Contact Transfer Printing of Side Edge Prefunctionalized Nanoplasmonic Arrays for Flexible microRNA Biosensor

RNA-Cleaving DNAzyme-Based Amplification Strategies for Biosensing and Therapy

Since their first discovery in 1994, DNAzymes have been extensively applied in biosensing and therapy that act as recognition elements and signal generators with the outstanding properties of good stability, simple synthesis, and high sensitivity. One subset, RNA-cleaving DNAzymes, is widely employed for diverse applications, including as reporters capable of transmitting detectable signals. In this review, the recent advances of RNA-cleaving DNAzyme-based amplification strategies in scaled-up biosensing are focused, the application in diagnosis and disease treatment are also discussed. Two major types of RNA-cleaving DNAzyme-based amplification strategies are highlighted, namely direct response amplification strategies and combinational response amplification strategies. The direct response amplification strategies refer to those based on novel designed single-stranded DNAzyme, and the combinational response amplification strategies mainly include two-part assembled DNAzyme, cascade reactions, CHA/HCR/RCA, DNA walker, CRISPR-Cas12a and aptamer. Finally, the current status of DNAzymes, the challenges, and the prospects of DNAzyme-based biosensors are presented.

Quantum Plasmonics: Energy Transport Through Plasmonic Gap

At the interfaces of metal and dielectric materials, strong light-matter interactions excite surface plasmons; this allows electromagnetic field confinement and enhancement on the sub-wavelength scale. Such phenomena have attracted considerable interest in the field of exotic material-based nanophotonic research, with potential applications including nonlinear spectroscopies, information processing, single-molecule sensing, organic-molecule devices, and plasmon chemistry. These innovative plasmonics-based technologies can meet the ever-increasing demands for speed and capacity in nanoscale devices, offering ultrasensitive detection capabilities and low-power operations. Size scaling from the nanometer to sub-nanometer ranges is consistently researched; as a result, the quantum behavior of localized surface plasmons, as well as those of matter, nonlocality, and quantum electron tunneling is investigated using an innovative nanofabrication and chemical functionalization approach, thereby opening a new era of quantum plasmonics. This new field enables the ultimate miniaturization of photonic components and provides extreme limits on light-matter interactions, permitting energy transport across the extremely small plasmonic gap. In this review, a comprehensive overview of the recent developments of quantum plasmonic resonators with particular focus on novel materials is presented. By exploring the novel gap materials in quantum regime, the potential quantum technology applications are also searched for and mapped out.

Large-Area Nanopatterning Based on Field Alignment by the Microscale Metal Mask for the Etching Process

Recently, researchers have dedicated efforts toward producing large-area nanostructures using advanced lithography techniques and state-of-the-art etching methods. However, these processes involve challenges such as the diffraction limit and an unintended etching profile. In this work, we demonstrate large-area nanopatterning on a silicon substrate using the microscale metal mask by meticulous optimization of the etching process. Around the vertex of a microscale metal mask, a locally induced electric field is generated by a bias voltage applied on a silicon mold. We utilize this field to change the trajectory of reactive ions and their effect flux, thus providing a controllable bowing effect. The results are analyzed by both numerical simulations and experiments. Based on the field alignment by the metal mask for the etching (FAME) process, we demonstrate the fabrication of 378 nm-size nanostructure patterns which translate to a size reduction of 63% from 1 μm-size mask patterns on a wafer by optimization of the processes. This is much higher than the undercut (∼37%) usually achieved by a typical non-Bosch process under similar etching conditions. The optimized nanostructure is used as a mold for the transfer printing of nanostructure arrays on a flexible substrate to demonstrate that it enables the functionality of FAME-processed nanostructures.

Methodological Approaches to Study Extracellular Vesicle miRNAs in Epstein⁻Barr Virus-Associated Cancers

Epstein Barr-virus (EBV) was the first virus identified to be associated with human cancer in 1964 and is found ubiquitously throughout the world's population. It is now established that EBV contributes to the development and progression of multiple human cancers of both lymphoid and epithelial cell origins. EBV encoded miRNAs play an important role in tumor proliferation, angiogenesis, immune escape, tissue invasion, and metastasis. Recently, EBV miRNAs have been found to be released from infected cancer cells in extracellular vesicles (EVs) and regulate gene expression in neighboring uninfected cells present in the tumor microenvironment and possibly at distal sites. As EVs are abundant in many biological fluids, the viral and cellular miRNAs present within EBV-modified EVs may serve as noninvasion markers for cancer diagnosis and prognosis. In this review, we discuss recent advances in EV isolation and miRNA detection, and provide a complete workflow for EV purification from plasma and deep-sequencing for biomarker discovery.

"Self-Peel-Off" Transfer Produces Ultrathin Polyvinylidene-Fluoride-Based Flexible Nanodevices

Here, a new strategy, self-peel-off transfer, for the preparation of ultrathin flexible nanodevices made from polyvinylidene-fluoride (PVDF) is reported. In this process, a functional pattern of nanoparticles is transferred via peeling from a temporary substrate to the final PVDF film. This peeling process takes advantage of the differences in the work of adhesion between the various layers (the PVDF layer, the nanoparticle-pattern layer and the substrate layer) and of the high stresses generated by the differential thermal expansion of the layers. The work of adhesion is mainly guided by the basic physical/chemical properties of these layers and is highly sensitive to variations in temperature and moisture in the environment. The peeling technique is tested on a variety of PVDF-based functional films using gold/palladium nanoparticles, carbon nanotubes, graphene oxide, and lithium iron phosphate. Several PVDF-based flexible nanodevices are prepared, including a single-sided wireless flexible humidity sensor in which PVDF is used as the substrate and a double-sided flexible capacitor in which PVDF is used as the ferroelectric layer and the carrier layer. Results show that the nanodevices perform with high repeatability and stability. Self-peel-off transfer is a viable preparation strategy for the design and fabrication of flexible, ultrathin, and light-weight nanodevices.

Optimally Functionalized Adhesion for Contact Transfer Printing of Plasmonic Nanostructures on Flexible Substrate

This paper demonstrates a facile method to achieve high yield and uniform fabrication for the transfer printing of nanoplasmonic structures on a flexible substrate by providing novel understanding on adhesion layers. The mercapto alkyl carboxylic acids and the alkyl dithiols are used as functionalized adhesion layers and further optimized by controlling the terminal group as well as the length and composition of the functionalization on flat and nanostructured gold surfaces. Our approach of optimized adhesion has been successfully implemented to the transfer printing of functionalized gold nanostructure arrays, thus producing much higher yield of 97.6% and uniform fabrication of nanostructures on a flexible substrate and enabling applications such as flexible nanoplasmonic devices and biosensing platforms.