Metallic Conductive Nanowires Elaborated by PVD Metal Deposition on Suspended DNA Bundles

Towards atom manufacturing with framework nucleic acids

Atom manufacturing has become a blooming frontier direction in the field of material and chemical science in recent years, focusing on the fabrication of functional materials and devices with individual atoms or with atomic precision. Framework nucleic acids (FNAs) refer to nanoscale nucleic acid framework structures with novel properties distinct from those of conventional nucleic acids. Due to their ability to be precisely positioned and assembled at the nanometer or even atomic scale, FNAs are ideal materials for atom manufacturing. They hold great promise for the bottom-up construction of electronic devices by precisely arranging and integrating building blocks with atomic or near-atomic precision. In this review, we summarize the progress of atom manufacturing based on FNAs. We begin by introducing the atomic-precision construction of FNAs and the intrinsic electrical properties of DNA molecules. Then, we describe various approaches for the fabrication of FNAs templated materials and devices, which are classified as conducting, insulating, or semiconducting based on their electrical properties. We highlight the role of FNAs in the fabrication of functional electronic devices with atomic precision, as well as the challenges and opportunities for atom manufacturing with FNAs.

Bottom-Up Fabrication of DNA-Templated Electronic Nanomaterials and Their Characterization

Bottom-up fabrication using DNA is a promising approach for the creation of nanoarchitectures. Accordingly, nanomaterials with specific electronic, photonic, or other functions are precisely and programmably positioned on DNA nanostructures from a disordered collection of smaller parts. These self-assembled structures offer significant potential in many domains such as sensing, drug delivery, and electronic device manufacturing. This review describes recent progress in organizing nanoscale morphologies of metals, semiconductors, and carbon nanotubes using DNA templates. We describe common substrates, DNA templates, seeding, plating, nanomaterial placement, and methods for structural and electrical characterization. Finally, our outlook for DNA-enabled bottom-up nanofabrication of materials is presented.

Three-dimensional nanolithography guided by DNA modular epitaxy

Lithographic scaling of periodic three-dimensional patterns is critical for advancing scalable nanomanufacturing. Current state-of-the-art quadruple patterning or extreme-ultraviolet lithography produce a line pitch down to around 30 nm, which might be further scaled to sub-20 nm through complex post-fabrication processes. Herein, we report the use of three-dimensional (3D) DNA nanostructures to scale the line pitch down to 16.2 nm, around 50% smaller than state-of-the-art results. We use a DNA modular epitaxy approach to fabricate 3D DNA masks with prescribed structural parameters (geometry, pitch and critical dimensions) along a designer assembly pathway. Single-run reactive ion etching then transfers the DNA patterns to a Si substrate at a lateral critical dimension of 7 nm and a vertical critical dimension of 2 nm. The nanolithography guided by DNA modular epitaxy achieves a smaller pitch than the projected values for advanced technology nodes in field-effect transistors, and provides a potential complement to the existing lithographic tools for advanced 3D nanomanufacturing.

DNA-Based Fabrication for Nanoelectronics

The bottom-up DNA-templated nanoelectronics exploits the unparalleled self-assembly properties of DNA molecules and their amenability with various types of nanomaterials. In principle, nanoelectronic devices can be bottom-up assembled with near-atomic precision, which compares favorably with well-established top-down fabrication process with nanometer precision. Over the past decade, intensive effort has been made to develop DNA-based nanoassemblies including DNA-metal, DNA-polymer, and DNA-carbon nanotube complexes. This review introduces the history of DNA-based fabrication for nanoelectronics briefly and summarizes the state-of-art advances of DNA-based nanoelectronics. In particular, the most widely applied characterization techniques to explore their unique electronic properties at the nanoscale are described and discussed, including scanning tunneling microscopy, conductive atomic force microscopy, and Kelvin probe force microscopy. We also provide a perspective on potential applications of DNA-based nanoelectronics.

Phase-Regulated Sensing Mechanism of MoS2 Based Nanohybrids toward Point-of-Care Prostate Cancer Diagnosis

Alpha-methylacyl-CoA racemase (AMACR) has been proven to be consistently overexpressed in prostate cancer epitheliums, and is expected to act as a positive biomarker for the diagnosis of prostate carcinoma in clinical practice. Here, a strategy for specific determination of AMACR in real human serum by using an electrochemical microsensor system is presented. In order to implement the protocol, a self-organized nanohybrid consisting of metal nanopillars in a 2D MoS₂ matrix is developed as material for the sensing interface. The testing signal outputs are strongly enhanced with the presence of the nanohybrids owing to that the metal pillars provide an efficient mass difussion and electron transfer path to the MoS₂ film surface. Furthermore, the phase-regulated sensing mechanism over MoS₂ is noticed and demonstrated by density functional theory calculation and experiments. The explored MoS₂ based nanohybrids are employed for the fabrication of an electrochemical microsensor, presenting good linear relationship in both ng µL^-1 and pg µL^-1 ranges for AMACR quantification. The sampling analysis of human serum indicates that this microsensor has good diagnostic specificity and sensitivity toward AMACR. The proposed electrochemical microsensor system also demonstrates the advantages of convenience, cost-effectiveness, and disposability, resulting in a potential integrated microsystem for point-of-care prostate cancer diagnosis.

Surface Metallization of Porous Polymer Materials for Multifunctional Applications

Porous materials have attracted great interest in recent years, and a variety of surface modification methods have been developed to endow porous materials with multifunctional applications. Herein, multifunctional porous materials are fabricated based on surface metallization. Metallized sponges with Ag and Cu are highly hydrophobic and are still hydrophobic under oil. The metallized sponges selectively adsorb oils from oil/water mixtures and can completely remove oils from water. We further demonstrate continuous oil-water separation by the metallized sponges with the aid of a peristaltic pump. The Ag-metallized materials show high catalytic performance for both chemical reduction and dye degradation. The catalytic reduction efficiency of 4-nitrophenol reaches 97.7% within 60 min and remains as high as 96% after 15 cycles. Moreover, the metallized materials show 99.99% bactericidal efficiency for both Staphylococcus aureus and Escherichia coli. Particularly, the Cu-metallized materials exhibit stable conductivity under deformation; and metal patterns are realized via the metallization method combined with a patterned mask, which may provide a feasible approach for flexible electronics. This work provides a versatile method to introduce metal coatings to porous materials, broadening the applications of porous materials.

Review of the Electrical Characterization of Metallic Nanowires on DNA Templates

The use of self-assembly techniques may open new possibilities in scaling down electronic circuits to their ultimate limits. Deoxyribonucleic acid (DNA) nanotechnology has already demonstrated that it can provide valuable tools for the creation of nanostructures of arbitrary shape, therefore presenting an ideal platform for the development of nanoelectronic circuits. So far, however, the electronic properties of DNA nanostructures are mostly insulating, thus limiting the use of the nanostructures in electronic circuits. Therefore, methods have been investigated that use the DNA nanostructures as templates for the deposition of electrically conducting materials along the DNA strands. The most simple such structure is given by metallic nanowires formed by deposition of metals along the DNA nanostructures. Here, we review the fabrication and the characterization of the electronic properties of nanowires, which were created using these methods.