Constructing Nano-Heterostructure with Dual-Site to Boost H2O2 Activation and Regulate the Transformation of Free Radicals.

A major issue with Fenton-like reaction is the excessive consumption of H2O2 caused by the sluggish regeneration rate of low-valent metal, and how to improve the activation efficiency of H2O2 has become a key in current research. Herein, a nano-heterostructure catalyst (1.0-MnCu/C) based on nano-interface engineering is constructed by supporting Cu and MnO on carbon skeleton, and its kinetic rate for the degradation of tetracycline hydrochloride is 0.0436 min-1, which is 2.9 times higher than that of Cu/C system (0.0151 min-1). The enhancement of removal rate results from the introduced Mn species can aggregate and transfer electrons to Cu sites through the electron bridge Mn-N/O-Cu, thus preventing Cu2+ from oxidizing H2O2 to form O2 •-, and facilitating the reduction of Cu2+ and generating more reactive oxygen species (1O2 and ·OH) with stronger oxidation ability, resulting in H2O2 utilization efficiency is 1.9 times as much as that of Cu/C. Additionally, the good and stable practical application capacity in different bodies demonstrates that it has great potential for practical environmental remediation.

Engineering Nanointerfaces of Au25 Clusters for Chaperone-Mediated Peptide Amyloidosis.

Synthetic nanomaterials possessing biomolecular-chaperone functions are good candidates for modulating physicochemical interactions in many bioapplications. Despite extensive research, no general principle to engineer nanomaterial surfaces is available to precisely manipulate biomolecular conformations and behaviors, greatly limiting attempts to develop high-performance nanochaperone materials. Here, we demonstrate that, by quantifying the length (-SCxR±, x = 3-11) and charges (R- = -COO-, R+ = -NH3+) of ligands on Au25 gold nanochaperones (AuNCs), simulating binding sites and affinities of amyloid-like peptides with AuNCs, and probing peptide folding and fibrillation in the presence of AuNCs, it is possible to precisely manipulate the peptides' conformations and, thus, their amyloidosis via customizing AuNCs nanointerfaces. We show that intermediate-length liganded AuNCs with a specific charge chaperone peptides' native conformations and thus inhibit their fibrillation, while other types of AuNCs destabilize peptides and promote their fibrillation. We offer a microscopic molecular insight into peptide identity on AuNCs and provide a guideline in customizing nanochaperones via manipulating their nanointerfaces.

3D nanointerface enhanced optical microfiber for real-time detection and sizing of single nanoparticles.

Portable devices, which can detect and characterize the individual nanoparticles in real time, are of insignificant interest for early diagnosis, homeland security, semiconductor manufacturing and environmental monitoring. Optical microfibers present a good potential in this field, however, are restricted by the sensitivity limit. This study reports the development of a 3D plasmonic nanointerface, which is made of a Cu-BTC framework supporting Cu3-xP nanocrystals, enhancing the optical microfiber for real-time detection and sizing of single nanoparticles. The Cu3-xP nanocrystals are successfully embedded in the 3D Cu-BTC framework. The localized-surface plasmon resonance is tuned to coincide with the evanescent field of the optical microfiber. The 3D Cu-BTC framework, as the scaffold of nanocrystals, confines the local resonance field on the microfiber with three dimensions, at which the binding of target nanoparticles occurs. Based on the evanescent field confinement and surface enhancement by the nanointerface, the optical microfiber sensor overcomes its sensitivity limit, and enables the detection and sizing of the individual nanoparticles. The compact size and low optical power supply of the sensor confirm its suitability as a portable device for the real-time single-nanoparticle characterization, especially for the convenient evaluation of the ultrafine particles in the environment. This work opens up an approach to overcome the sensitivity limit of the optical microfibers, as long with stimulating the portable real-time single-nanoparticle detection and sizing.

Design advanced lithium metal anode materials in high energy density lithium batteries.

Nowadays, the ongoing electrical vehicles and energy storage devices give a great demand of high-energy-density lithium battery. The commercial graphite anode has been reached the limit of the theoretical capacity. Herein, we introduce lithium metal anode to demonstrate the promising anode which can replace graphite. Lithium metal has a high theoretical capacity and the lowest electrochemical potential. Hence, using lithium metal as the anode material of lithium batteries can reach the limit of energy and power density of lithium batteries. However, lithium metal has huge flaw such as unstable SEI layer, volume change and dendrites formation. Therefore, we give a review of the lithium metal anode on its issues and introduce the existing research to overcome these. Besides, we give the perspective that the engineering problems also restrict the commercial use of lithium metal. This review provides the reasonable method to enhance the lithium metal performance and give the development direction for the subsequent research.

Curved Nanointerface Controls the Chiral Effect on Peptide Fibrillation.

Nanostructures with varying functionalities have been engineered to modulate the fibrillation of amyloid-ß (Aß) peptides. Nevertheless, the chirality effect at the curved nanointerfaces is seldom dissected. In this study, we systematically explored the curvature-modulated chiral effect on the regulation of Aß1-42 fibrillation by using l/d-penicillamine-gold nanoparticles (l/d-PGNPs). According to the microscopic and spectroscopic analyses, Aß1-42 fibrillation can be effectively suppressed by more curved (0.2 nm-1, 1/r) d-nanointerface (d-PGNPs5) with notable chiral selectivity, even at a low inhibitor/peptide (I/P) molar ratio (1:100). A greatly alleviated cytotoxic effect of Aß1-42 peptides after the inhibition process is also revealed. The highly curved nanointerface drives the formation of multiple hydrogen bonds and promotes electrostatic interactions with Aß1-42. Importantly, the curved d-nanointerface controls well the spatial arrangement of Pen motifs, making it incompatible with the fibrillation direction of Aß1-42 and thus gaining enhanced efficiency on amyloid fibrillar modulation. This study provides valuable insights into the interactions between chirality and peptide-nanointerface effects, which are crucial for the development of inhibitors in anti-ß-amyloidosis.

Ultrasensitive deafness gene DNA hybridization detection employing a fiber optic Mach-Zehnder interferometer: Enabled by a black phosphorus nanointerface.

The rapid and efficient detection of deafness gene DNA plays an important role in the clinical diagnosis of deafness diseases. This study demonstrates the ultrasensitive detection of complementary DNA (cDNA) by employing a nanointerface-sensitized fiber optic biosensor. The sensor consists of SMF-TNCF-MMF-SMF (abbreviated as STMS) structure with lateral offset. Besides, it is functionalized with a nanointerface of black phosphorus (BP) to enhance the light-matter interaction and eventually improve the sensing performances. Relying on this nanointerface-sensitized sensor, we successfully realize the in-situ detection of cDNA at concentrations ranging from 1 pM to 1 µM, with a sensitivity of 0.719 nm/lgM. The limit of detection (LOD) is as low as 0.24 pM, which is at least two orders of magnitude lower than those of existing methods. The sensor exhibits the advantages of simple operation, fast response, label-free measurement, excellent repeatability, and high selectivity. Our contribution suggests a convenient approach for deafness gene DNA detection and can be extended for general ultra-low concentration DNA detection applications.

Modifying charge transfer between rhodium and ceria for boosted hydrogen oxidation reaction in alkaline electrolyte.

Sluggish kinetics of hydrogen oxidation reaction (HOR) in alkaline solution has restricted the rapid development of hydrogen economy. Constructing catalyst with metal-oxide heterostructures can enhance HOR performance; however, little studies concentrate on charge transfer between them, and the corresponding effects on reactions remain unclear. Herein, we report charge-transfer-adjustable CeO2/Rh interfaces uniformly dispersed on multiwalled carbon nanotube (CNT), which exhibit excellent alkaline HOR performance. Results confirm that the charge transfer from Rh to CeO2 could be conveniently tuned via thermal treatment. Consequently, the adsorption free energies of H* in Rh sites and OH* adsorption strength in CeO2 could be adjusted, as corroborated by density functional theory study. The optimized CeO2/Rh interfaces exhibit an exchange current density and a mass-specific kinetic current of 0.53 mA cmPGM-2 and 830 A gPGM-1 at an overpotential of 50 mV, respectively, which surpasses most of the advanced noble-metal-based electrocatalysts. This work provides a new insight of harnessing charge transfer of heterostructure to enhance catalytic activities.

Microfluidic Biosensor Decorated with an Indium Phosphate Nanointerface for Attomolar Dopamine Detection.

Developing functional materials that directly integrate into miniaturized devices for sensing applications is essential for constructing the next-generation point-of-care system. Although crystalline structure materials such as metal organic frameworks are attractive materials exhibiting promising potential for biosensing, their integration into miniaturized devices is limited. Dopamine (DA) is a major neurotransmitter released by dopaminergic neurons and has huge implications in neurodegenerative diseases. Integrated microfluidic biosensors capable of sensitive monitoring of DA from mass-limited samples is thus of significant importance. In this study, we developed and systematically characterized a microfluidic biosensor functionalized with the hybrid material composed of indium phosphate and polyaniline nanointerfaces for DA detection. Under the flowing operation, this biosensor displays a linear dynamic sensing range going from 10-18 to 10-11 M and a limit of detection (LOD) value of 1.83 × 10-19 M. In addition to the high sensitivity, this microfluidic sensor showed good selectivity toward DA and high stability (>1000 cycles). Further, the reliability and practical utility of the microfluidic biosensor were demonstrated using the neuro-2A cells treated with the activator, promoter, and inhibiter. These promising results underscore the importance and potential of microfluidic biosensors integrated with hybrid materials as advanced biosensors systems.

Nanointerface engineering Z-scheme CuBiOS@CuBi2O4 heterojunction with OS interpenetration for enhancing photocatalytic hydrogen peroxide generation and accelerating chromium(VI) reduction.

Designing a core-shell nanointerface is beneficial for enhancing the photocatalytic performance of hydrogen peroxide (H2O2) production. Hence, a direct Z-scheme one-dimensional (1 D) CuBiOS@CuBi2O4 nanorods with a core (oxide)-shell (sulfide) nanostructure and OS interpenetrated nanointerface was controllably synthesized through in-situ anion exchange. The formation of OS interpenetration at the heterogeneous interface with surface oxygen vacancies could effectively boost light absorption, reduce the interface contact resistance, facilitate band bending, and thus enhance charge separation and transfer as a "bridge". The as-prepared catalyst with tunable OS nanointerface greatly improved the photocatalytic performances in the H2O2 production with a yield of 201.9 µmol·L-1 and the in-situ generated H2O2 effectively accelerated the reduction of chromium(VI) (Cr(VI), 95.4% within 15 min). The excellent performances were due to the OS interpenetration with rich oxygen vacancies and unique shell-core structure with intimate contact inter-doping nanointerface. Moreover, the photocatalytic mechanism was discussed in detail. This work might provide a guideline in the design and construction of high-performance catalysts with well-defined nanointerface for various applications.

Shape-Programmable Interfacial Solar Evaporator with Salt-Precipitation Monitoring Function.

Interfacial solar evaporators (ISEs) for seawater desalination have garnered enormous attention in recent decades due to global water scarcity. Despite the progress in the energy conversion efficiency and production rate of ISE, the poor portability of large-area ISE during transportation as well as the clogging of water transport pathways by precipitated salts during operation remain grand challenges for its fielded applications. Here, we designed an ISE with high energy conversion efficiency and shape morphing capability by integrating carbon nanotube (CNT) fillers with a light-responsive shape memory polymer (SMP, cross-linked polycyclooctene (cPCO)). Utilizing the shape memory effect, our ISE can be folded to an origami with 1/9 of its original size to save space for transportation and allow for on-demand unfolding upon sunlight irradiation when deployed in service. In addition, the ISE is equipped with a real-time clogging monitoring function by measuring the capacitance of the electric double layer (EDL) formed at the evaporator/seawater nanointerface. Due to its good energy conversion efficiency, high portability, and clogging monitoring capability, we envisage our ISE as a promising selection in solar evaporation technologies.

CO Oxidation at Near-Ambient Temperatures over TiO2-Supported Pd-Cu Catalysts: Promoting Effect of Pd-Cu Nanointerface and TiO2 Morphology.

Significant improvement of the catalytic activity of palladium-based catalysts toward carbon monoxide (CO) oxidation reaction has been achieved through alloying and using different support materials. This work demonstrates the promoting effects of the nanointerface and the morphological features of the support on the CO oxidation reaction using a Pd-Cu/TiO2 catalyst. Pd-Cu catalysts supported on TiO2 were synthesized with wet chemical approaches and their catalytic activities for CO oxidation reaction were evaluated. The physicochemical properties of the prepared catalysts were studied using standard characterization tools including SEM, EDX, XRD, XPS, and Raman. The effects of the nanointerface between Pd and Cu and the morphology of the TiO2 support were investigated using three different-shaped TiO2 nanoparticles, namely spheres, nanotubes, and nanowires. The Pd catalysts that are modified through nanointerfacing with Cu and supported on TiO2 nanowires demonstrated the highest CO oxidation rates, reaching 100% CO conversion at temperature regime down to near-ambient temperatures of ~45 °C, compared to 70 °C and 150 °C in the case of pure Pd and pure Cu counterpart catalysts on the same support, respectively. The optimized Pd-Cu/TiO2 nanowires nanostructured system could serve as efficient and durable catalyst for CO oxidation at near-ambient temperature.

Chlorine-assisted synthesis of CuCo2S4@(Cu,Co)2Cl(OH)3 heterostructures with an efficient nanointerface for electrocatalytic oxygen evolution.

The demand for sustainable energy sources urges the development of efficient and earth-abundant electrocatalysts. Herein, chlorine assisted ion-exchange and in-situ sulfurization processes were combined to construct CuCo2S4@(Cu,Co)2Cl(OH)3 heterostructures from Cu(OH)2 nanoarrays. Chlorine element in the cobalt source stimulated the formation of (Cu,Co)2Cl(OH)3 precursor, and further facilitated partial transformation of the precursor to CuCo2S4 on the surface to achieve composite structure. The mixed valences of Co element (Co3+ in CuCo2S4 and Co2+ in (Cu,Co)2Cl(OH)3) and OS interpenetrated nanointerface in the composite catalysts provided low electron transfer resistance for good alkaline oxygen evolution reaction (OER) activities. In 1 mol L-1 KOH electrolyte, the overpotentials of the optimal composite catalyst reached 253 and 290 mV respectively at the current density of 20 and 50 mA cm-2, which is comparable to the activity of commercial Ir/C (281 mV@20 mA cm-2). These findings could provide opportunities for designing effective and inexpensive composite electrocatalysts through nanointerface engineering strategy.

Enhanced Hemocompatibility of a Direct Chemical Vapor Deposition-Derived Graphene Film.

A wide range of biomedical devices are being used to treat cardiovascular diseases, and thus they routinely come into contact with blood. Insufficient hemocompatibility has been found to impair the functionality and safety of these devices through the activation of blood coagulation and the immune system. Numerous attempts have been made to develop surface modification approaches of the cardiovascular devices to improve their hemocompatibility. However, there are still no ideal "blood-friendly" coating materials, which possess the desired hemocompatibility, tissue compatibility, and mechanical properties. As a novel multifunctional material, graphene has been proposed for a wide range of biomedical applications. The chemical inertness, atomic smoothness, and high durability make graphene an ideal candidate as a surface coating material for implantable devices. Here, we evaluated the hemocompatibility of a graphene film prepared on quartz glasses (Gra-glasses) from a direct chemical vapor deposition process. We found that the graphene coating, which is free of transfer-mediating polymer contamination, significantly suppressed platelet adhesion and activation, prolonged coagulation time, and reduced ex vivo thrombosis formation. We attribute the excellent antithrombogenic properties of the Gra-glasses to the low surface roughness, low surface energy (especially the low polar component of the surface energy), and the negative surface charge of the graphene film. Given these excellent hemocompatible properties, along with its chemical inertness, high durability, and molecular impermeability, a graphene film holds great promise as an antithrombogenic coating for next-generation cardiovascular devices.

Acceleration of DNA Hybridization Chain Reactions on 3D Nanointerfaces of Magnetic Particles and Their Direct Application in the Enzyme-Free Amplified Detection of microRNA.

Accelerated DNA hybridization chain reactions (HCRs) using DNA origami as a scaffold have received considerable attention in dynamic DNA nanotechnology. However, tailor-made designs are essential for DNA origami scaffolds, hampering the practical application of accelerated HCRs. Here, we constructed the semilocalized HCR and localized HCR systems using magnetic beads (MBs) as a simple scaffold to explore them for the enzyme-free miR-21 detection. The semilocalized HCR system relied on free diffusing one hairpin DNA and MBs immobilized with another hairpin DNA, and the localized HCR system relied on MBs coimmobilized with two hairpin DNAs. We demonstrated that the DNA density on MBs plays a critical role in HCR kinetics and limit of detection (LOD). Among semilocalized HCR systems, MBs with a medium DNA density showed a faster HCR and lower LOD (10 pM) than the diffusive (conventional) HCR system (LOD: 86 pM). In contrast, the HCR further accelerated for the localized HCR systems as the DNA density increased. The localized HCR system with the highest DNA density showed the fastest HCR and the lowest LOD (533 fM). These findings are of great importance for the rational design of accelerated HCRs using simple scaffolds for practical applications.

Ordered Fibril Arrays in Osteons Promote the Multidirectional Nanodeflection of Cracks: In Situ AFM Imaging.

The high fracture resistance of cortical bone is not completely understood across its complex hierarchical structure, especially on micro- and nanolevels. Here, a novel in situ bending test combined with atomic force microscopy (AFM) is utilized to assess the micro-/nanoscale failure behavior of cortical bone under the external load. Unlike the smoother crack path in the transverse direction, the multilevel composite material model endows the longitudinal direction to show multilevel Y-shaped cracks with more failure interfaces for enhancing the fracture resistance. In the lamellae, the nanocracks originating from the interfibrillar nanointerface deflect multidirectionally at certain angles related to the periodic ordered arrangement of the mineralized collagen fibril (MCF) arrays. The ordered MCF arrays in the lamellae may use the nanodeflection of the dendritic nanocracks to adjust the direction of the crack tip, which subsequently reaches the interlamellae to sharply deflect and finally form a zigzag path. This work provides an insight into the relationship between the structure and the function of bone at a multilevel under load, specifically the role of the ordered MCF arrays in the lamellar structure.

Metal-Free, Graphene Oxide-Based Tunable Soliton and Plasmon Engineering for Biosensing Applications.

The quest for auxiliary plasmonic materials with lossless properties began in the past decade. In the current study, a unique plasmonic response is demonstrated from a stratified high refractive index (HRI)-graphene oxide (GO) and low refractive index (LRI)-polymethyl methacrylate (PMMA) multistack. Graphene oxide plasmon-coupled emission (GraPE) reveals the existence of strong surface states on the terminating layer of the photonic crystal (PC) framework. The chemical defects in GO thin film are conducive for unraveling plasmon hybridization within and across the multistack. We have achieved a unique assortment of metal-dielectric-metal (MDM) ensuing a zero-normal steering emission on account of solitons as well as directional GraPE. This has been theoretically established and experimentally demonstrated with a metal-free design. The angle-dependent reflectivity plots, electric field energy (EFI) profiles, and finite-difference time-domain (FDTD) analysis from the simulations strongly support plasmonic modes with giant Purcell factors (PFs). The architecture presented prospects for the replacement of metal-dependent MDM and surface plasmon-coupled emission (SPCE) technology with low cost, easy to fabricate, tunable soliton [graphene oxide plasmon-coupled soliton emission (GraSE)], and plasmon [GraPE] engineering for diverse biosensing applications. The superiority of the GraPE platform for achieving 1.95 pg mL-1 limit of detection of human IFN-γ is validated experimentally. A variety of nanoparticles encompassing metals, intermetallics, rare-earth, and low-dimensional carbon-plasmonic hybrids were used to comprehend PF and cavity hot-spot contribution resulting in 900-fold fluorescence emission enhancements on a lossless substrate, thereby opening the door to unique light-matter interactions for next-gen plasmonic and biomedical technologies.

W doping dominated NiO/NiS2 interfaced nanosheets for highly efficient overall water splitting.

Constructing high-efficiency electrocatalysts is vital towards electrocatalytic water splitting, but it remains a challenge. Although Ni-based materials have drawn extensive attention as highly active catalysts, the relatively limited electroactive sites in Ni-based catalysts still remains a great issue. In order to further boost the electrocatalytic performances, heteroatom doping and interface engineering are usually adopted for modification. Here, a new strategy is developed to construct W doped NiO/NiS2 interfaced nanosheets directly on carbon sheet, which is working as efficient and bifunctional electrocatalysts for overall water splitting. W doped NiO nanosheets are directly constructed on the carbon sheet by the hydrothermal and annealing processes. After that, W-NiO was subjected to Ar plasma assisted sulfuration treatment for forming W doped NiO/NiS2 interfaced nanosheets. Based on systematic investigations, we find that W doping can effectively induce the modified electronic structure of Ni to boost the intrinsic activities in NiO/NiS2. Further, forming NiO/NiS2 nanointerfaces can also provide rich electroactive sites and boost the charge transfer rate. Consequently, W doped NiO/NiS2 exhibits the much enhanced performances for overall water splitting. As a bifunctional electrode, W-NiO/NiS2 demonstrates a remarkable activity with a 1.614 V cell voltage at 10 mA cm-2 for overall water splitting.

Constructing Fe-MOF-Derived Z-Scheme Photocatalysts with Enhanced Charge Transport: Nanointerface and Carbon Sheath Synergistic Effect.

Creatively constructing Z-scheme composites is a promising and common strategy for designing effective photocatalyst systems. Herein, we synthesized Z-scheme Fe2O3@Ag-ZnO@C heterostructures from the Fe-MOFs and applied it to photodegradation of tetracycline and methylene blue pollutants in wastewater. The optimized sample exhibits a remarkable performance as well as stability under visible light irradiation. The calculating and experimental results demonstrate that the Fe2O3@ZnO nanointerface and carbon sheath together boost the transfer efficiency of photogenerated carriers and absorption ability, thereby improving the photocatalytic activity. Furthermore, detailed mechanism investigation reveals the pivotal role of reactive oxygen species (•OH and •O2-) generated, resulting in remarkable performance. In addition, cell biology experiments reveal that the wastewater after photocatalytic treatment has good biological compatibility, which is important for applications. This work provides valuable information for constructing high-performance Z-scheme photocatalysts from MOFs for environmental treatment.

Biodeposited Nano-CdS Drives the In Situ Growth of Highly Dispersed Sulfide Nanoparticles during Pyrolysis for Enhanced Oxygen Evolution Reaction.

A novel, efficient, and stable graphene-based composite oxygen evolution reaction (OER) catalyst, BG@Ni/Ni3S2, was designed via high-specificity, low-cost biosynthesis and efficient electrostatic self-assembly. In the synthetic process, bacterial cells containing biodeposited CdS nanocrystals, graphene oxide (GO), and Ni2+ ions are assembled into a sandwich-type hybrid precursor. The nanosized sulfur source drives in situ sulfidation during pyrolysis, which induces the uniform formation and growth of Ni/Ni3S2 composite nanoparticles (NPs) on the graphene substrate. Benefiting from the high specific surface area and uniform distribution of NPs, the catalyst has a large number of exposed active sites and exhibits rapid mass transfer. In addition, the skeleton composed of a conductive carbon matrix and metallic Ni-Ni network ensures the excellent electron transfer during the OER, and the synergistic effect of Ni0 and Ni3S2 further optimizes the electronic structure and accelerates the OER kinetics. The dominant catalytic sites at the nanointerface between Ni0 and Ni3S2 provide favorable thermodynamic conditions for the adsorption of OER intermediates. As a result, BG@Ni/Ni3S2 exhibits efficient catalytic performance for the OER: the overpotential and Tafel slope are only 320 mV at 100 mA cm-2 and 41 mV dec-1, respectively. This work provides a novel understanding of the intrinsic activity of transition metal sulfide composites and a biological-based design for OER catalysts.

Simple Single-Legged DNA Walkers at Diffusion-Limited Nanointerfaces of Gold Nanoparticles Driven by a DNA Circuit Mechanism.

We designed and prepared a single-legged DNA walker that relies on the creation of a simple diffusion-limited nanointerface on a gold nanoparticle (DNA/PEG(+)-GNP) track co-modified with fluorescence-labeled hairpin DNA and poly(ethylene glycol) (PEG) containing a positively charged amino group at one end. The movement of our single-legged DNA walker is driven by an enzyme-free DNA circuit mechanism through cascading toehold mediated DNA displacement reactions (TMDRs) using fuel hairpin DNAs. The acceleration of TMDRs was observed for the DNA/PEG(+)-GNP track through electrostatic interaction between the positively charged track and negatively charged DNAs, resulting in the acceleration of the DNA circuit and amplification of the fluorescence signal. Furthermore, the DNA/PEG(+)-GNP track allowed autonomous and persistent movement of a walker DNA strand on the same GNP track, because the intraparticle DNA circuit occurred preferentially by preventing diffusion of the negatively charged free walker DNA strand from near the positively charged tracks into solution through electrostatic interaction. Based on comparative study of kinetics of TMDRs and DNA walking behaviors, it is to be noted that the DNA/PEG(+)-GNP track showed the fastest DNA circuit reaction (walking rate) and the largest number of steps taken by the walker DNA strand compared to other GNP tracks with varying nanointerfaces that differ in terms of their type of charges (no and negative charges), density of positive charges, and number of hairpin DNAs per GNP track. These facts reveal that the positive charges on the GNP track play an important role in the acceleration of the DNA circuit, as well as the successful walking motion of the single-legged DNA strand. By using the fluorescence signal amplification functions, our single-legged DNA walker could be applied directly and successfully to enzyme-free miRNA-detection systems. The miRNA-detection system provided higher discrimination of other mismatched miRNAs and higher sensitivity (the lowest LOD: 4.0 pM) when compared to other miRNA-detection systems based on other GNP tracks without positive charges. Unlike existing single-legged DNA walkers, our single-legged DNA walkers do not require complex processes, such as immobilization of the walker DNA strand on the tracks and precise adjustment of the sequence of walker DNA. Therefore, our strategy, based on the creation of diffusion-limited nanointerfaces, has enormous potential for the applications of single-legged DNA walkers to biosensors, bioimaging, and computing.