17.5 Nanomaterial-Assisted Nucleic Acid–Based Bioelectronic Devices

17.5.1 Biomemory

Nucleic acids are widely used in the development of biomemory due to their unique

binding ability and ease of incorporation into nanomaterials. Choi’s group developed a

resistive switching random access memory device using Cu²⁺-doped salmon DNA

(Cu²⁺-DNA) as a switching medium [44]. The chelated Cu²⁺ ions were intercalated

between DNA base pairs by electrostatically binding to the phosphate backbones of the

DNA during the doping process. By applying suitable electrical voltages, the resistance

value of the device was changed due to the migration of Cu²⁺ ions as “On state” and

“Off state” for demonstration of resistive switching functions. Additionally, DNA,

which has high biocompatibility and biodegradable characteristics, had the advantage

of being easy to interact with Cu²⁺ ions.

Chen’s group introduced two types of metal nanomaterials simultaneously to DNA for

the development of the resistive switching memory device [45]. In this research, the CuO

and AlNPs were assembled via DNA strands bridge, forming CuO-DNA-Al nano­

composites. Resistive switching characteristics were demonstrated via Al NPs that gen­

erated Al ions under an electric field (Al → Al³⁺ + 3e^‒), and Al ions moved, following

the direction of the applied electric field. In this device, DNA served as a channel for the

movement of Al ions, and the CuO stabilized the movement of Al ions. The developed

CuO-DNA-Al nanocomposites-based biomemory device presented the improved re­

sistive switching characteristics through the introduction of both CuO and Al. In addi­

tion, Wu’s group developed a layered graphene-DNA-based biomemristor device [46].

The graphene had different electronic conductivities depending on the vertical and

horizontal directions of the basal plane, and these special physical properties enabled the

demonstration of multistate resistive switching behaviors. Moreover, uniformly layered

DNA provided the stability and reliability of these behaviors. The developed bio­

memristor device showed multistate resistive switching behaviors as well as multibit

parallel logic operations.

In another study, Choi’s group developed a resistive switching device based on a het­

erolayer composed of carboxyl modified MoS2 and DNA (Figure 17.6a) [47]. The excellent

semiconducting behavior of MoS2 NPs enabled the realization of the resistive switching

function. An insulating layer composed of DNA showed high stability and insulating

properties, compared to RNA or protein, for the formation of conducting-insulating-

semiconducting layers to demonstrate the resistive property. The developed device showed

an electrical bi-stable state with a wide voltage range (−4.0 V to 4.0 V) and nonvolatile

stability. As such, the nucleic acid can serve as a template for fabricating nanostructures by

molecular self-assembly with high stability, and it is easy to combine nucleic acids with

various types of nanomaterials to develop the nanomaterial-assisted biomemory.

17.5.2 Biologic Gate/Bioprocessor

The synergistic effects from the combination of nucleic acids and nanomaterials are also

used in the development of a biologic gate and bioprocessor. Yi’s group developed a bio­

logic gate using AuNP conjugated with cyanine3-tagged aptamer (Cy3-Apt) which can

specifically react with chloramphenicol (CAP) [50]. Due to the fluorescence quenching by

AuNP, Cy3-Apt could not emit the fluorescence signal. However, in the presence of CAP,

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Bioelectronics