Molecular Electronics

Abstract

A molecular electronic device (10) comprises a polynucleotide framework (3), one or more molecular electronic components (4) and one or more electrical contacts (7). The molecular electronic components and the electrical contacts are each connected to the plurality of polynucleotides such that the molecular electronic components and the electrical contacts are positioned relative to the framework and relative to each other. This forms a coupling between the electrical contacts and the molecular electronic components.

Description

[0001] The present invention relates to a molecular electronic device and a method for assembling the molecular electronic device.

[0002] Molecules (e.g., having a defined atomic composition and structural formula) are the smallest objects whose functions can be manipulated. Thus, molecular electronic components offer the greatest potential for miniaturization of circuits. At this scale, quantum phenomena dominate the properties of such devices, and thus molecular electronic components can be used to study the development of components for quantum technologies.

[0003] However, due to their size (often smaller than the smallest metal wires that can possibly be made), molecular electronic components are difficult to manipulate to connect them into circuits, and the yields obtained using conventional engineering methods are very low.

[0004] In one technique, a gap of a few nanometers can be created in a thin wire (called a "break junction") using electric current or mechanical strain. Molecular assemblies can then be deposited on the wire in the hope that one (and only one) molecular assembly will bridge the gap in the wire so that the assembly can then be incorporated into a circuit. However, this technique relies on probability and therefore rarely produces a functioning device. Furthermore, since it is impossible to control the shape of the gap in the wire and the orientation of the molecules relative to the wire with any precision, such "functioning" devices rarely exhibit reproducible properties.

[0005] In another technique, scanning tunneling microscopy can be used to locate and study molecular assemblies deposited on a conductive surface. This process is more reliable and reproducible than inserting molecular assemblies into a broken junction. However, this technique uses bulky experimental equipment, which limits the geometries that can be used for molecular electronic devices, thus ruling out some practical devices.

[0006] It is an object of the present invention to provide improved molecular electronic devices and methods of assembling molecular electronic devices.

[0007] When viewed from a first aspect, the present invention provides a molecular electronic device comprising:

[0008] a framework comprising a plurality of polynucleotides;

[0009] one or more molecular electronic components; and

[0010] one or more electrical contacts;

[0011] wherein the one or more molecular electronic components and the one or more electrical contacts are each connected to one or more polynucleotides of the plurality of polynucleotides such that the one or more molecular electronic components and the one or more electrical contacts are positioned relative to the frame and relative to each other to form a coupling between the one or more electrical contacts and the one or more molecular electronic components.

[0012] When viewed from a second aspect, the present invention provides a method of assembling a molecular electronic device, the method comprising: assembling a framework from a plurality of polynucleotides;

[0013] connecting one or more molecular electronic components to one or more polynucleotides in the plurality of polynucleotides; and connecting one or more electrical contacts to one or more polynucleotides in the plurality of polynucleotides;

[0014] wherein the one or more molecular electronic components and the one or more electrical contacts are each connected to one or more polynucleotides of the plurality of polynucleotides such that the one or more molecular electronic components and the one or more electrical contacts are positioned relative to the frame and relative to each other to form a coupling between the one or more electrical contacts and the one or more molecular electronic components.

[0015] When viewed from a third aspect, the present invention provides a molecular electronic device obtainable by a method according to the second aspect of the present invention as outlined.

[0016] The present invention provides molecular electronic devices and methods for assembling molecular electronic devices. The device comprises a framework, which is assembled from a plurality of polynucleotides (e.g., by hybridization of paired polynucleotides to form a double helix). One or more molecular electronic components and one or more electrical contacts are positioned relative to the polynucleotide framework (e.g., connected to the polynucleotide framework). The one or more electrical contacts are also positioned relative to the one or more molecular electronic components.

[0017] The one or more electrical contacts and the one or more molecular electronic components are positioned relative to the frame and relative to each other by connecting each of the one or more electrical contacts and the one or more molecular electronic components to one or more polynucleotides forming the frame. The one or more electrical contacts and the one or more molecular electronic components are positioned relative to the frame and relative to each other, such as when the frame is assembled, to form a molecular electronic device.

[0018] Similarly, when the device comprises a plurality of molecular electronic components, couplings between (e.g., pairs of) molecular electronic components are preferably formed in the same manner. Thus, in a preferred embodiment, the molecular electronic device comprises a plurality of molecular electronic components, and each of the plurality of molecular electronic components is connected to one or more polynucleotides of the plurality of polynucleotides, such that two or more of the plurality of molecular electronic components are positioned relative to the frame and relative to each other to form couplings between the two or more molecular electronic components.

[0019] Thus, it will be appreciated that by using polynucleotide (e.g., DNA nanotechnology) technology to create a framework and attaching one or more molecular electronic components and one or more electrical contacts to a polynucleotide to position the one or more molecular electronic components and the one or more electrical contacts relative to the framework (and relative to each other), in at least preferred embodiments, due to hybridization between complementary bases of the polynucleotides to form the framework, this helps to allow the one or more molecular electronic components and the one or more electrical contacts to be reliably and accurately positioned relative to each other. This relative positioning of the different components relative to each other allows for the formation of couplings between the one or more molecular electronic components and the one or more electrical contacts and, for example, between multiple (e.g., pairs) of molecular electronic components.

[0020] Using a polynucleotide framework to position one or more electrical contacts and one or more molecular electronic components also helps ensure that only one component is positioned at each desired site on the framework. This helps avoid problems caused by binding of multiple components in, for example, a break junction.

[0021] As part of the formation of a molecular electronic device, coupling between one or more molecular electronic components and one or more electrical contacts (and, for example, multiple (e.g., paired) molecular electronic components) thus provides a connection device (e.g., a single molecular transistor or diode or an integrated circuit including multiple such circuit elements), which can then allow the one or more molecular electronic components to be connected to an external circuit system through one or more external electrical connections to the one or more electrical contacts. Thus, the molecular electronic device can be "connected", for example, as part of an electrical circuit, thereby allowing the molecular electronic components to be used (e.g., their functionality to be controlled). This helps to overcome problems with the prior art in being able to position electrical contacts relative to the molecular electronic components in a reliable and accurate manner, so that the molecular electronic components can be connected into larger circuits.

[0022] The use of polynucleotides (e.g., deoxyribonucleic acid (DNA)) also has the advantage that the properties of such polynucleotides can be exploited. For example, polynucleotides are inherently stable and can therefore be dried while maintaining their structure (e.g., framework structure). This can allow a molecular electronic device to be connected as part of a larger circuit while maintaining the relationship of the components of the molecular electronic device relative to each other. Polynucleotides also have very little inherent conductivity and therefore help provide the necessary structure for the framework in a molecular electronic device without interfering with the electronic function of the device.

[0023] Thus, assembling molecular electronic devices in this manner may be more reliable than conventional techniques, thereby helping to allow for the confident production of functioning devices. Assembling molecular electronic devices in this manner may also be more reproducible than conventional techniques, thereby helping to allow for an increased yield of molecular electronic devices assembled in this manner. Furthermore, due to the ability to synthesize specific polynucleotide sequences, such molecular electronic devices may be able to be constructed into specific designs.

[0024] When the framework is assembled from a plurality of polynucleotides, the framework may comprise any suitable and desired (e.g., one-dimensional, two-dimensional, or three-dimensional) structure. In one embodiment, the framework comprises an array of (e.g., parallel) polynucleotide helices preferably assembled using DNA "origami" or DNA "brick" techniques. The framework may comprise a single double-stranded polynucleotide helical layer, but preferably, the framework comprises a plurality of double-stranded polynucleotide helical layers. The number of layers of the framework may be used to control the spacing of the molecular electronic components from one or more contacts and, for example, the spacing of the contacts from each other when the molecular electronic device comprises more than one contact.

[0025] The framework can include any suitable and desired type of polynucleotide (e.g., synthetic, genomic or modified genomic deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) or nucleic acid analogs such as peptide nucleic acid (PNA), locked nucleic acid (LNA), glycol nucleic acid (GNA), etc.).

[0026] In one embodiment, the multiple polynucleotides include multiple shorter polynucleotides. Such polynucleotides can form most or all of the structure of the formation framework, and help, for example, to connect together the different layers of the formation framework using DNA "brick" technology. Preferably, the shorter polynucleotides (e.g., each) have a total length of less than 100 nucleotides (e.g., less than 50 nucleotides).

[0027] In one embodiment, the plurality of polynucleotides comprises a longer polynucleotide. Preferably, the longer polynucleotide comprises greater than 100 nucleotides, such as greater than 1000 nucleotides.

[0028] In a particularly preferred embodiment, the plurality of polynucleotides comprises both a longer polynucleotide and a plurality of shorter polynucleotides. Preferably, the longer polynucleotide forms a "scaffold" polynucleotide that passes through the framework and is "stapled" together, for example, using shorter polynucleotides, as used in DNA "origami" assembly technology.

[0029] Thus, in a particularly preferred embodiment, the framework comprises a longer polynucleotide and a plurality of shorter polynucleotides, wherein the plurality of shorter polynucleotides are arranged to connect different parts of the longer "scaffold" polynucleotide together, for example to form a double-stranded polynucleotide helical array. Preferably, the method comprises assembling the framework by connecting different parts of the longer polynucleotide together using the plurality of shorter polynucleotides.

[0030] Because of the predictable hybridization of complementary segments of polynucleotides to form a duplex, polynucleotides can be generated (eg, synthesized) that will hybridize such that they assemble into a framework desired structure.

[0031] In one embodiment, the plurality of polynucleotides comprises a natural sequence of polynucleotides, such as for a "scaffold" polynucleotide. In one embodiment, the plurality of polynucleotides comprises a synthetic sequence of nucleotides, such as for a polynucleotide "staple" (and / or a "scaffold" polynucleotide). Thus, in one set of embodiments, the method comprises (e.g., designing and) synthesizing (at least some of) the plurality of polynucleotides.

[0032] The framework can be any suitable and desired size. In one embodiment, the maximum size of the framework is between 50 nm and 200 nm, for example, about 100 nm. It should be understood that double-stranded polynucleotides are rigid in a length of about 50 nm. This helps to build a framework of hundreds of nanometers (e.g., fully defined), which therefore helps to control the geometry and properties of molecular electronic devices, for example, when arranging their components (e.g., one or more molecular electronic components and one or more contacts) relative to each other.

[0033] Preferably, the method comprises bonding the plurality of polynucleotides (e.g., a polynucleotide "scaffold" and a plurality of polynucleotide staples) to assemble the framework. Thus, preferably, the assembled framework comprises substantially a double-stranded polynucleotide helix (e.g., except for single-stranded segments of one or more polynucleotides used to position one or more contacts and one or more molecular electronic components). As will be discussed below, in this same bonding step, or once a plurality of polynucleotides have been bonded to form the framework, one or more contacts and one or more molecular electronic components can be attached to the framework and / or positioned relative to each other (to form one or more couplings therebetween).

[0034] Preferably, for example, when assembling (or having been assembled) the framework, the framework includes one or more (e.g., multiple) polynucleotides having single-stranded segments. As will be discussed, these polynucleotides having single-stranded segments (i.e., not hybridized to other polynucleotides forming the framework) can be used to attach to complementary polynucleotides to connect one or more molecular components and one or more electrical contacts to the framework.

[0035] The assembled frame may comprise any suitable and desired shape. In one embodiment, the frame comprises a substantially cubic shape, for example assembled from a plurality of stacked rectangular layers. Preferably, the frame comprises one or more recesses, the one or more recesses being arranged to respectively position the one or more electrical contacts. For example, when the molecular electronic device comprises two contacts, preferably, the frame comprises recesses formed in opposite sides of the frame for positioning the respective contacts. The shape (e.g., concave) of the one or more recesses (e.g., in addition to the number of layers of the frame) can be used to control the spacing between one or more molecular electronic components and the one or more contacts, and, for example, the spacing between each other at the contacts, when the molecular electronic device comprises more than one contact.

[0036] One or more molecular electronic components connected to the framework can be any one or more suitable and desired molecular electronic components. Preferably, one or more molecular electronic components (e.g., each) have a clearly (e.g., accurately) defined atomic structure, for example, in contrast to less clearly defined molecular structures such as carbon nanotubes (which generally do not have a defined number of carbon atoms). Therefore, preferably, one or more molecular electronic components (e.g., each of the one or more molecular electronic components) are clearly defined (e.g., discrete and preferably single) molecules or groups of molecules. Preferably, one or more molecular electronic components (e.g., each of the one or more molecular electronic components) are not carbon nanotubes.

[0037] (A well-defined molecule (or group of molecules) is one that has a precisely defined formula (atomic composition) and structural formula (showing how the constituent atoms are connected by chemical bonds). For any particular well-defined molecule (or group of molecules), some or all of its stereoisomers (having the same structural formula, but different arrangements of the atoms in space) can be considered functionally equivalent. Thus, a mixture of stereoisomers can be considered the same particular well-defined molecule (or group of molecules).)

[0038] In one embodiment, the molecular weight of the one or more molecular electronic components is between 100 Daltons (Da) and 10,000 Da, such as between 500 Da and 5,000 Da, such as between 1,000 Da and 3,000 Da, such as about 2,600 Da.

[0039] In one embodiment, the one or more molecular electronic components comprise a magnetic heterometallic ring. In one embodiment, the one or more molecular electronic components comprise an antiferromagnetic ring. Preferably, the ring comprises a Cr7M ring, wherein M comprises a metal, such as Ni (e.g., Ni II ), Co (e.g., Co II ), Fe (e.g., Fe II or Fe III ).

[0040] In one embodiment, the one or more molecular electronic components comprise a rotaxane. Preferably, the rotaxane comprises a (macrocyclic) ring having an axis extending through it. Preferably, the axis (e.g. having a dumbbell shape) is held within the ring. Preferably, the (e.g. hybrid) rotaxane comprises an inorganic ring and an organic axis. Preferably, the inorganic ring comprises a magnetic heterometallic ring and / or an antiferromagnetic ring, such as a Cr7M ring, wherein M comprises a (e.g. transition) metal, such as Ni (e.g. Ni II ), Co (e.g., Co II ), Fe (e.g., Fe II or Fe III ).

[0041] In these above-described embodiments, preferably, the one or more molecular electronic components are used as (and thus preferably comprise) molecular quantum dots.

[0042] Such molecular electronic components, such as molecular nanomagnets (eg, antiferromagnetically coupled clusters based on transition metals) are useful for providing, for example, atomically well-defined molecules (eg, groups of molecules) with internal magnetic degrees of freedom, such as molecular quantum dots.

[0043] Preferably, the method comprises selecting specific (e.g., well-defined) molecules or groups of molecules for use as one or more molecular components. In a preferred embodiment, the method comprises (e.g., designing and) synthesizing (e.g., specific (e.g., well-defined) molecules or groups of molecules for use as) one or more molecular components. As already explained, due to the (e.g., well-defined) properties of the molecular electronic components (e.g., such that copies of the molecular electronic components are (substantially) identical), the (e.g., well-defined) molecular electronic components, when connected to one or more polynucleotides of a plurality of polynucleotides, have the ability to align or self-assemble (and thus, for example, accurately position) themselves relative to the framework of the molecular electronic device in a way that is not always possible with less well-defined structures (such as carbon nanotubes).

[0044] The one or more molecular electronic components may include any suitable and desired type of electronic component. For example, the one or more molecular electronic components may include one or more of the following: a diode, a (e.g., field effect) transistor, a (e.g., molecular spin) qubit, or a (e.g., magnetic) molecular quantum dot, etc. In one embodiment, the one or more molecular electronic components include a single molecule electronic component. As will be discussed below, preferably, the one or more molecular electronic components are configured so that they (e.g., each) can be connected to the framework, for example, via one or more covalent bonds of a polynucleotide hybridized to other components of the framework.

[0045] The one or more molecular electronic components may be connected to one or more polynucleotides of the plurality of polynucleotides forming the framework in any suitable and desired manner. In one set of embodiments, the molecular electronic device comprises one or more ("connection") polynucleotides attached to the one or more molecular electronic components (e.g., each of the one or more molecular electronic components) and arranged to connect the one or more molecular electronic components to one or more polynucleotides of the plurality of polynucleotides forming the framework so as to position the one or more molecular electronic components relative to the framework (and relative to one or more electrical contacts).

[0046] Thus, preferably, the method comprises attaching one or more polynucleotides to the one or more molecular electronic components (e.g., each of the one or more molecular electronic components), and using the one or more polynucleotides attached to the one or more molecular electronic components to position the one or more molecular electronic components relative to the framework, e.g., by hybridizing the one or more polynucleotides attached to the one or more molecular electronic components with one or more polynucleotides of the plurality of polynucleotides forming the framework.

[0047] Preferably, the one or more polynucleotides attached to the one or more molecular electronic components are connected to one or more polynucleotides of the plurality of polynucleotides forming the framework simultaneously and in the same assembly process as the assembly process used to assemble the framework, for example by gluing or otherwise combining the plurality of polynucleotides forming the framework with the polynucleotides attached to the one or more molecular electronic components.

[0048] In these embodiments, preferably, the one or more molecular electronic components are connected to the framework by hybridization of the one or more polynucleotides attached to the one or more molecular electronic components to a single stranded segment of the one or more polynucleotides forming part of the framework. Thus, preferably, the one or more polynucleotides attached to the one or more molecular electronic components do not themselves form part of the framework, but are attached to the framework.

[0049] In one embodiment, the one or more molecular electronic components (e.g., each) are directly attached to one or more polynucleotides in the plurality of polynucleotides forming the framework, e.g., not via one or more additional connecting polynucleotides. Therefore, preferably, the method comprises attaching the one or more molecular electronic components (e.g., each of the one or more molecular electronic components) to one or more polynucleotides in the plurality of polynucleotides forming the framework. In embodiments where the framework is assembled according to the "DNA origami" technique, the one or more molecular electronic components may be directly attached to (e.g., longer) "scaffold" polynucleotides and / or one or more polynucleotide "staples" in (e.g., shorter) polynucleotide "staples" forming the framework.

[0050] One or more molecular electronic components can be attached to one or more polynucleotides for positioning one or more molecular electronic components relative to the framework in any suitable and desired manner. In one embodiment, the one or more molecular electronic components are attached to the corresponding ends of the one or more polynucleotides in the multiple polynucleotides forming the framework or one or more connecting polynucleotides, for example as terminal modifications. Thus, for example, one or more molecular electronic components to which one or more polynucleotides are attached are prepared in this manner, for example, for then being connected to or forming a framework.

[0051] In another embodiment, the one or more molecular electronic components are attached as internal modifications to one or more polynucleotides or one or more connecting polynucleotides of the plurality of polynucleotides forming the framework (i.e., such that the modified polynucleotides are contiguous across the molecular electronic component, with ends of the polynucleotides protruding from either side of the molecular electronic component and the ends are free (i.e., single-stranded), for example to hybridize with complementary polynucleotides).

[0052] In order to attach the one or more molecular electronic components to one or more polynucleotides or one or more connecting polynucleotides in the multiple polynucleotides forming the framework, the one or more polynucleotides can first be combined with one or more complementary polynucleotides as part of a double helix. This can help locate the molecular electronic component and thus attach it to the one or more polynucleotides (e.g., through one or more corresponding covalent bonds). Preferably, once the molecular electronic component has been attached to the one or more polynucleotides, the complementary polynucleotides are removed, thereby attaching the molecular electronic component to the one or more polynucleotides or one or more connecting polynucleotides forming the framework.

[0053] In one embodiment, the one or more molecular electronic components (eg, each) are inserted, eg, as a backbone link, in one or more polynucleotides of the plurality of polynucleotides forming the framework or in the one or more connecting polynucleotides.

[0054] In one set of embodiments, the plurality of polynucleotides, the one or more molecular electronic components (and where appropriate, the one or more connecting polynucleotides) forming the framework may be arranged so that the framework can only be (e.g., correctly) assembled when the one or more molecular electronic components are present. Thus, when the one or more molecular electronic components and the polynucleotides to which they are attached are not present, the plurality of polynucleotides may be prevented from (e.g., correctly) assembling into the framework. This may facilitate tighter control over the assembly of the framework and / or the positioning of the one or more molecular electronic components.

[0055] One or more molecular electronic components can be (e.g., each) attached to one or more polynucleotides in the plurality of polynucleotides or one or more connecting polynucleotides (for connection to the framework) in any suitable and desired manner. In one embodiment, the one or more molecular electronic components are (e.g., each) attached to the one or more polynucleotides in the plurality of polynucleotides or the one or more connecting polynucleotides forming the framework via one or more corresponding covalent bonds.

[0056] Preferably, the one or more polynucleotides (e.g., each of the one or more polynucleotides) of the plurality of polynucleotides forming the framework or the one or more linker polynucleotides to which the one or more molecular electronic components are attached comprise peripheral functional groups (e.g., thiol, carboxyl, amine, alkyne, azide or acrylate) to form one or more covalent bonds with the one or more molecular electronic components. Thus, preferably, the method comprises functionalizing one, more or all of the one or more molecular electronic components and the one or more polynucleotides of the plurality of polynucleotides forming the framework and / or the one or more linker polynucleotides, as appropriate, to attach to each other.

[0057] Although, in some embodiments, the one or more molecular electronic components can be (e.g., each) connected to the framework using or through only a single framework polynucleotide or connecting polynucleotide, it should be understood that in some embodiments, connecting the one or more molecular electronic components to the framework (e.g., each) using two or three (or more) polynucleotides or connecting polynucleotides (e.g., each molecular electronic component) forming the framework can help to more accurately position (and, for example, orient) the one or more molecular electronic components relative to the framework and / or help to strengthen or stiffen one or more connections between the one or more molecular electronic components and the framework.

[0058] It should be understood that when multiple polynucleotides or connecting polynucleotides forming a framework are attached to one or more molecular electronic components (e.g., each of the one or more molecular electronic components) to connect and position the one or more molecular electronic components to the framework, the multiple polynucleotides or connecting polynucleotides can be attached in a variety of different ways (e.g., using one or more of the techniques outlined herein).

[0059] One or more molecular electronic components can be (e.g., each) positioned in any one or more suitable and desired positions relative to the framework, e.g., independently of how the one or more molecular electronic components are connected to the polynucleotides forming the framework. In one embodiment, the one or more molecular electronic components are positioned substantially at the center of the framework. When the framework includes a depression (e.g., for positioning the one or more contacts), preferably, the one or more molecular electronic components are positioned substantially at the center (e.g., bottom) of the depression.

[0060] The one or more electrical contacts of the molecular electronic device that are positioned relative to the frame and relative to the one or more molecular electronic components and form a coupling to the one or more molecular electronic components can be any suitable and desired type of electrical contacts. Preferably, the one or more contacts (once positioned on the frame) are each arranged to be connected to a contact or docking site. This is to allow an electrical connection to be established with an external circuit component (e.g., via a contact pad to a component on a (e.g., photolithographic) patterned surface) or to a contact in another molecular electronic device. Therefore, preferably, the method includes connecting each of the one or more contacts to a contact pad (e.g., of an external circuit) or a contact of another molecular electronic device.

[0061] In one embodiment, the one or more electrical contacts are made externally, i.e., the one or more electrical contacts are made before being connected to one or more polynucleotides in the plurality of polynucleotides to couple to the one or more molecular electronic components. Thus, preferably, the method comprises making the one or more electrical contacts (e.g., of a size as outlined below), and then connecting the one or more made electrical contacts to one or more polynucleotides in the plurality of polynucleotides. Preferably, the one or more electrical contacts are each made as a single particle, e.g., to contrast with the use of a plurality of seed (e.g., nano) particles to nucleate the growth of the contacts in situ.

[0062] In one embodiment, the one or more electrical contacts include one or more inorganic contacts (i.e., one or more contacts formed of an inorganic material), such as one or more metal contacts. In one embodiment, the one or more electrical contacts include one or more gold contacts. In one embodiment, the one or more electrical contacts include one or more conductive nanoparticles.

[0063] In one embodiment, the one or more electrical contacts include one or more conductive molecular components, such as one or more conductive oligomers. Preferably, these one or more conductive molecular components include functional groups to contact with a contact pad (e.g., of an external circuit) or a contact of another molecular electronic device.

[0064] Preferably, the maximum dimension (e.g., diameter) of the one or more electrical contacts (each) is between 20nm and 100nm, such as between 40nm and 80nm, such as between 50nm and 70nm, such as about 60nm. Preferably, the minimum dimension of the one or more electrical contacts (each) is greater than 10nm, such as greater than 30nm, such as greater than 50nm. Therefore, preferably, the one or more electrical contacts include, for example, one or more gold nanoparticles having a diameter of about 60nm. Providing one or more electrical contacts of this size facilitates its connection to one or more external electrical connections, such as to connect to a contact pad on a (e.g., photolithographic) patterned surface or another contact in another molecular electronic device, for example using photolithographic techniques.

[0065] Preferably, the one or more electrical contacts are (each) larger than the one or more molecular electronic components of the device. This is because one or more external electrical connections that may be required to connect the one or more electrical contacts are typically explicitly formed using manufacturing techniques such as photolithography. This is in contrast to the coupling between the one or more electrical contacts and the one or more molecular electronic components, which is preferably automatically formed due to the connection between the multiple polynucleotides and each of the one or more electrical contacts and the one or more molecular electronic components.

[0066] The one or more electrical contacts may be connected to one or more of the plurality of polynucleotides forming the framework in any suitable and desired manner. In one set of embodiments, the molecular electronic device comprises one or more connecting polynucleotides attached to the one or more electrical contacts (e.g., each of the one or more electrical contacts) and arranged to connect the one or more electrical contacts to one or more of the plurality of polynucleotides forming the framework so that the one or more electrical contacts are positioned relative to the framework (and relative to one or more molecular electronic components).

[0067] Thus, preferably, the method comprises attaching one or more connecting polynucleotides to the one or more electrical contacts (e.g., each of the one or more electrical contacts), and connecting the one or more electrical contacts to the one or more polynucleotides in the plurality of polynucleotides forming the framework, so as to position the one or more electrical contacts relative to the framework using the one or more connecting polynucleotides attached to the one or more electrical contacts. In one embodiment, for example, as with the external manufacture of the one or more electrical contacts, preferably, before the one or more electrical contacts are connected to the one or more polynucleotides in the plurality of polynucleotides, the one or more connecting polynucleotides are externally attached to the one or more electrical contacts. This is in contrast to the use of chemical groups, which are used to attract seed particles or nucleate them for further aggregation or deposition to form contacts.

[0068] In these embodiments, preferably, the one or more electrical contacts are connected to the framework by hybridization of the one or more connecting polynucleotides attached to the one or more electrical contacts to a single-stranded segment (e.g., a sticky end) of one or more polynucleotides forming part of the framework. Thus, preferably, the one or more connecting polynucleotides attached to the one or more electrical contacts do not themselves form part of the framework, but are attached to the framework.

[0069] In one embodiment, the one or more electrical contacts (e.g., each) are directly attached to one or more polynucleotides in the plurality of polynucleotides forming the framework, e.g., not via one or more additional connecting polynucleotides. Therefore, preferably, the method comprises attaching the one or more electrical contacts (e.g., each of the one or more electrical contacts) to one or more polynucleotides in the plurality of polynucleotides forming the framework. In embodiments where the framework is assembled according to the "DNA origami" technique, the one or more electrical contacts may be directly attached to (e.g., longer) "scaffold" polynucleotides and / or one or more polynucleotide "staples" in (e.g., shorter) polynucleotide "staples" forming the framework.

[0070] For example, the framework may include one or more docking sites for the one or more electrical contacts, respectively. The one or more electrical contacts may be positioned at the one or more docking sites by non-specific attractive interactions (e.g., van der Waals forces). Therefore, preferably, one or more polynucleotides in the plurality of polynucleotides forming the framework are prepared with non-specific attractive interactions to form one or more docking sites.

[0071] In the embodiments outlined above, for example, wherein the one or more electrical contacts are attached to one or more polynucleotides or one or more connecting polynucleotides of the plurality of polynucleotides forming the framework, the one or more electrical contacts may be attached to these polynucleotides in any suitable and desired manner (e.g., via one or more docking sites). The one or more electrical contacts may be attached to the one or more polynucleotides or one or more connecting polynucleotides before or after these polynucleotides are assembled to form the framework or attached to the framework, or the one or more electrical contacts may be attached during assembly of the polynucleotide framework.

[0072] In one embodiment, the one or more electrical contacts are attached to the corresponding ends of the one or more polynucleotides in the plurality of polynucleotides forming the framework or to one or more connecting polynucleotides. Thus, for example, one or more electrical contacts to which one or more polynucleotides are attached are prepared in this manner, for example, for then being connected to or forming a framework.

[0073] Although, in some embodiments, the one or more electrical contacts may be connected to the framework (e.g., each) using or by only a single polynucleotide or connecting polynucleotide, it should be understood that in some embodiments, connecting the one or more electrical contacts to the framework (e.g., each) using two or three (or more) polynucleotides or connecting polynucleotides (e.g., each electrical contact) forming the framework can help to more accurately position the one or more electrical contacts relative to the framework and / or help to strengthen or stiffen the connection of the one or more electrical contacts to the framework. This can help to provide a reliable electrical connection between the one or more electrical contacts and the one or more molecular electronic components.

[0074] In a preferred embodiment, the molecular electronic device comprises 1 to 10,000 connecting polynucleotides (e.g., about 1,000 connecting polynucleotides), the connecting polynucleotides being attached to the one or more electrical contacts (e.g., each of the one or more electrical contacts) to connect the one or more electrical contacts to one or more polynucleotides of the plurality of polynucleotides forming the framework to form a coupling between the one or more electrical contacts and the one or more molecular electronic components (and, for example, between a plurality of (e.g., pairs of) molecular electronic components). Preferably, the plurality of polynucleotides forming the framework comprises 1 to 100 (e.g., about 10) polynucleotides (e.g., each electrical contact), each polynucleotide comprising a single-stranded segment (e.g., a sticky end) for hybridizing with a complementary polynucleotide attached to the one or more electrical contacts to connect the one or more electrical contacts to the plurality of polynucleotides forming the framework.

[0075] In one embodiment, the framework includes two or more positions for positioning two or more electrical contacts, respectively, wherein the one or more polynucleotides (e.g., in their single-stranded segments) forming the framework at each of the two or more positions have different base sequences (e.g., base sequence combinations). This can help guide electrical contacts of different sizes to different positions on the framework. However, it should be understood that multiple electrical contacts can be connected to the polynucleotides forming the framework using the same base sequence.

[0076] It should be understood that when multiple polynucleotides or connecting polynucleotides are attached to one or more molecular electronic components (e.g., each of the one or more molecular electronic components) to connect and position the one or more molecular electronic components to the framework, the multiple polynucleotides or connecting polynucleotides can be attached in a variety of different ways (e.g., using one or more of the techniques outlined herein).

[0077] One or more electrical contacts can be (e.g., each) attached to one or more polynucleotides in the plurality of polynucleotides forming the framework or one or more connecting polynucleotides (for connecting to the framework) in any suitable and desired manner. In an embodiment, the one or more electrical contacts are (e.g., each) attached to the one or more polynucleotides in the plurality of polynucleotides forming the framework or the one or more connecting polynucleotides via corresponding covalent bonds.

[0078] Preferably, the one or more polynucleotides (e.g., each of the one or more polynucleotides) of the plurality of polynucleotides forming the framework or the one or more connecting polynucleotides to which the one or more molecular electronic components are attached include peripheral functional groups (e.g., thiol, carboxyl, amine, alkyne, azide or acrylate) to form one or more covalent bonds with the one or more corresponding electrical contacts. In one embodiment, a thiol or heterocyclic carbene functional group can be used to form a bond directly with a gold surface. Therefore, preferably, the method comprises functionalizing one, more or all of the one or more electrical contacts and / or one or more polynucleotides of the plurality of polynucleotides forming the framework and / or one or more connecting polynucleotides as appropriate to attach to each other.

[0079] When the one or more electrical contacts are positioned relative to the frame, this forms a coupling (or couplings) between the one or more electrical contacts (e.g., each electrical contact) and the one or more molecular electronic components. The one or more couplings allow the molecular electronic device to be incorporated into a larger circuit, such that the operation of the one or more molecular electronic components can be controlled, for example, by applying an electrical potential through the one or more electrical contacts.

[0080] The coupling between one or more electrical contacts (e.g., each of the one or more electrical contacts) and one or more molecular electronic components and (and, for example, between multiple (e.g., paired) molecular electronic components) can be any suitable and desired coupling, for example, which allows control of the operation of one or more molecular electronic components. In one embodiment, the coupling includes a (e.g., high) conductive coupling (e.g., a high conductive coupling that is electron transparent). In another embodiment, the coupling includes a (e.g., high) resistive coupling (e.g., a high resistive coupling that is electron opaque). It should be understood that when the molecular electronic device includes multiple couplings between one or more molecular electronic components and multiple electrical contacts (and, for example, between multiple (e.g., paired) molecular electronic components), the multiple couplings can include any suitable and desired mixture of conductive couplings and non-conductive couplings.

[0081] The type of coupling can depend on the type of molecular electronic component and how it is desired to be controlled. For example, when the molecular electronic component comprises a field effect transistor, the coupling to the source terminal and the drain terminal each comprises a conductive coupling, and the coupling to the gate terminal comprises a non-conductive coupling (but for example, the gate is close enough to the channel of the transistor to affect conduction between the source terminal and the drain terminal).

[0082] One or more couplings may be formed in any suitable and desired manner. In one embodiment, the one or more couplings may each be formed by controlling one or more distances between the position of the one or more electrical contacts on the frame and the position of the one or more molecular electronic components (and, for example, between multiple (e.g., paired) molecular electronic components), for example, due to the design (e.g., shape and / or size) of the frame. For example, the number of layers of the frame and / or the shape and / or size of the recesses on the frame in which the one or more electrical contacts are positioned may be selected to control one or more distances between the one or more electrical contacts and the one or more molecular electronic components.

[0083] Such (e.g., electrostatic) coupling due to distance may be a conductive coupling (e.g., a tunneling connection) or a non-conductive coupling. Thus, in one embodiment, the coupling allows electrons to tunnel across the coupling. The conductive or non-conductive nature of one or more couplings may be controlled by the distance between one or more molecular electronic components and one or more electrical contacts (or between multiple (e.g., paired) molecular electronic components), the one or more molecular electronic components and the one or more electrical contacts being coupled together by the coupling, which in turn is preferably set by the relative position of the one or more molecular electronic components and the one or more electrical contacts on the frame.

[0084] In one embodiment, the coupling is formed by controlling the distance between the one or more corresponding molecular electronic components and the one or more electrical contacts (or between multiple (e.g., pairs of) molecular electronic components), and does not include chemical bonds therebetween, for example. Preferably, such coupling is non-conductive (high impedance).

[0085] In one embodiment, the coupling is formed by forming covalent or other chemical bonds between the one or more molecular electronic components and the one or more electrical contacts.

[0086] In one embodiment, when the one or more molecular electronic components and the one or more electrical contacts are positioned on the frame and relative to each other, some or all of the one or more molecular electronic components and the one or more electrical contacts are functionalized to form the one or more couplings. Therefore, preferably, the method includes functionalizing some or all of the one or more molecular electronic components and the one or more electrical contacts so that the one or more couplings are formed when the one or more molecular electronic components and / or the one or more electrical contacts are positioned on the frame and relative to each other. Providing chemical functional groups on the one or more molecular electronic components and / or the one or more electrical contacts helps to allow a bond to be formed between the one or more molecular electronic components and (e.g., corresponding) one or more electrical contacts (or between multiple (e.g., paired) molecular electronic components), such that the characteristics of the bond determine the (e.g., conductive or non-conductive) nature of the coupling.

[0087] It should be understood that in some embodiments, the formation of the one or more couplings is controlled by the distance between the one or more molecular electronic components and the (e.g., corresponding) one or more electrical contacts (or between multiple (e.g., paired) molecular electronic components) and the combination of chemical functional groups of the one or more molecular electronic components and / or the (e.g., corresponding) one or more electrical contacts. For example, one or more relative positions of one or more molecular electronic components and (e.g., corresponding) one or more electrical contacts (or (e.g., paired) molecular electronic components) on the frame can be selected so that the distance between them determines the type of one or more chemical bonds formed to provide one or more couplings. This helps to precisely control the relative position and spacing of one or more molecular electronic components and (e.g., corresponding) one or more electrical contacts (or (e.g., paired) molecular electronic components) while providing the desired (e.g., conductive or non-conductive) coupling therebetween.

[0088] When the coupling is formed by chemical functional groups on one or more molecular electronic components and / or (e.g., corresponding) one or more electrical contacts (or (e.g., paired) molecular electronic components), the coupling can be a conductive coupling or a non-conductive coupling. The conductive or non-conductive nature of the one or more couplings can be controlled by the chemical structure of the bonds between the one or more molecular electronic components and (e.g., corresponding) one or more electrical contacts (or between multiple (e.g., paired) molecular electronic components), wherein the one or more molecular electronic components and the one or more electrical contacts are coupled together by the (e.g., corresponding) chemical structure of the coupling and / or the proximal portions (e.g., surfaces) of the one or more molecular electronic components and / or the one or more electrical contacts (or one or more proximal portions of one or more (e.g., paired) molecular electronic components). For example, the chemical bonds can be conductive or non-conductive, and / or the proximal portions (e.g., surface or proximal chemical bonds) of one or more molecular electronic components and / or (e.g., corresponding) one or more electrical contacts (or one or more proximal portions of one or more (e.g., paired) molecular electronic components) can be conductive or non-conductive (insulating), as appropriate, to form the desired coupling.

[0089] In one set of embodiments, the molecular electronic device includes one or more conductive oligomers or other substantially conductive molecules, which are arranged between the one or more molecular electronic components and the one or more electrical contacts (e.g., each of the one or more electrical contacts) (or between multiple (e.g., pairs of) molecular electronic components) to form part of the coupling between the one or more molecular electronic components and the one or more electrical contacts (or between multiple (e.g., pairs of) molecular electronic components). Therefore, preferably, the method includes attaching one or more conductive oligomers or other substantially conductive molecules between the one or more molecular electronic components and the one or more electrical contacts (e.g., each of the one or more electrical contacts) (or between multiple (e.g., pairs of) molecular electronic components).

[0090] Preferably, the one or more conductive oligomers or other substantially conductive molecules are attached to the one or more molecular electronic components and the one or more electrical contacts (e.g., at each of their respective ends), e.g., by covalent bonds. The one or more conductive oligomers or other substantially conductive molecules may be attached to the one or more molecular electronic components and / or the one or more electrical contacts before or after the one or more molecular electronic components and / or the one or more electrical contacts are connected to the framework, or the one or more conductive oligomers or other substantially conductive molecules may be attached during one of the same assembly steps outlined above, e.g., to assemble the polynucleotide framework.

[0091] Any of the techniques outlined above for positioning molecular electronic components or electrical contacts relative to a polynucleotide framework and relative to each other may be used to position a conductive oligomer or other substantially conductive molecule relative to the framework and relative to other components of the device by one or more polynucleotides attached to (e.g., each) a conductive oligomer or other substantially conductive molecule. In one embodiment, the coupling between the one or more conductive oligomers or other substantially conductive molecules and the one or more molecular electronic components and / or the one or more electrical contacts (e.g., forming part of the coupling between the one or more molecular electronic components and the one or more electrical contacts) is formed by controlling the distance between the one or more conductive oligomers or other substantially conductive molecules and the one or more molecular electronic components and / or the one or more electrical contacts.

[0092] Thus, in a manner similar to that outlined above for the one or more molecular electronic components and / or the one or electrical contacts, in one embodiment, the one or more conductive oligomers or other substantially conductive molecules are functionalized to attach them to the corresponding one or more molecular electronic components and one or more electrical contacts to form the one or more couplings. Thus, preferably, the method comprises functionalizing one, more or all of the one or more molecular electronic components, one or more electrical contacts and one or more conductive oligomers or other substantially conductive molecules, as appropriate, to attach them to each other. Again, preferably, the chemical properties of the one or more conductive oligomers or other substantially conductive molecules, their functional groups and / or their attachment to the corresponding one or more molecular electronic components and one or more electrical contacts are configured to determine the (e.g., conductive or non-conductive) properties of the one or more couplings.

[0093] Preferably, when the various parts of the device are functionalized to attach themselves to each other, one or both of the one or more molecular electronic components and the one or more electrical contacts include one or more functional groups (e.g., thiol, carboxyl, amine, alkyne, azide or acrylate). As outlined above, chemical functional groups help to allow (e.g., covalent) bonds to form between the various parts of the device that are attached to each other. For example, a thiol or heterocyclic carbene functional group on a molecular electronic component can react with the (e.g., gold) surface of an electrical contact to provide a (e.g., -S-Au) bond.

[0094] The molecular electronic device can be assembled in any suitable and desired manner. In one embodiment, one or more (e.g., all) of the assembly steps (e.g., assembling the framework from the plurality of polynucleotides; connecting the one or more molecular electronic components to the framework; connecting the one or more electrical contacts to the framework; coupling the one or more molecular electronic components to each other and to the one or more electrical contacts) are performed, for example, in an aqueous solution (e.g., a buffer solution providing a suitable pH) during the same or separate bonding process. In another embodiment, one or more of these assembly steps are performed in an alternative solvent (e.g., glycerol and choline chloride) or a mixture of solvents (e.g., dimethylformamide and water).

[0095] Preferably, multiple molecular electronic devices are assembled simultaneously, for example, by combining necessary components together and, for example, bonding the frame and other components. It should be appreciated that the chemistry of assembly of molecular electronic devices facilitates mass production of such devices in an efficient and reproducible manner while maintaining the accuracy of assembling each individual device, such that many (e.g., trillions) of substantially identical molecular electronic devices can be manufactured simultaneously.

[0096] When viewed from a further aspect, the invention provides a method of assembling a plurality of (e.g., substantially identical) molecular electronic devices, the method comprising:

[0097] Assembling multiple frames, each frame being assembled from multiple polynucleotides;

[0098] For each frame in the plurality of frames, the method comprises:

[0099] attaching one or more molecular electronic components to one or more polynucleotides of the plurality of polynucleotides; and

[0100] connecting one or more electrical contacts to one or more polynucleotides of the plurality of polynucleotides;

[0101] wherein the one or more molecular electronic components and the one or more electrical contacts are each connected to one or more polynucleotides of the plurality of polynucleotides such that the one or more molecular electronic components and the one or more electrical contacts are positioned relative to the frame and relative to each other to form a coupling between the one or more electrical contacts and the one or more molecular electronic components.

[0102] When viewed from a further aspect, the present invention provides a variety of molecular electronic devices obtainable by the methods outlined in accordance with the above aspects of the present invention.

[0103] It should be understood that the above aspects may (and preferably) include any one or more (e.g., all) of the optional and preferred features outlined herein, as appropriate. Specifically, the features outlined herein relating to a single molecular electronic device and its assembly are preferably also applicable to multiple molecular electronic devices (e.g., each of the multiple molecular electronic devices).

[0104] Due to the precise assembly of the polynucleotides relative to each other, thus forming a framework and positioning the one or more molecular electronic components and the one or more electrical contacts relative to each other and relative to the framework, the process of the present invention can be highly reproducible and produce devices according to the present invention in high yield. In one embodiment, the method produces greater than 10 in a single reaction. 9 For example, more than 10 10 For example, more than 10 11 For example, about 10 12 In one embodiment, the yield of the method (the percentage of the group of components that have been (e.g. correctly) assembled into (e.g. substantially identical) molecular electronic devices) is greater than 10%, such as greater than 20%, such as greater than 30%, such as greater than 40%, such as greater than 50%, such as greater than 60%, such as greater than 70%, such as greater than 80%, such as greater than 90%.

[0105] Thus, when a plurality of molecular electronic devices are assembled together, preferably, at least 50%, at least 60%, at least 70%, at least 80%, for example, at least 90% of a plurality of molecular electronic components in one or more molecular electronic components are substantially identical. Preferably, at least 50%, at least 60%, at least 70%, at least 80%, for example, at least 90% of a plurality of electrical contacts in one or more electrical contacts are substantially identical. Preferably, at least 50%, at least 60%, at least 70%, at least 80%, for example, at least 90% of a plurality of frames are substantially identical.

[0106] It will be appreciated that the ability of molecular electronic devices to align or self-assemble themselves (e.g., due to the well-defined (and, e.g., substantially identical) properties of the molecular electronic components) helps provide a process that is reproducible with high yields. Such molecular systems have advantages over the heterogeneous nature of carbon nanotubes, metal nanodots, and semiconductor quantum dots, whose assembly would likely result in lower yields.

[0107] Once the molecular electronic device has been assembled, the molecular electronic device (e.g., a plurality of molecular electronic components and electrical contacts assembled together) is preferably deposited on a (e.g., insulating) substrate. Thus, preferably, the molecular electronic device comprises a substrate on which the framework (and one or more molecular electronic components, one or more electrical contacts, and any other associated components (e.g., one or more couplings)) is deposited.

[0108] The substrate may be any suitable and desired substrate. In one embodiment, the substrate comprises a silicon substrate (e.g., silicon dioxide thereon). It should be understood that the properties of the molecular electronic device (particularly, the framework) may help allow it to be arranged on such a substrate.

[0109] Once the molecular electronic device has been deposited on the substrate, for example such that the relative positions of one or more molecular electronic components, one or more electrical contacts, and any other associated components (e.g., one or more couplings) have been fixed, all or part of the frame can be dissolved, thereby attaching the remainder of the molecular electronic device to the substrate. Thus, in one embodiment, the method includes dissolving at least a portion of the frame.

[0110] The polynucleotides forming the framework can be removed or dissolved using enzymatic or chemical degradation. Since RNA is less chemically stable than DNA, using RNA as the polynucleotide forming the framework may be particularly suitable for this purpose.

[0111] In one embodiment, the substrate comprises a pre-patterned substrate. This may help locate and orient one or more molecular electronic devices deposited on the substrate and / or make external electrical connections to one or more contacts of the molecular electronic device. Preferably, the pre-patterned substrate comprises one or more contact pads, for example for connecting external wires to the contact pads and / or for connecting to the one or more contacts of the molecular electronic device.

[0112] Preferably, the electrical connection is made, for example, from one or more contact pads on the substrate to the one or more electrical contacts (i.e., external to the molecular electronic device). Thus, preferably, the method comprises forming one or more electrical connections from the one or more electrical contacts, for example to one or more contact pads on a (e.g., photolithographically) patterned surface or to one or more other contacts in one or more molecular electronic devices. In one embodiment, photolithography, such as electron beam induced deposition (e.g., for platinum) or patterned deposition (e.g., for gold) with the aid of resist processing, is used to form the electrical connection to the one or more electrical contacts (e.g., wires on the substrate).

[0113] Thus, preferably, the molecular electronic device comprises one or more electrical connections to one or more electrical contacts, respectively. Preferably, the one or more electrical connections are formed to (e.g. external) electronic circuitry or one or more other molecular electronic devices. Thus, a plurality of molecular electronic devices may be connected together (e.g. directly) via one or more electrical connections formed between their respective contacts.

[0114] In another embodiment, for example, if the device is positioned accurately enough, direct contact is made between the one or more electrical contacts and one or more corresponding contact pads on the substrate. Thus, multiple molecular electronic devices can be connected together by direct connections (e.g., directly) between corresponding contacts of the molecular electronic devices, for example due to their relative positioning (e.g., on a substrate) or due to layered assembly of multiple devices by hybridization of polynucleotides and without the need to form additional electrical connections. This can avoid the need to form any intermediate electrical connections.

[0115] It should be understood that the molecular electronic device can include a plurality of molecular electronic components, each of which is connected to one or more polynucleotides of a plurality of polynucleotides forming a framework. In these embodiments, one or more (or all) of the techniques outlined above can be used to connect the various components of the molecular electronic device together, such that the molecular electronic component and one or more electrical contacts and one or more connecting oligomers and one or more couplings (where necessary) are connected to the framework and positioned relative to the framework so that couplings between the molecular electronic component and the one or more electrical contacts are formed.

[0116] Thus, in some embodiments, multiple molecular electronic components can be connected to the frame and coupled to one or more corresponding electrical contacts. However, preferably, the multiple molecular electronic components are coupled to each other and to one or more electrical contacts. This allows multiple molecular electronic components to be connected as part of a more complex circuit, rather than just having a single molecular electronic component positioned on each frame.

[0117] As outlined in any of the embodiments described herein, one or more (e.g., all) of the connections, couplings, attachments, etc., for a molecular electronic device comprising a plurality of molecular components can be provided. For example, the methods described above for forming one or more couplings between a molecular electronic component and a corresponding electrical contact can be equally applicable to forming one or more (e.g., conductive or non-conductive) couplings between two or more molecular electronic components positioned relative to each other on a frame in the same manner as the molecular electronic component and the corresponding electrical contact. In this manner, a molecular integrated circuit having inputs and outputs coupled to corresponding electrical contacts can be formed.

[0118] It will therefore be appreciated that multiple molecular electronic devices according to the present invention may be assembled together to form larger composite devices, for example in a hierarchical assembly scheme using molecular self-assembly techniques, where (e.g., internal) connections are formed between contact points on the component molecular electronic devices.

[0119] Various embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:

[0120] Figure 1a , 1b , 1c and 1d schematically illustrate components and structures of a molecular electronic device assembled according to an embodiment of the present invention;

[0121] Figure 2 A view showing a molecular electronic device deposited on a substrate;

[0122] Figure 3a and 3b schematically illustrates a molecular electronic device according to two embodiments of the present invention; and

[0123] Figure 4a and 4b Two embodiments of molecular electronic devices are schematically shown.

[0124] Molecular electronic components can provide the maximum limit for the miniaturization of circuits. At this scale, quantum phenomena dominate the properties of such devices, and thus molecular electronic components can be used to study the development of components for quantum technologies. Embodiments of the present invention will now be discussed, which outline molecular electronic devices and methods of assembling molecular electronic devices.

[0125] Figure 1a , 1b , 1c and 1d schematically illustrate a molecular electronic device 10 assembled according to an embodiment of the present invention. Figure 1a Schematically shown is a single-stranded DNA "scaffold" 1 and a plurality of "staple" polynucleotides 2. The single-stranded DNA scaffold 1 is long compared to the hundreds of short polynucleotides 2 used to link together parts of the single-stranded DNA scaffold 1 to form a DNA framework with a maximum dimension of approximately 100 nm.

[0126] The single-stranded DNA scaffold 1 can be a natural genomic sequence, and the polynucleotide 2 is synthesized into a uniquely identifiable base sequence that is complementary to the sequence of different segments of the DNA scaffold 1. This sequence allows the complementary bases on the DNA scaffold 1 and the polynucleotide 2 to hybridize into a double-stranded polynucleotide when the single-stranded DNA scaffold 1 and the polynucleotide 2 are combined and bonded in a suitable aqueous buffer.

[0127] This process forces the DNA scaffold 1 into a precisely defined fold that is held together by the polynucleotide 2 that "staples" together non-adjacent portions of the single-stranded DNA scaffold 1. Figure 1b , 1c As shown in FIG and 1d , the single-stranded DNA scaffold 1 and the polynucleotide 2 self-assemble into a DNA framework 3 formed by a double-stranded polynucleotide.

[0128] like Figure 1b and Figure 1c As shown, the double-stranded polynucleotide DNA framework 3 includes many DNA helices arranged in parallel layers to form a three-dimensional double-stranded polynucleotide structure ( Figure 1c This is done by hybridizing polynucleotide 2 to various parts of the single-stranded DNA scaffold 1 to staple the different parts together. Figure 1c This is achieved in the fully assembled DNA framework 3 shown. (It should be understood that the DNA framework 3 is not usually Figure 1b The intermediate form shown is bonded into Figure 1c The final form is shown, the intermediate form being provided more for the purpose of clearly illustrating the different layers of the DNA framework 3.)

[0129] exist Figure 1b and 1c Also shown is a molecular electronic component 4 attached to the center of the DNA framework 3. The molecular electronic component 4 (e.g., a molecular quantum dot formed by an artificial molecular nanomagnet (e.g., a {Cr7M} ring, such as a hybrid rotaxane including a Cr7M ring)) is formed, and a thiol-modified conductive oligomer 5 is attached to the molecular electronic component 4 by a covalent bond. As will be described below, these conductive oligomers will be used to couple the molecular electronic component 4 to gold nanoparticles for external connection of the molecular electronic device. Two connecting polynucleotides 6 are attached to the conductive oligomer 5 by a covalent bond.

[0130] The linking polynucleotide 6 is synthesized with a uniquely identifiable base sequence to hybridize with a complementary base on the single-stranded DNA scaffold 1 as part of the DNA framework 3. The molecular electronic components 4 each prepared with the linking polynucleotide 6 and the conductive oligomer 5 are purified by polyacrylamide gel electrophoresis or reverse phase chromatography.

[0131] Each linking polynucleotide 6 attached to the molecular electronic component 4 via the conductive oligomer 5 has only one possible hybridization site on the DNA framework 3 (ie hybridizing to the complementary segment of the scaffold 1 ), which enables accurate positioning of the molecular electronic component 4 relative to the DNA framework 3 .

[0132] The molecular electronic component 4 is connected to the DNA frame 3 by combining the molecular electronic component 4 prepared with its conductive oligomer 5 and connecting polynucleotide 6 with the single-stranded DNA scaffold 1 and the "staple" polynucleotide 2. Therefore, when the DNA frame 3 is bonded, the molecular electronic component 4 is positioned in the center of the DNA frame 3.

[0133] (It should be noted that the thiol-modified conductive oligomer 5 does not necessarily have to be attached to the molecular electronic component 4 before the molecular electronic component 4 is connected to the DNA framework 3. For example, the conductive oligomer 5 and the molecular electronic component 4 can be separately provided with the connecting polynucleotide 6 and thus positioned within the framework 3 so that the connection therebetween is formed after assembly of the framework. In another embodiment, the molecular electronic component 4 is functionalized (e.g., with a thiol group) to connect directly to the electrical contact without the need for the addition of an intermediate conductive oligomer.)

[0134] Multiple DNA frameworks 3, each containing a molecular electronic assembly 4 and typically having a total molecular weight of 5 MDa, that can be assembled simultaneously by ligating all components, can be purified from excess staple polynucleotides (whose total molecular weight is typically 10 kDa) using agarose gel purification, size exclusion chromatography or polyethylene glycol precipitation.

[0135] like Figure 1c As shown, once the fully formed DNA framework 3 with the positioned molecular electronic components 4 has been assembled, the gold nanoparticles 7 (which are approximately 60 nm in size) are positioned relative to the DNA framework 3 so as to be carried out as described above by the conductive oligomers attached to the molecular electronic components 4. Figure 1d The tunneling electrical contact to the molecular electronic component 4 is shown. Figure 1c It can be seen that the fully formed DNA framework 3 is shaped to have recesses 8 on both sides for positioning the gold nanoparticles 7 .

[0136] The gold nanoparticles 7 are functionalized by attaching approximately 1000 thiol-modified polynucleotides to each of the gold nanoparticles 7 through covalent bonds, and then purified by filtration. Some of the polynucleotides 2 incorporated into the framework 3 near the recess 8 are synthesized with additional overhanging base sequences to hybridize with complementary bases on the thiol-modified polynucleotides attached to the gold nanoparticles 7.

[0137] This gives these polynucleotide sticky ends for hybridization with the thiol-modified polynucleotides on the gold nanoparticles 7 to connect the gold nanoparticles 7 to the DNA framework 3. Approximately 30 polynucleotides for each gold nanoparticle 7 to be connected are attached to the DNA framework 3 (e.g., form part of the DNA framework). For example, if it is desired that the molecular electronic device have gold nanoparticles 7 of different sizes, these gold nanoparticles can be guided to different sites by different binding sequences on the thiol-modified polynucleotides attached to the gold nanoparticles 7 and the complementary polynucleotides with sticky ends on the DNA framework 3.

[0138] The functionalized gold nanoparticles 7 are introduced after the fully formed DNA framework 3 has been bonded (although in some embodiments, the functionalized gold nanoparticles can be introduced with all other components before the DNA framework 3 is bonded) to dock the gold nanoparticles 7 in the recesses 8 on either side of the DNA framework 3. The connection between the complementary sticky ends of the polynucleotides on the gold nanoparticles 7 and the polynucleotides on the DNA framework 3 positions the gold nanoparticles 7 relative to the DNA framework 3 and therefore relative to the molecular electronic component 4, so that the gold nanoparticles 7 make tunneling electrical connections with the conductive oligomers attached to the molecular electronic component 4 through the thiol-modified peripheral groups on the conductive oligomers covalently bonded to the gold nanoparticles 7. Figure 1d As shown, this electrically connects the gold nanoparticles 7 with the molecular electronic components 4 to form a complete molecular electronic device 10 .

[0139] In order to assemble the molecular electronic device 10 (such as Figure 1d To connect the gold nanoparticles 7 to the circuit as part of a larger (eg, integrated) circuit, electrical connections need to be made to the gold nanoparticles 7.

[0140] Figure 2 A view (imaged by scanning electron microscopy) of a molecular electronic device 10 (with gold nanoparticle contacts 7 particularly evident) deposited on a substrate 11 and connected with platinum wires 12 is shown. To achieve this, the assembled molecular electronic device 10 is first deposited on silicon dioxide on a silicon substrate 11, for example by evaporating an aqueous buffer (salty water) in which the molecular electronic device is assembled. Then, platinum wires 12 are deposited on the substrate using electron beam induced deposition of platinum (with a resolution of a few nanometers) to make electrical connections to the gold nanoparticle contacts 7.

[0141] Figure 3a and 3b Two embodiments of the molecular electronic device 10 are schematically shown. Figure 3a and 3bAs shown, the DNA framework 3 can be designed to control the separation of the gold nanoparticles 7 in the molecular electronic device 10, and thereby control the molecular electronic components ( Figure 3a and 3b The distance is not shown in FIG. Figure 3a In the example, the DNA framework 3 has three double-stranded polynucleotide layers between two gold nanoparticles 7, giving a separation of approximately 5.2 nm, while in Figure 3b In FIG. 5 , the DNA framework 3 has only a monolayer between the gold nanoparticles 7, giving a separation of approximately 1.7 nm.

[0142] Figure 4a and 4b Two embodiments of a molecular electronic device 10 are schematically shown. Figure 4a and 4b The DNA framework is not shown. Figure 4a An embodiment is shown in which the molecular electronic device 10 has two gold nanoparticle contacts 7 (source and drain) attached to the molecular electronic component 4 through corresponding conductive oligomers 9 . Figure 4b An embodiment is shown in which a molecular electronic device 10 has three gold nanoparticle contacts 7 (source, drain and gate) attached to a molecular electronic component 4 through corresponding conductive oligomers 9 that act as current leads and electrostatic gates, respectively. In order to provide electrostatic coupling between the conductive oligomers 9 at the gate end and (e.g., the channel) of the molecular electronic component 4 (e.g., a field effect transistor), the chemical structure of the molecular electronic component 4 is insulating at the location where it is attached to the conductive oligomers 9.

[0143] As can be seen from the above, in at least preferred embodiments, the present invention provides molecular electronic devices and methods of assembling molecular electronic devices. The DNA framework in the molecular electronic device helps provide an atomically precise breadboard for the assembly of molecular components. The use of the DNA framework helps ensure that each device contains a molecular electronic component that is precisely held in place, thereby eliminating the uncertainty in the number, nature, and orientation of bound molecules inherent in current assembly methods for molecular electronic devices.

[0144] The use of DNA frameworks also helps to provide a high-yield process that is reliable, repeatable, reproducible and scalable, and thus produces working devices with confidence.

Claims

1. A molecular electronic device comprising: a framework comprising a plurality of polynucleotides; one or more molecular electronic components; as well as one or more electrical contacts; wherein the one or more molecular electronic components and the one or more electrical contacts are each connected to one or more polynucleotides of the plurality of polynucleotides such that the one or more molecular electronic components and the one or more electrical contacts are positioned relative to the frame and relative to each other to form a coupling between the one or more electrical contacts and the one or more molecular electronic components; The framework comprises a plurality of double-stranded polynucleotide helical layers, and the number of layers of the framework controls the spacing between the one or more molecular electronic components and the one or more electrical contacts.

2. A molecular electronic device according to claim 1, wherein the molecular electronic device comprises a plurality of molecular electronic components, and each of the plurality of molecular electronic components is connected to one or more polynucleotides of the plurality of polynucleotides, so that two or more of the plurality of molecular electronic components are positioned relative to the frame and relative to each other to form a coupling between the two or more molecular electronic components. 3 . The molecular electronic device of claim 1 , wherein the molecular weight of the one or more molecular electronic components is between 100 Daltons (Da) and 10,000 Da. 4 . The molecular electronic device of claim 3 , wherein the molecular weight of the one or more molecular electronic components is between 500 Da and 5,000 Da. 5 . The molecular electronic device of claim 4 , wherein the molecular weight of the one or more molecular electronic components is between 1,000 Da and 3,000 Da. 6 . The molecular electronic device of claim 5 , wherein the molecular weight of the one or more molecular electronic components is 2,600 Da.

7. The molecular electronic device of claim 1 or 2, wherein the one or more molecular electronic components comprise a magnetic heterometallic ring or an antiferromagnetic ring.

8. The molecular electronic device of claim 7, wherein the one or more molecular electronic components comprise a Cr7M ring.

9. The molecular electronic device of claim 1 or 2, wherein the one or more molecular electronic components comprise a rotaxane.

10. The molecular electronic device of claim 1 or 2, wherein the plurality of polynucleotides comprises a longer scaffold polynucleotide and a plurality of shorter staple polynucleotides, wherein the plurality of shorter staple polynucleotides connect different portions of the longer scaffold polynucleotide together.

11. A molecular electronic device according to claim 1 or 2, wherein the frame comprises one or more recesses arranged to respectively locate the one or more electrical contacts.

12. A molecular electronic device according to claim 1 or 2, wherein the molecular electronic device comprises one or more connecting polynucleotides, which are attached to the one or more molecular electronic components and are arranged to connect the one or more molecular electronic components to the one or more polynucleotides among the multiple polynucleotides forming the framework.

13. A molecular electronic device according to claim 10, wherein the multiple polynucleotides forming the framework include one or more framework polynucleotides having single-stranded segments, and wherein the one or more molecular electronic components are connected to the one or more framework polynucleotides by hybridization of one or more connecting polynucleotides with the single-stranded segments of the one or more framework polynucleotides.

14. The molecular electronic device of claim 1 or 2, wherein the one or more molecular electronic components are directly attached to the one or more polynucleotides of the plurality of polynucleotides forming the framework.

15. A molecular electronic device according to claim 10, wherein the one or more molecular electronic components are attached as internal or terminal modifications to one or more polynucleotides among the multiple polynucleotides forming the framework or one or more connecting polynucleotides, and / or the one or more molecular electronic components are inserted as backbone links into the one or more polynucleotides among the multiple polynucleotides forming the framework or into one or more connecting polynucleotides.

16. The molecular electronic device according to claim 1 or 2, wherein the one or more molecular electronic components are attached to the one or more polynucleotides or one or more connecting polynucleotides in the plurality of polynucleotides forming the framework through one or more corresponding covalent bonds.

17. The molecular electronic device of claim 1 or 2, wherein the one or more molecular electronic components are positioned substantially at the center of the frame.

18. The molecular electronic device of claim 1 or 2, wherein the one or more electrical contacts comprise one or more gold nanoparticles having a diameter between 20 nm and 100 nm.

19. The molecular electronic device of claim 18, wherein the one or more gold nanoparticles have a diameter between 40 nm and 80 nm.

20. The molecular electronic device of claim 19, wherein the one or more gold nanoparticles have a diameter between 50 nm and 70 nm.

21. The molecular electronic device of claim 20, wherein the one or more gold nanoparticles have a diameter of 60 nm.

22. A molecular electronic device according to claim 1 or 2, wherein the one or more electrical contacts are fabricated exogenously.

23. A molecular electronic device according to claim 1 or 2, wherein the molecular electronic device comprises one or more connecting polynucleotides, which are attached to the one or more electrical contacts and are arranged to connect the one or more electrical contacts to the one or more polynucleotides among the multiple polynucleotides forming the framework.

24. A molecular electronic device according to claim 23, wherein the multiple polynucleotides forming the framework include one or more framework polynucleotides having single-stranded segments, and wherein the one or more electrical contacts are connected to the one or more framework polynucleotides through hybridization of the one or more connecting polynucleotides with the single-stranded segments of the one or more framework polynucleotides.

25. A molecular electronic device according to claim 1 or 2, wherein the molecular electronic device comprises 1 to 10,000 connecting polynucleotides, which are attached to the one or more electrical contacts, and the multiple polynucleotides forming the framework comprise 1 to 100 polynucleotides, each of which comprises a single-stranded segment hybridized to the multiple connecting polynucleotides attached to the one or more electrical contacts.

26. The molecular electronic device of claim 1 or 2, wherein the one or more electrical contacts are attached to the one or more polynucleotides or one or more connecting polynucleotides of the plurality of polynucleotides forming the framework through one or more corresponding covalent bonds.

27. The molecular electronic device of claim 1 or 2, wherein the coupling comprises a conductive coupling, or the coupling comprises a high resistance coupling.

28. A molecular electronic device according to claim 1 or 2, wherein the coupling is formed by controlling the distance between the one or more molecular electronic components and one or more other molecular electronic components and / or the one or more electrical contacts, or the coupling is formed by forming covalent or other chemical bonds between the one or more molecular electronic components and the one or more electrical contacts.

29. A molecular electronic device according to claim 1 or 2, wherein the coupling allows electrons to tunnel across the coupling.

30. A molecular electronic device according to claim 1 or 2, wherein the molecular electronic device comprises one or more conductive oligomers or other substantially conductive molecules, and the one or more conductive oligomers or other substantially conductive molecules are arranged between the one or more molecular electronic components and the one or more electrical contacts to form a coupling between the one or more molecular electronic components and the one or more electrical contacts or to form a coupling between two or more molecular electronic components.

31. A molecular electronic device according to claim 30, wherein the one or more conductive oligomers or other substantially conductive molecules are attached to the one or more molecular electronic components and / or the one or more electrical contacts by respective covalent bonds.

32. A molecular electronic device according to claim 30, wherein the coupling between the one or more conductive oligomers or other substantially conductive molecules and the one or more molecular electronic components and / or the one or more electrical contacts is formed by controlling the distance between the one or more conductive oligomers or other substantially conductive molecules and the one or more molecular electronic components and / or the one or more electrical contacts.

33. The molecular electronic device of claim 1 or 2, further comprising a substrate on which the frame is deposited.

34. A method of assembling a molecular electronic device, the method comprising: Assembling a framework from multiple polynucleotides; attaching one or more molecular electronic components to one or more polynucleotides of the plurality of polynucleotides; as well as connecting one or more electrical contacts to one or more polynucleotides of the plurality of polynucleotides; and wherein the one or more molecular electronic components and the one or more electrical contacts are each connected to one or more polynucleotides of the plurality of polynucleotides such that the one or more molecular electronic components and the one or more electrical contacts are positioned relative to the frame and relative to each other to form a coupling between the one or more electrical contacts and the one or more molecular electronic components; The framework comprises a plurality of double-stranded polynucleotide helical layers, and the number of layers of the framework controls the spacing between the one or more molecular electronic components and the one or more electrical contacts.

35. A method according to claim 34, wherein the method includes connecting a plurality of molecular electronic components to one or more polynucleotides of the plurality of polynucleotides, and wherein the plurality of molecular electronic components are each connected to one or more polynucleotides of the plurality of polynucleotides such that two or more of the plurality of molecular electronic components are positioned relative to the frame and relative to each other to form a coupling between the two or more molecular electronic components.

36. The method of claim 34 or 35, wherein the plurality of polynucleotides comprises a longer scaffold polynucleotide and a plurality of shorter staple polynucleotides, wherein the method further comprises assembling the framework by linking together different portions of the longer scaffold polynucleotide using the plurality of shorter staple polynucleotides.

37. The method of claim 34 or 35, further comprising ligating the plurality of polynucleotides to assemble the framework.

38. The method according to claim 34 or 35 further includes attaching one or more connecting polynucleotides to the one or more molecular electronic components, and using the one or more connecting polynucleotides attached to the one or more molecular electronic components to connect the one or more molecular electronic components to the one or more polynucleotides in the plurality of polynucleotides forming the frame to position the one or more molecular electronic components relative to the frame, and / or attaching one or more connecting polynucleotides to the one or more electrical contacts, and using the one or more connecting polynucleotides attached to the one or more electrical contacts to connect the one or more electrical contacts to the one or more polynucleotides in the plurality of polynucleotides forming the frame to position the one or more electrical contacts relative to the frame.

39. The method of claim 34 or 35, wherein one or more steps of assembling the molecular electronic device are performed in an aqueous solution.

40. The method of claim 34 or 35, further comprising depositing the molecular electronic device on a substrate.

41. A molecular electronic device obtainable by a method according to any one of claims 34-40.

42. A method of assembling a plurality of molecular electronic devices, the method comprising: Assembling multiple frames, each frame being assembled from multiple polynucleotides; For each frame of the plurality of frames, the method comprises: attaching one or more molecular electronic components to one or more polynucleotides of the plurality of polynucleotides; and connecting one or more electrical contacts to one or more polynucleotides of the plurality of polynucleotides; wherein the one or more molecular electronic components and the one or more electrical contacts are each connected to one or more polynucleotides of the plurality of polynucleotides such that the one or more molecular electronic components and the one or more electrical contacts are positioned relative to the frame and relative to each other to form a coupling between the one or more electrical contacts and the one or more molecular electronic components; The framework comprises a plurality of double-stranded polynucleotide helical layers, and the number of layers of the framework controls the spacing between the one or more molecular electronic components and the one or more electrical contacts.

43. A plurality of molecular electronic devices obtainable by the method according to claim 42.

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