Formation Of Nanostructures Research Articles

Synergistic effect of ZnO Thin Films with Gold as Antifungal Coatings

Microbial contamination on surfaces is a problem worldwide, affecting public health and industry. The increasing prevalence and severity of microbial infection outbreaks across various environments have highlighted the urgent need to develop antimicrobial coatings/surfaces to mitigate the risk of disease transmission through high‐touched surfaces. This work focuses on assessing the antifungal activity of thin films based on zinc oxide (ZnO), produced by reactive magnetron sputtering with varying thicknesses, and evaluating the impact of varying gold concentrations within the ZnO matrix on both microstructure and antifungal activity. The developed thin films exhibit noteworthy antifungal activity against the fungus Candida albicans, achieving 80% reduction in cell viability, regardless of thickness and gold concentration (up to 15.4 at%). Annealing treatment at 600 °C induces the formation of large and irregular gold nanostructures (sizes from 39 to 260 nm), enhancing the antifungal activity compared to the as‐deposited samples. This highlights the surface‐dependent antifungal efficacy of ZnO‐based thin films and a synergistic effect when combined with gold. Additionally, the thin films not only exhibit antifungal activity but also demonstrate potential for localized surface plasmon resonance applications. Overall, ZnO‐based thin films hold promise as antifungal coatings for diverse surfaces, offering a preventive measure against microbial contamination.

Nanopatterning and nanostructure formation with femtosecond laser: Revolutionizing surface engineering on soda-lime glass

Glass, due to its high transparency and chemical stability, has found extensive use in electrical, electronic, and optoelectronic devices. This study presents a novel approach to modify the morphological features of laser-generated tracks and produced nanoparticles in soda-lime glass using the accuracy of micro processing by femtosecond laser pulses. The investigation has meticulously examined how variations in the incident laser pulse energy and scanning velocity dictate the formation of distinct morphological characteristics on the glass surface. FESEM has revealed three distinct morphological formations, including particulate, self-ordered periodic surface structures, and a combination of the two. Additionally, TEM analysis has shown the generation of both spherical and irregular-shaped nanoparticles with diameters ranging from 10 nm to less than 2 μm, and an amorphous structure confirmed by SAED patterns. The periodicity of the LIPSS was found to be 550±25 nm, and they were oriented perpendicular to the laser polarization vector.

Investigation of the Strain–Stress Field in Nanoscale Multilayer Systems by the Phase Plane Method

This paper presents the results of the study of stress relaxation fields, deformation, and temperature of the system of nanostructured multilayer coatings. In the work, a nonlinear relationship between strain and stress was used to take into account nonlinear effects in the mechanism of nanostructure formation. The paper assumes that a friction surface is provided by the self-organization of shear components: both stress and strain on the one hand, and temperature on the other. The studied objects are described in the adiabatic approximation, taking into account the fact of the evolution of stresses and strains. With the help of phase portraits of the system, the dependence of the deformation processes on the stresses arising in the system without coating and with coating is shown. It is shown that the rate of change of deformation depends on the characteristics of the mechanical impact on the coating and on the amount of stress and deformation. A conclusion is drawn regarding the transition process in the presence of two regions (Hooke and plastic deformation) in the corresponding phase portrait of the strain–stress field of the system. The results of the work can be used to determine the effective parameters of a coating in the analysis of experimental time dependences of stresses.

Thermal and electric field driven rf breakdown precursor formation on metal surfaces

The phenomenon of electric breakdown poses serious challenges to the design of devices that operate in high electric field environments. Experimental evidence points toward breakdown events that are accompanied by elevated temperatures and dark current spikes, which is attributed to high-asperity nanostructure formation that enhances the local electric field and triggers a runaway process. However, the exact mechanistic origin of such nanostructures under typical macroscopic operational conditions of electric field and magnetic-field-mediated heating remains poorly understood. In this work, we simulate the evolution of a copper surface under the combined action of the electric fields and elevated temperatures. Using a mesoscale curvature-driven surface evolution model, we show how a copper surface can undergo a type of dynamical instability that naturally leads to the formation of sharp asperities in realistic experimental conditions. Exploring the combined effect of fields and temperature rise, we identify the critical regimes that allow for the formation of breakdown precursors. The results show that thermoelastic stresses, while not essential, can significantly lower the critical electric field required for runaway surface instability, which is consistent with experimental observations that thermal effects can increase breakdown rates. Published by the American Physical Society 2024

Phytochemical Profiling of Phragmites australis Leaf Extract and Its Nano-Structural Antioxidant, Antimicrobial, and Anticancer Activities

AbstractFreshwater macrophytes have attracted interest as an alternative source of natural extracts and minerals for a variety of therapeutic uses. However, few studies have rigorously investigated the phytochemical components, properties, and potential biological benefits of Phragmites australis as an emergent macrophyte. This study investigates the phytochemical profile of aqueous Phragmites australis (PAE) leaves extract using chromatographic-mass spectrometry and free radical scavenging analysis. LC-QToF-MS/MS analysis in both positive and negative ionization revealed the existence of thirty and eleven bioactive compounds, respectively tentatively identified as alkaloids, flavonoids, indoles, glycosides, and quinolines from the extract. The polyphenolic content of the PAE was found to be 39.17 ± 0.65 mg GAE/g total phenol, while the flavonoids content was 19.85 ± 2.64 mg QE/g, and proanthocyanins content was 119.65 ± 1.70 CE/g. The PAE was utilized to synthesize silver nanoparticles (AgNPs) to evaluate its nano-structural formation efficiency, with the PAE displaying a greater ability to scavenge free radicals against ABTS, DPPH, and FRAP when compared with PA-AgNPs. Both PAE and PA-AgNPs were tested for their antimicrobial and anticancer activities and the results indicated that PA-AgNPs (MIC value range of 7.8–62.5 µg/mL) had excellent antimicrobial activity, compared to PAE. Moreover, the antiproliferative effect of PA-AgNPs on human cancer cells showed a higher cell-specific dose response and two-fold apoptotic induction with increased phosphorylation in the DNA ss-strand break post-treatment in MCF-7 than in A549 cells. These findings reveal the potential of the leaf extract of PA as a potent antioxidant source for many biological applications.

Carbon nanostructures synthesis by catalyst-free atmospheric pressure plasma jet

In this study, carbon nanostructures were synthesized utilizing a warm plasma jet at atmospheric pressure in a continuous and catalyst-free process. The procedure and apparatus were designed and constructed in our laboratory. Plasma was generated with 600 W of electrical energy, using a high-voltage, high-frequency alternating current power source. The working gas utilized was a propane/butane mixture, with a concentration ratio of 60:40, respectively. A production rate of 300 mg min−1 of powdered material was achieved, with a particle size between 20 and 100 nm. The product was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, Raman spectroscopy, x-ray diffraction, and transmission electron microscopy. Results show the formation of multilayer carbon nanostructures with a low content of functional groups; the obtained material presented structural defects and amorphous carbon. This work demonstrates that, with adequate control, warm plasma jet discharges can be employed for the synthesis of carbon nanostructures. The process is scalable and can be utilized for hydrocarbon reforming and hydrogen production. However, further studies are needed to improve the quality of the nanostructures and process efficiency. The synthesized material can potentially be used in gas adsorption or in the manufacture of polymeric nanocomposites with enhanced thermal, electrical, and mechanical properties.

Nanostructured High Entropy Alloys as Structural and Functional Materials.

Since their introduction in 2004, high entropy alloys (HEAs) have attracted significant attention due to their exceptional mechanical and functional properties. Advances in our understanding of atomic-scale ordering and phase formation in HEAs have facilitated the development of fabrication techniques for synthesizing nanostructured HEAs. These materials hold immense potential for applications in various fields including automobile industries, aerospace engineering, microelectronics, and clean energy, where they serve as either structural or functional materials. In this comprehensive Review, we conduct an in-depth analysis of the mechanical and functional properties of nanostructured HEAs, with a particular emphasis on the roles of different nanostructures in modulating these properties. To begin, we explore the intrinsic and extrinsic factors that influence the formation and stability of nanostructures in HEAs. Subsequently, we delve into an examination of the mechanical and electrocatalytic properties exhibited by bulk or three-dimensional (3D) nanostructured HEAs, as well as nanosized HEAs in the form of zero-dimensional (0D) nanoparticles, one-dimensional (1D) nanowires, or two-dimensional (2D) nanosheets. Finally, we present an outlook on the current research landscape, highlighting the challenges and opportunities associated with nanostructure design and the understanding of structure-property relationships in nanostructured HEAs.

Advancements in Aptamer-Driven DNA Nanostructures for Precision Drug Delivery.

DNA nanostructures exhibit versatile geometries and possess sophisticated capabilities not found in other nanomaterials. They serve as customizable nanoplatforms for orchestrating the spatial arrangement of molecular components, such as biomolecules, antibodies, or synthetic nanomaterials. This is achieved by incorporating oligonucleotides into the design of the nanostructure. In the realm of drug delivery to cancer cells, there is a growing interest in active targeting assays to enhance efficacy and selectivity. The active targeting approach involves a "key-lock" mechanism where the carrier, through its ligand, recognizes specific receptors on tumor cells, facilitating the release of drugs. Various DNA nanostructures, including DNA origami, Tetrahedral, nanoflower, cruciform, nanostar, nanocentipede, and nanococklebur, can traverse the lipid layer of the cell membrane, allowing cargo delivery to the nucleus. Aptamers, easily formed in vitro, are recognized for their targeted delivery capabilities due to their high selectivity for specific targets and low immunogenicity. This review provides a comprehensive overview of recent advancements in the formation and modification of aptamer-modified DNA nanostructures within drug delivery systems.

Phase-controllable synthesis of nickel selenide nanostructures decorated on carbon nanotubes as efficient binder-free cathodes for hybrid supercapacitors

In this work, we employed a facile pulse-reversal (PR) electrodeposition route to successfully synthesize nickel selenide nanostructures directly decorated on carbon nanotubes (CNTs) by adjusting different pulse-reversal potentials. The study systematically investigated the effects of PR potential on the morphology and composition of nickel selenides on CNTs. The experimental results suggested that regulating the PR potential could effectively manage the formation of nickel selenide nanostructures on the backbones of CNTs. By decreasing the PR potential from 0.2 to −0.2 V, the composition of nickel selenide nanostructures changed from NiSe2 to Ni0.85Se. The CNTs@NiSe2 electrode outperformed the others with a specific capacity of 125.4 mAh g−1 at 2 A g−1 and an impressive capacity retention of 81.2 % at 16 A g−1. The assembled hybrid supercapacitor using CNTs@NiSe2 as the cathode achieved exceptional performance with a high specific capacity of 42 mAh g−1 at 1 A g−1 and a maximum energy density of 33.6 Wh kg−1 at 800 W kg−1. This work presents an efficient approach that can be widely employed to fabricate one-dimensional carbon material-supported transition metal selenide nanostructures for practical applications in the next generation of energy storage and conversion.

Study of Nanostructured Layer Growth on Plasma-Facing Materials Irradiated with Helium Plasma

Tungsten and stainless steel samples were irradiated with stationary helium plasma in the plasma linear multicusp plasma device. The surface of the material is modified under the influence of helium plasma with the formation of nanostructures and microstructures on the surface. The fluence of helium ions equal to 8 × 1027 ions/m2 was achieved on the tungsten sample. Depending on the helium ion fluence, fuzzlike layers, loops, and bubbles of 20- to 500-nm scale were formed on the tungsten surface. The fuzz layer thickness depends on the duration of plasma irradiation in a wide range of fluence. Saturation of the growth of the thickness of the tungsten fuzz layer was observed at a fluence of more than 8 × 1026 ions/m2. The growth of microstructures and nanostructures on the surface of stainless steel irradiated with helium plasma was observed. The growth of nanostructured layers is explained by a theoretical model considering the dynamics of adatoms under the influence of plasma.

Cellulose-based aerogel derived N, B-co-doped porous biochar for high-performance CO2 capture and supercapacitor

The remarkable characteristics of porous biochar have generated significant interest in various fields, such as CO2 capture and supercapacitors. The modification of aerogel-derived porous biochar through activation and heteroatomic doping can effectively enhance CO2 adsorption and improve supercapacitor performance. In this study, a novel N, B-co-doped porous biochar (NBCPB) was synthesized by carbonating and activating the N, B dual-doped cellulose aerogel. N and B atoms were doped in-situ using a modified alkali-urea method. The potassium citrate was served as both an activator and a salt template to facilitate the formation of a well-developed nanostructure. The optimized NBCPB-650-1 (where 650 corresponded to activation temperature and 1 represented mass ratio of potassium citrate activator to carbonized NBCPB-400 precursor) displayed the largest micropore volume of 0.40 cm3·g−1 and a high specific surface area of 891 m2·g−1, which contributed to an excellent CO2 adsorption capacity of 4.19 mmol·g−1 at 100 kPa and 25 °C, a high CO2/N2 selectivity, and exceptional reusability (retained >97.5 % after 10 adsorption-desorption cycles). Additionally, the NBCPB-650-1 electrode also delivered a high capacitance of 220.9 F·g−1 at 1 A·g−1. Notably, the symmetrical NBCPB-650-1 supercapacitor exhibited a high energy density of 9 Wh·kg−1 at the power density of 100 W·kg−1. This study not only presents the potential application of NBCPB-650-1 material in CO2 capture and electrochemical energy storage, but also offers a new insight into easy-to-scale production of heteroatomic-modified porous biochar.

Multi-sensor-based process monitoring and quality assessment during laser forming of novel titanium foam to prevent cellular structure damage

Titanium foam finds its application in different fields like battery electrodes, heat exchangers, biological prosthetics, and lightweight structures for aeronautical parts. However, the inherent property of the foam to fail during mechanical loading conditions poses a challenge in providing final shape to these materials for practical applications. The present work investigates forming of Titanium foam (Ti Foam) using inline process monitoring for achieving controlled foam deformation while maintaining its quality without failure. Infrared (IR) pyrometer and laser-based displacement sensor were used to monitor the foam deformation behavior and thermal signature. The monitoring data were used to understand the process mechanism of laser forming. The bending mechanism within the foam was analysed with respect to solid sheet bending process. The correlation of the achieved bending angles, was attempted with the process parameters for surface, microstructural, elemental, and phase transformation. A critical analysis of Ti foam behavior, like surface melting, in situ oxidation, phase transformation, and formation of nano-structures on foam surface was addressed based on process parameter combinations. Micro-computed tomography (μCT) was carried out to investigate the pore deformation mechanism. Metallurgical characterisations for foam surface and phase analysis were carried out using X-ray photoelectron spectroscopy (XPS) and tunneling electron microscopy (TEM) to determine the chemical and crystallographic states of the laser-formed surface.

Investigating the influence of pore-widening time control in electrochemical anodization for the formation of hybrid titanium nanostructures with enhanced superhydrophobicity for improved corrosion resistance efficiency

Titanium (Ti) alloys possess remarkable strength, high-temperature stability, and processability, making them indispensable in biomaterials, aircraft engines, fuselage manufacturing, and ship propulsion shafts. However, when exposed to potential differences or minor defects in contact with other alloys, the thin natural oxide film on their surface is vulnerable to damage, leading to accelerated corrosion or diminished stability. This study investigated the morphology of the final oxide film formed with varying pore-widening (PW) process time (10–60 min with 10-minute intervals) after the anodization of Ti-Grade 4 material. The oxide films formed from the anodization and the PW process for 10 to 40 min exhibited a porous structure, while a hybrid pillar and pore structure were observed after a PW process of 50 min. As the PW time increases, the pore diameter expands, forming hybrid pillar and pore nanostructures, and superhydrophilicity is observed. After FDTS (1H, 1H, 2H, 2H-Perfluorooctyltrichlorosilane) coating, the phenomenon elucidates the transition from hydrophobicity to superhydrophobicity and the enhancement of water droplet mobility, with the lowest contact angle hysteresis measured at PW of 60 min and demonstrating improved corrosion resistance, achieving a corrosion inhibition efficiency of over 99% compared to the untreated titanium alloy surface. Notably, the structure encompassing pillar and pore features exhibits exceptional suitability for applications on material surfaces and interfacial phenomena, such as cell adhesion. Furthermore, surfaces characterized by excellent superhydrophobicity because of coating can find multifunctional applications encompassing anti-corrosion, anti-fouling, anti-icing, and self-cleaning capabilities.

A Ligand-Directed Spatial Regulation to Structural and Functional Tunability in Aggregation-Induced Emission Luminogen-Functionalized Organic-Inorganic Nanoassemblies.

Aggregation-induced emission luminogen (AIEgen)-functionalized organic-inorganic hybrid nanoparticles (OINPs) are an emerging category of multifunctional nanomaterials with vast potential applications. The spatial arrangement and positioning of AIEgens and inorganic compounds in AIEgen-functionalized OINPs determine the structures, properties, and functionalities of the self-assembled nanomaterials. In this work, a facile and general emulsion self-assembly tactic for synthesizing well-defined AIEgen-functionalized OINPs is proposed by coassembling alkane chain-functionalized inorganic nanoparticles with hydrophobic organic AIEgens. As a proof of concept, the self-assembly and structural evolution of plasmonic-fluorescent hybrid nanoparticles (PFNPs) from concentric circle to core shell and then to Janus structures is demonstrated by using alkane chain-modified AuNPs and AIEgens as building blocks. The spatial position of AuNPs in the signal nanocomposite is controlled by varying the alkane ligand length and density on the AuNP surface. The mechanism behind the formation of various PFNP nanostructures is also elucidated through experiments and theoretical simulation. The obtained PFNPs with diverse structures exhibit spatially tunable optical and photothermal properties for advanced applications in multicolor and multimode immunolabeling and photothermal sterilization. This work presents an innovative synthetic approach of constructing AIEgen-functionalized OINPs with diverse structures, compositions, and functionalities, thereby championing the progressive development of these OINPs.

Electrocatalytic properties of Ni–Cu structures fabricated by electrodeposition of Cu on Ni cones

Ni–Cu alloys are a suitable candidate as a catalyst in Hydrogen Evolution Reaction due to their catalytic performance and good stability. To enhance this activity more, the active surface area of the material should be enhanced. It is commonly achieved by the synthesis of metals and alloys in the form of nanostructures. In this work, Ni cones fabricated by the one-step method were applied as a substrate for the deposition of thin Cu layers. Then, these materials were annealed in an ambient atmosphere to obtain Ni–Cu structures. The investigation of changes in morphology and chemical composition, as well as roughness and wettability before and after the annealing process was performed. Moreover, the measurements of catalytic properties were carried out in 1 M NaOH. The values of the Tafel slope and the electrochemical active surface area were studied. The proposed method can be successfully applied to fabricate structures of other alloys for the desired properties.

The effects of histidine substitution of aromatic residues on the amyloidogenic properties of the fragment 264–277 of nucleophosmin 1

Histidine (His) plays a key role in mediating protein interactions and its unique side chain determines pH responsive self-assembling processes and thus in the formation of nanostructures. In this study, To identify novel self-assembling bioinspired sequences, we analyzed a series of peptide sequences obtained through the point mutation of aromatic residues of 264–277 fragment of nucleophosmin 1 (NPM1) with single and double histidines. Through several orthogonal biophysical techniques and under different pH and ionic strength conditions we evaluated the effects of these substitutions in the amyloidogenic features of derived peptides. The results clearly indicate that both the type of aromatic mutated residue and its position can have different effect on amyloid-like behaviors. They corroborate the crucial role exerted by Tyr271 in the self-assembling process of CTD of NPM1 in AML mutated form and add novel insights in the accurate investigation of how side chain orientations can determine successful design of innovative bioinspired materials.

Lysosomal Peptide Self-Assembly To Control Cell Behavior.

Lysosomes are membrane-enclosed organelles that play key roles in degrading and recycling cellular debris, cellular signaling, and energy metabolism processes. Confinement of amphiphilic peptides in the lysosome to construct functional nanostructures through noncovalent interactions is an emerging approach to tune the homeostasis of lysosome. After briefly introducing the importance of lysosome and its functions, we discuss the advantages of lysosomal nanostructure formation for disease therapy. We next discuss the strategy for triggering the self-assembly of peptides in the lysosome, followed by a concise outlook of the future perspective about this emerging research direction.

Nanostructured boron-doped diamond electrodes for two-electron water oxidation to produce hydrogen peroxide

Boron-doped diamond (BDD) electrodes have been widely used in water treatment, e.g., degradation of antibiotics and pigments for water purification. Hydrogen peroxide production by two-electron electrochemical oxidation of water is a green and attractive method that has the potential to replace the conventional anthraquinone autoxidation (AO) process. In this study, BDD films were prepared on single-crystal silicon wafers by using hot-filament chemical vapor deposition (HFCVD) technique. Then, dense tubular nanostructure (nanotubes) arrays were prepared on the BDD films employing inductively coupled plasma (ICP) etching. Energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) proved the formation of oxygen-terminated nanostructures, which was ascribed to the oxygen plasma and the self-masking. The length of diamond nanotubes as well as the root diameter increased gradually and non-linearly with the increase of etching time. It was indicated by cyclic voltammetry (CV) analysis that the effective active area of the electrodes increased after etching, and variations of resulting reaction performance were observed. The oxygen-terminated and nanostructured BDD electrode obtained by etching with the optimized parameters features better electrocatalytic performance, with reduced oxidation potential and 46.8 % higher Faraday Efficiency (FE) for hydrogen peroxide production, compared to the original BDD sample. Therefore, the manufacturing of nanostructures is an effective method to improve the efficiency of BDD water oxidation for the production of hydrogen peroxide.

One-pot Formulation of Cationic Oligochitosan Coated Nanoparticles via Photo- Polymerization Induced Self-Assembly.

During last few decades, oligochitosan (OCS)-coated nanoparticles have received great interest for nanomedicine, food and environment applications. However, their current formulation techniques are time-consuming with multi-synthesis/purification steps and sometimes require the use of organic solvents, crosslinkers and surfactants. Herein, we report a facile and rapid one-pot synthesis of OCS-based nanoparticles using photo-initiated reversible addition fragmentation chain transfer polymerization-induced self-assembly (Photo-RAFT PISA) under UV-irradiation at room temperature. To achieve this, OCS was first functionalized by a chain transfer agent (CTA) resulting in a macromolecular chain transfer agent (OCS-CTA), which will act as a reactive electrostatic/steric stabilizer. Owing to its UV-sensitivity, OCS-CTA was then used as photo-iniferter to initiate the polymerization of 2-hydroxypropyl methacrylate (HPMA) in aqueous acidic buffer, resulting in OCS-g-PHPMA amphiphilic grafted copolymers which self-assemble into nano-objects. Transmission electron microscopy and light scattering analysis reveal formation of spherical nanostructures.

Developing Isomeric Peptides for Mimicking the Sequence-Activity Landscapes of Enzyme Evolution.

Enzymes catalyze almost all material conversion processes within living organisms, yet their natural evolution remains unobserved. Short peptides, derived from proteins and featuring active sites, have emerged as promising building blocks for constructing bioactive supramolecular materials that mimic native proteins through self-assembly. Herein, we employ histidine-containing isomeric tetrapeptides KHFF, HKFF, KFHF, HFKF, FKHF, and FHKF to craft supramolecular self-assemblies, aiming to explore the sequence-activity landscapes of enzyme evolution. Our investigations reveal the profound impact of peptide sequence variations on both assembly behavior and catalytic activity as hydrolytic simulation enzymes. During self-assembly, a delicate balance of multiple intermolecular interactions, particularly hydrogen bonding and aromatic-aromatic interactions, influences nanostructure formation, yielding various morphologies (e.g., nanofibers, nanospheres, and nanodiscs). Furthermore, the analysis of the structure-activity relationship demonstrates a strong correlation between the distribution of the His active site on the nanostructures and the formation of the catalytic microenvironment. This investigation of the sequence-structure-activity paradigm reflects how natural enzymes enhance catalytic activity by adjusting the primary structure during evolution, promoting fundamental research related to enzyme evolutionary processes.