Flexible Nanostructures Research Articles

Flexible hybrid nanostructured chemiresistive sensing platform for low-temperature trace hydrogen detection

The prevalence of hydrogen (H2) utilization across commercial and industrial sectors has spurred the innovation of various H2 gas sensors. However, their practical implementation has been hindered by issues such as cost inefficiency, low sensitivity, inadequate selectivity, and limitations in low-temperature sensing capabilities. Consequently, the development of a sensor capable of surmounting these challenges is paramount for widespread adoption. In this study, a cost-effective approach has been used to fabricate a flexible hybrid nanostructured platform on polyethylene terephthalate (PET) substrate incorporating a combination of zinc oxide (ZnO), titanium oxide (TiO2), and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). This platform has undergone meticulous morphological characterization and comprehensive evaluation for H2 gas sensing applications at both room temperature and 50˚C. The results reveal that the developed PEDOT:PSS/TiO2/ZnO NWs sensor exhibits superior H2 gas sensing characteristics with 141 % and 163 % higher response by proportions at 100 ppb and 100 ppm, respectively outperforming other prepared devices in the same environment. Thus demonstrating exceptional sensitivity of 0.448 %/ppm with three cycle repeatability, H2 selectivity and nine months of stability at low temperatures. Moreover, the sensor has an ultralow limit of detection (LOD) of ∼9 ppt, along with a rapid response time of 65 s and a recovery time of 42 s at an H2 concentration of 100 ppb. This research drives the advancement of efficient, rapid-responsive, and discerning trace detection of H2 gas at low temperatures.

Surface engineering toward self-cleaning and color-fastness photonic textiles

Structural coloration using photonic crystals (PCs) has emerged as a significant approach in the textile industry due to their environmental contributions. Cellulose nanocrystals (CNCs), crucial bio-PC with abundant resources and renewability, have shown great potential as photonic dyeing agents. However, due to the high water sensitivity, addressing the anti-washing performance and color fastness becomes important yet challenging. Here, we demonstrate a two-step approach for preparing superhydrophobic and iridescent cotton fabrics (SICFs). By co-assembling CNCs and poly (ethylene glycol) diacrylate under various sonication durations, flexible and tunable chiral nematic nanostructures are constructed on the cotton fabric surfaces. Additionally, surface superhydrophobicity and self-cleaning functions are imparted through the grafting of hyperbranched polyglycidol and 1H, 1H′, 2H, 2H′-perfluorodecyltrichlorosilane. Compared to hydrophilic structural-color counterparts, the resulting SICFs exhibit robust color fastness, surface anti-wettability, and water stability. The molecular design of this work provides new insights to development of eco-friendly textile industry.

Impact of interatomic structural characteristics of aluminosilicate hydrate on the mechanical properties of metakaolin-based geopolymer

This study explores the influence of the interatomic structure of sodium aluminosilicate hydrate (N-A-S-H) with varying silica contents on the mechanical properties of metakaolin-based geopolymer. Geopolymer pastes comprising Si/Al ratios between 2.0 and 3.0 were synthesized. A larger number of Si-O-Si linkages compared to Si-O-Al linkages and a higher atomic number density were found in the geopolymers with higher silica contents, which enhanced the compressive strength of the geopolymer pastes up to the optimal Si/Al ratio of 2.5. The paste with a Si/Al = 2.5 exhibited a greater portion of Q4(1Al and 2Al) and denser morphology compared to the other geopolymer pastes. Furthermore, in-situ high-energy synchrotron X-ray scattering experiments were conducted to assess the elastic modulus of the aluminosilicate structure at a local atomic scale. The modulus value in real space decreases with increasing silica contents up to Si/Al = 2.5 and increases with the presence of excessive unreacted silica fume. The modulus value in reciprocal space for the axial and lateral directions both presented a positive value at the geopolymer comprising a Si/Al ratio higher than 2.5, indicating that the load-bearing property of N-A-S-H changed at higher Si/Al ratios. Moreover, the smallest difference between the strains along the axial and lateral directions was detected for the geopolymer with Si/Al = 2.5 in both the real and reciprocal space, owing to the most interconnected and flexible nanostructure, which led to the highest mechanical strength.

Laser shock forming of metal nanostructures withultrafine gaps.

The nanogaps between metal nanostructures are of great importance in nanotechnology. However, low cost and high precision fabrication of such nanogaps is still a difficult problem. In this paper, a method combining nanosecond laser shock and flexible metal film is proposed to form ultrafine gaps between metal nanostructures. The forming mechanism of ultrafine gaps between metal nanostructures was revealed by studying the superplastic deformation, spatiotemporal evolution of stress and strain, and cooperative deformation of the flexible metal thin film and metal nanostructures under laser shock. On the basis of the mechanism study, the effects of laser parameters and gold nanoparticle size on the forming of ultrafine gaps were further studied, so as to achieve high precision forming of ultrafine gaps (<10n m) between metal nanostructures.

Implantable smart hyperthermia nanofibers for cancer therapy: Challenges and opportunities.

Nanofibers (NFs) with practical drug-loading capacities, high stability, and controllable release have caught the attention of investigators due to their potential applications in on-demand drug delivery devices. Developing novel and efficient multidisciplinary management of locoregional cancer treatment through the design of smart NF-based systems integrated with combined chemotherapy and hyperthermia could provide stronger therapeutic advantages. On the other hand, implanting directly at the tumor area is a remarkable benefit of hyperthermia NF-based drug delivery approaches. Hence, implantable smart hyperthermia NFs might be very hopeful for tumor treatment in the future and provide new avenues for developing highly efficient localized drug delivery systems. Indeed, features of the smart NFs lead to the construction of a reversibly flexible nanostructure that enables hyperthermia and facile switchable release of antitumor agents to eradicate cancer cells. Accordingly, this study covers recent updates on applications of implantable smart hyperthermia NFs regarding their current scope and future outlook. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants.

Lyotropic Liquid Crystal (LLC)-Templated Nanofiltration Membranes by Precisely Administering LLC/Substrate Interfacial Structure

Mesoporous materials based on lyotropic liquid crystal templates with precisely defined and flexible nanostructures offer an alluring solution to the age-old challenge of water scarcity. In contrast, polyamide (PA)-based thin-film composite (TFC) membranes have long been hailed as the state of the art in desalination. They grapple with a common trade-off between permeability and selectivity. However, the tides are turning as these novel materials, with pore sizes ranging from 0.2 to 5 nm, take center stage as highly coveted active layers in TFC membranes. With the ability to regulate water transport and influence the formation of the active layer, the middle porous substrate of TFC membranes becomes an essential player in unlocking their true potential. This review delves deep into the recent advancements in fabricating active layers using lyotropic liquid crystal templates on porous substrates. It meticulously analyzes the retention of the liquid crystal phase structure, explores the membrane fabrication processes, and evaluates the water filtration performance. Additionally, it presents an exhaustive comparison between the effects of substrates on both polyamide and lyotropic liquid crystal template top layer-based TFC membranes, covering crucial aspects such as surface pore structures, hydrophilicity, and heterogeneity. To push the boundaries even further, the review explores a diverse array of promising strategies for surface modification and interlayer introduction, all aimed at achieving an ideal substrate surface design. Moreover, it delves into the realm of cutting-edge techniques for detecting and unraveling the intricate interfacial structures between the lyotropic liquid crystal and the substrate. This review is a passport to unravel the enigmatic world of lyotropic liquid crystal-templated TFC membranes and their transformative role in global water challenges.

Self-assembly of Au nanocrystals into large-area 3-D ordered flexible superlattice nanostructures arrays for ultrasensitive trace multi-hazard detection.

Plasmonic nanoparticles that self-assemble into highly ordered superlattice nanostructures hold substantial promise for facilitating ultra-trace surface-enhanced Raman scattering (SERS) detection. Herein, we propose a boiling-point evaporation method to synthesize ordered monocrystal-like superlattice Au nanostructures (OML-Au NTs) with a polyhedral morphology. Combined with thermal nanoimprint technology, OML-Au NTs were directly transferred to impact-resistant polystyrene (IPS) flexible SERS substrates, the obtained flexible substrates (donated as OML-Au NTs/IPS) detection limit for R6G molecules as low as 10-13 M. These results were confirmed by simulating the electromagnetic field distribution of ordered/unordered two-dimensional single-layer and three-dimensional aggregated gold nanostructures. The OML-Au NTs/IPS substrates were successfully used to detect and quantify three commonly-used agricultural pesticides, achieving detection limits as low as 10-11 M and 10-12 M, and in situ real-time detection limit reached 0.24pg/cm2 for thiram on apple peels, which was 3 orders of magnitude lower than the current detection limit. In addition, the Raman intensity from multiple locations showed a relative standard deviation lower than 7 %, exhibiting the reliability necessary for practical applications. As a result, this research demonstrates a highly reproducible method to enable the development of plasmonic nanomaterials with flexible superstructures.

Layer-by-layer coating of natural diatomite with silver nanoparticles for identification of circulating cancer protein biomarkers using SERS.

Surface-enhanced Raman scattering (SERS) is an emerging spectroscopy technique for detecting and characterizing chemical or biological structures in the vicinity of plasmonic nanostructures. Colloidal, solid, and flexible nanostructures are widely used in SERS experiments to enhance the Raman intensity. The nanostructure used in SERS is one of the main influencing parameters and a growing research area. Fabrication of simple and cheap SERS substrates with a high enhancement factor is desired. In this study, we fabricated a reproducible, cheap, and flexible SERS active strip by coating natural diatomite (biosilica) with silver nanoparticles (AgNPs) using the layer-by-layer assembly method and the fabricated strip is used for the label-free identification of circulating cancer protein biomarkers. SERS active strips were fabricated having different numbers of AgNP layers on natural diatomite and comprehensive characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV/vis absorption spectrophotometry were used. SERS activities of the strips depending on the number of layers were evaluated using 4-aminothiophenol (4-ATP) and rhodamine 6G (Rh6G) molecules. We found that the SERS intensity is strongly dependent on the number of AgNP layers, with the maximum SERS intensity obtained from the strip with 5 layers of AgNPs, having a 2.0 × 105 enhancement factor. The strip with the highest SERS activity was used for the label-free identification of circulating cancer protein biomarkers (HER2, CA15-3, PSA, MUC4, and CA27-29). The results demonstrate that the fabricated strip can help in the effective label-free identification of circulating protein biomarkers and open new directions for SERS-based label-free biosensing applications.

Graphyne-type nano-metamaterials: A comprehensive molecular dynamics simulation

With advances in nanotechnology, the search for novel and nontraditional materials beyond the already known nanostructures such as graphene and graphynes is rising. Recently, a graphyne-like nanostructure with the directional alignment of the acetylenic linkages, the so-called directional graphyne, as an interesting class of nano-metamaterials has been proposed which possesses fascinating physical properties. In this study, the mechanical behavior of the directional graphynes is investigated using molecular dynamics simulation. The effects of temperature, loading direction, and number of acetylenic bonds on the elastic and fracture properties are examined. Comparisons between the mechanical characteristics of the directional graphynes and those of the graphene and graphynes are also provided. The results reveal a high degree of anisotropy in Young's modulus and Poisson's ratio for the directional graphynes compared to the graphene and graphynes. However, the shear modulus is found to be insensitive to the loading direction for all three nanostructures. On the other hand, they all exhibit significant anisotropic fracture properties. An exception is observed for the fracture strain of the directional graphynes under shear loading. The failure mechanisms of the graphynes and directional graphynes are found to be different when the tensile loading is in the zigzag direction. Also, the results indicate that the directional graphynes exhibit interesting and different wrinkle behavior, and especially those with longer acetylenic linkages, are very flexible nanostructures under shear loadings.

Graphene-interfaced flexible and stretchable micro-nano electrodes: from fabrication to sweat glucose detection.

Flexible and stretchable wearable electronic devices have received tremendous attention for their non-invasive and personal health monitoring applications. These devices have been fabricated by integrating flexible substrates and graphene nanostructures for non-invasive detection of physiological risk biomarkers from human bodily fluids, such as sweat, and monitoring of human physical motion tracking parameters. The extraordinary properties of graphene nanostructures in fully integrated wearable devices have enabled improved sensitivity, electronic readouts, signal conditioning and communication, energy harvesting from power sources through electrode design and patterning, and graphene surface modification or treatment. This review explores advances made toward the fabrication of graphene-interfaced wearable sensors, flexible and stretchable conductive graphene electrodes, as well as their potential applications in electrochemical sensors and field-effect-transistors (FETs) with special emphasis on monitoring sweat biomarkers, mainly in glucose-sensing applications. The review emphasizes flexible wearable sweat sensors and provides various approaches thus far employed for the fabrication of graphene-enabled conductive and stretchable micro-nano electrodes, such as photolithography, electron-beam evaporation, laser-induced graphene designing, ink printing, chemical-synthesis and graphene surface modification. It further explores existing graphene-interfaced flexible wearable electronic devices utilized for sweat glucose sensing, and their technological potential for non-invasive health monitoring applications.

Enhanced catalytic oxidation of toluene over heterostructured CeO2-CuO-Mn3O4 hollow nanocomposites

Noble metal-free multicomponent heterostructured nanocomposites are excellent catalysts owing to their flexible compositions, synergistic effects, low cost, and complex nanostructures. Nevertheless, the rational design and synthesis of the multicomponent hollow nanospheres with controllable components, compositions, and structures remains a challenge. We demonstrated that by using carbon nanospheres (CNSs) as templates, a series of hollow ternary CexCu1−xO1+x-Mn3O4 (0 ≤x ≤ 1) nanospheres can be synthesized by a co-precipitation method, followed by the removal of CNSs. The ratio of Ce/Cu in the hollow CexCu1−xO1+x-Mn3O4 nanospheres can be adjusted simply by varying the feeding ratio of Ce and Cu salts. Particularly, hollow Ce0.5Cu0.5O1.5-Mn3O4 catalysts showed excellent catalytic activity and long-term stability, and full conversion of toluene was achieved at 225 °C. Systematic investigation of the catalytic activity and structural information of the ternary CexCu1−xO1+x-Mn3O4 catalysts revealed that the highly dispersed metal oxides, partial formation of solid solutions, and ultrathin hollow structures, all contributed to the catalytic activity. The simplicity and versatility of our approach hold great promise for the preparation of multicomponent heterostructured metal oxides with excellent catalytic activity.

Biomimetic 3D Recognition with 2D Flexible Nanoarchitectures for Ultrasensitive and Visual Extracellular Vesicle Detection.

Despite increasing recognition of extracellular vesicles being important circulating biomarkers in disease diagnosis and prognosis, current strategies for extracellular vesicle detection remain limited due to the compromised sample purification and extensive labeling procedures in complex body fluids. Here, we developed a 2D magnetic platform that greatly improves capture efficiency and readily realizes visible signal conversion for extracellular vesicle detection. The technology, termed high-affinity recognition and visual extracellular vesicle testing (HARVEST), leverages 2D flexible Fe3O4-MoS2 nanostructures to recognize extracellular vesicles through multidentate affinity binding and feasible magnetic separation, thus enhancing the extracellular vesicle capture performance with both yield and separation time, affording high sensitivity with the detection limit of 20 extracellular vesicle particles/μL. Through integration with lipid labeling chemistry and the fluorescence visualization system, the platform enables rapid and visible detection. The number of extracellular vesicles can be feasibly determined by smart mobile phones, readily adapted for point-of-care diagnosis. When clinically evaluated, the strategy accurately differentiates melanoma samples from the normal cohort with an AUC of 0.98, demonstrating the efficient extracellular vesicle detection strategy with 2D flexible platforms for cancer diagnosis.

Ultranarrow Linewidth Coupling Resonance in Flexible Plasmonic Nanopillar Array for Enhanced Biomolecule Detection (Adv. Mater. Interfaces 27/2022)

Plasmonic Nanostructure Sensor In article number 2201011, Shuwen Chu, Yuzhang Liang, and co-workers experimentally demonstrate a flexible plasmonic nanostructure sensor based on a large-scale periodic array of nanopillars. The structure utilizes the coupling of Wood's anomaly and Fabry-Perot modes to generate an ultra-narrow plasmon resonance mode with high sensing figure of merit (FOM), providing an effective strategy for label-free biomolecular sensing with low cost, high sensitivity and high throughput.

Free in-plane bending vibration of flexible L-shaped nanostructures based on the nonlocal beam theory

Free in-plane bending vibration of flexible L-shaped nanostructures based on the nonlocal beam theory

Fabrication and Assessment of Flexible Nanostructured Film for Antibacterial Properties

Fabrication and Assessment of Flexible Nanostructured Film for Antibacterial Properties

Direct Ink Writing of Carbon-Doped Polymeric Composite Ink: A Review on Its Requirements and Applications.

Direct Ink Writing (DIW) opens new possibilities in three-dimensional (3D) printing of carbon-based polymeric ink. This is due to its ability in design flexibility, structural complexity, and environmental sustainability. This area requires exhaustive study because of its wide application in different manufacturing sectors. The present article is related to the variant emerging 3D printing techniques and DIW of carbonaceous materials. Carbon-based materials, extensively used for various applications in 3D printing, possess impressive chemical stability, strength, and flexible nanostructure. Fine printable inks consist predominantly of uniform solutions of carbon materials, such as graphene, graphene oxide (GO), carbon fibers (CFs), carbon nanotubes (CNTs), and solvents. It also contains compatible polymers and suitable additives. This review article elaborately discusses the fundamental requirements of DIW in structuring carbon-doped polymeric inks viz. ink formulation, required ink rheology, extrusion parameters, print fidelity prediction, layer bonding examination, substrate selection, and curing method to achieve fine functional composites. A detailed description of its application in the fields of electronics, medical, and mechanical segments have also been focused in this study.

Formulation, characterization, and optimization of aripiprazole-loaded lyotropic liquid crystalline nanoparticle for sustained release and better encapsulation efficiency against psychosis disorder

Lyotropic liquid crystalline nanoparticles (LLCNPs) have recently received much attention in the application of drug delivery systems, due to their ordered and versatile internal nanostructures that are considered as a key factor in improving loading efficiency of various poorly soluble therapeutic agents. To take advantage on their unique well-defined and flexible internal nanostructures, aripiprazole-loaded LLCNPs consisted of a binary mixture of soy phosphatidylcholine (SPC) and citric acid ester of monoglyceride (citrem) were developed in this study. Despite exhibiting low aqueous solubility which lead to difficulties in formulation, aripiprazole, a class of psychotropic drug called atypical anti-psychotics has been used in the treatment of schizophrenia and bipolar disorder with few side effects. The utmost interest in this study is to explore the potential of LLCNPs in improving the percentage of encapsulation efficiency (EE%) of aripiprazole, their effect on the internal nanostructure of LLCNPs mesophases as well as the drug release performance from LLCNPs. The particle size of drug-loaded LLCNPs produced was in the range of 161–186 nm, with polydispersity index (PDI) between 0.11–0.16, and negative zeta potential of -21.5 to -23.8 mV. Small-angle X-ray scattering (SAXS) measurements indicated that the internal nanostructures of LLCNPs are of inverse hexagonal (H2) with a negligible difference in the lattice parameter before and after drug loading. Transmission electron microscopy (TEM) was used to observe the morphology and overall size distribution of drug-free and drug-loaded nanodispersions, which supported both SAXS and particles size findings. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy demonstrated that aripiprazole interacted physically with binary mixture of citrem/SPC within the nanodispersions. Moreover, the results showed that aripiprazole was successfully encapsulated into LLCNPs nanoparticles, where the EE% was all above 92%. These LLCNPs were not only have a high EE% value, but also exhibited a sustained release performance of aripiprazole with the release capacity of around 97% up to 96 h. From the current study, the potential use of LLCNPs as a promising nanocarrier for aripiprazole delivery is anticipated to improve the pharmacokinetics of this drug whilst enduring the internal nanostructural stability of the LLCNPs upon exposure to physiological environment.

Mechanical characterization of TiO2 nanowires flexible scaffold by nano-indentation/scratch

Mechanical properties of nanowires (NWs) flexible scaffold biomaterials with open pores and channels are important factors to cell reorganize in growth for tissue regeneration engineering. However, accurate test the mechanical properties of the NWs scaffold is still a challenge because of their flexible property and porous structure. Herein, we measured the mechanical characterizes of TiO2 nanowires (TiO2NWs) flexible scaffold by multi-loads, multi-displacements mixed verification method in nano-indentation/scratch. The results showed that the hardness and Young's modulus of the TiO2NWs flexible scaffold had a certain change rules with a change of the indentation load from 5 μN to 400 μN. Meanwhile, the tangential force of the TiO2NWs flexible scaffold had significantly tensile fracture characteristic under nano-scratch. The multi-loads, multi-displacements mixed verification method by nano-indentation/scratch could be widely applied to measure the mechanical properties of all 3D NWs flexible scaffold nanostructure conveniently and accurately, which is helpful to cover the shortage of bending method for only measure the mechanical properties of 1D nanostructures.

Local Cracking‐Induced Scalable Flexible Silicon Nanogaps for Dynamically Tunable Surface Enhanced Raman Scattering Substrates

AbstractSurface enhanced Raman scattering (SERS), as a promising and convenient analytical tool for molecule sensing, has turned out to be one of the most important applications of plasmonic nanostructures. However, its large‐area production, controllability, and adjustability remain significant challenges because of the weak control over the fabrication and spatial arrangement. Herein, a silicon nanogap array‐based flexible plasmonic substrate is developed, with capabilities of large‐area production, controllable arrangement, and width of nanogaps, by utilizing the standard microfabrication platform, and the fabricated flexible plasmonic substrate is further explored for dynamically tunable SERS for molecular sensing. After experimentally and theoretically optimizing the geometric designs of precursors, a 90 × 90 silicon nanogap array (over 1 cm × 1 cm) with a yield of about 99.74% is achieved. SERS is realized by depositing Au films onto the silicon nanogap. Dynamically tunable SERS is demonstrated by the thermally induced local stretch or contraction of silicon nanogaps, where the key parameters including Raman enhancement and sensitivity of the molecular sensor can be conveniently adjusted. These presented results significantly expand the scope of engineering opinions for flexible plasmonic nanostructures, which have many envisioned applications especially for environmental monitoring and biochemical detection.

A review of medicinal plant-based bioactive electrospun nano fibrous wound dressings

In the early time, natural materials were used only to cover the wound but nowadays wound dressings contain functionalize materials to prevent infections, assist wound healing process, and improve skin restoration. Among dissimilar forms of wound dressings, electrospun nanofibrous wound dressings are the latest and promising ones due to their unique properties. These dressings have morphological similarity to the natural extracellular matrix (ECM), high surface area to volume ratio, greater porosity, continuous and flexible nano structure fibers applicable for drug delivery systems which can approve tissue regeneration, wound fliuid transportation and ensure breathability for cellular growth and proliferation. This review provides a broad overview of latest medicinal plant incorporated bioactive electrospun nanofibrous wound dressing researches and developments. It also discussed the therapeutic properties of different traditional medicinal plants.