003) American Chemical Society. (b) A

ribozyme-based biologic gate Adapted with permission [ 12]. Copyright (2003) American Chemical Society. (c) A

DNA bioprocessor. Adapted with permission [ 13]. Copyright (2015) American Chemical Society. (d) A DNA

carrier-based biomemory device. Adapted with permission [ 14]. Copyright (2018) American Chemical Society.

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