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Well-defined reconstruction parameters are essential to quantify the size, shape, and distribution of nanoscale features in atom probe tomography (APT) datasets. However, the reconstruction parameters of many minerals are difficult to estimate because intrinsic spatial markers, such as crystallographic planes, are not usually present within the datasets themselves. Using transmission and/or scanning electron microscopy imaging of needle-shaped specimens before and after atom probe analysis, we test various approaches to provide best-fit reconstruction parameters for voltage-based APT reconstructions. The results demonstrate that the length measurement of evaporated material, constrained by overlaying pre- and post-analysis images, yields more consistent reconstruction parameters than the measurement of final tip radius. Using this approach, we provide standardized parameters that may be used in APT reconstructions of 11 minerals. The adoption of standardized reconstruction parameters by the geoscience APT community will alleviate potential problems in the measurement of nanoscale features (e.g., clusters and interfaces) caused by the use of inappropriate parameters.
Nowadays, theranostics drug delivery systems (DDSs) with imaging and therapy bi-functions have been regarded as a future orientation for imaging-guided cancer therapy. To achieve high imaging quality, a donor–acceptor (D–A)/Förster resonance energy transfer (FRET) bi-adjustment strategy is carried out for designing dual-colored DDSs with amplified aggregation-induced emission (AIE) behavior for imaging-guided cocktail cancer therapy in this study. In detail, four AIE-active conjugated polymers P-1 to P-4 are synthesized via the Suzuki reaction. Noteworthily, the D–A-type structure is applied in tuning the fluorescence color from orange (P-1) to far-red/near-infrared (P-2), while the intramolecular FRET process further enhanced the fluorescence signal for six times (P-3). Afterwards, P-3-based amphipathic polymer P-4 further acts as a drug carrier in preparing doxorubicin (Dox)- and curcumin (Cur)-loaded polymer dots (Pdots) (Dox-loaded Pdots as PDox and Cur-loaded Pdots as PCur). PDox + PCur DDS is successfully applied in imaging-guided cocktail cancer therapy to give obviously higher in vivo anticancer efficacy compared with single PDox or PCur. In addition, the drug-loaded Pdots also exhibit higher biocompatibility compared with free drugs. This work provides a novel D–A/FRET bi-adjustment strategy for developing high efficiency imaging-guided cocktail DDSs in cancer therapy.
An electrochemical cell was designed to enable in situ atomic force microscopy (AFM) measurements. The finite-element method was implemented using COMSOL Multiphysics to simulate the electrical field within the cell and to find the current and potential distribution. A comparative three-dimensional simulation study was made to compare two different designs and to elucidate the importance of the geometry on the electrical field distribution. The design was optimized to reduce the uncertainty in the measurement of the electrochemical impedance. Then, an in situ, simultaneous electrochemical and time-resolved AFM experiments were conducted to study the surface evolution of the aluminum alloy AA2024-T3 exposed to 0.5 M NaCl. The temporal change of the surface topography was recorded during the application of chrono-amperometric pulses using a newly designed electrochemical cell. Electrochemical impedance spectroscopy was conducted on the sample to confirm the recorded topographical change. The newly developed cell made it possible to monitor the surface change and the growth of the oxyhydroxide layer on the AA2024-T3 with the simultaneous application of electrochemical methods.
Methods that allow for high-throughput synthesis of magnetic nanoparticles are necessary to more feasibly fabricate materials for real-world applications. To accomplish this, in this article, we describe a versatile electrospray-based synthesis method for the synthesis of magnetic cobalt ferrite nanoparticles. This method has the potential to be readily scaled up using methods similar to those currently used in place for the large-scale electrospinning of fibers. To mitigate film formation as often seen with electrospraying ceramics onto a flat plate collector, we developed a method where the magnetic cobalt ferrite nanoparticles were electrosprayed into a silicone oil–based liquid collector. The as-sprayed particles were then crystalized by salt calcining with sodium chloride at 800 °C. The synthesized magnetic nanoparticles obtained using this method had an average particle diameter of 20.7 ± 11.5 nm. This liquid collection method for the synthesis of cobalt ferrite also presents a versatile platform for the synthesis of a wide range of functional nanomaterials and nanocomposites.
Effective cancer therapy is usually limited by the off target distribution of chemotherapeutic drugs and multidrug resistance (MDR) of cancer cells. As a result, the development of a drug delivery system (DDS) capable of targeting cancer cells while at the same time delivering two or more chemotherapeutic drugs is believed to be a good solution to this dilemma. Herein, a hyaluronan-coated meta-organic framework nanoparticles (HM) were fabricated as a DDS in our study to deliver cisplatin (PDD) and oleanolic acid (Ola). Positive results were obtained in our study which reveal that the DDS (HM/PDD/Ola) is favorable in colorectal cancer (HCT116) therapy by enhancing targeted apoptosis and reversing MDR. Compared with applying free drugs or mono DDS, the dual loaded HM/PDD/Ola showed synergistic effects and better performance, which might be a future alternative for the chemotherapy of colorectal cancer.
The field of two-dimensional (2D) materials remains a key area of scientific research today, generating continual interest for electronic, sensing, and quantum technology. As the field progresses beyond proof-of-concept devices, experimental and analytical methods and results must be scrutinized to ensure the veracity of scientific claims. Here, some favored synthesis and characterization techniques within the 2D material (2DM) community and certain limitations inherent to these techniques are discussed. The authors highlight select caveats of solid-source and seed-promoted synthesis techniques, such as difficulties in reproducibility and compromised electrical performance of films synthesized with nucleation agents. Furthermore, the importance of careful characterization methodology in determining 2DM layer number, stoichiometry, and dopant effects is discussed. This article is intended to further educate researchers regarding select techniques and claims in the 2DMs field.
This contribution reports on the biosynthesis of nickel oxide and zinc oxide nanoparticles (NiO-NPs & ZnO-NPs) via a natural extract from Moringa Oleifera leaves as an effective chelating and/or oxidizing/reduction agent of nickel nitrate hexahydrate and zinc nitrate hexahydrate. The structural and optical properties of these two types of semiconductors obtained in a similar procedure are investigated using X-rays Diffraction (XRD), Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR), diffuse reflectance UV-Visible-NIR and Photoluminescence (PL) techniques. The structural analysis shows the formation of pure cubic NiO-NPs and pure wurtzite ZnO-NPs with an average crystallite size of 17.80 nm and 10.81 nm respectively. Their band gaps, calculated from the diffuse reflectance analysis were found to be 4.28 eV and 3.35 eV respectively.
The prepared silver/chitosan nanocomposite and chitosan nanoparticles in this study may demonstrate the potential in optimizing the minimum amount required to achieve complete inactivation of various Coliform bacteria in Nile water. Chitosan nanoparticles were prepared based on the ionic gelation of the prepared chitosan and silver nanoparticles were reduced by Solenostemma Argel extract. Finally, chitosan silver-loaded nanoparticles were prepared by dispersing silver nanoparticles onto the chitosan nanoparticles. The SEM images exhibited a diameter range of 10 nm–30 nm for both of the fabricated silver nanoparticles and chitosan nanoparticles. The UV-Vis analysis confirmed the formation of Ag nanoparticles by the appearance of the characteristic peak at 410 nm. The antibacterial activity of chitosan nanoparticles and silver-loaded nanoparticles was evaluated against the Coliform bacteria. Results show an improvement in the inhibition of the growth of various bacteria tested when silver nanoparticles were introduced which was (0.03g/100ml). Consequently, chitosan silver-loaded nanoparticles could be recommended as an efficient antibacterial material for water disinfection.
RNA delivery into deep tissues with dense extracellular matrix (ECM) has been challenging. For example, cartilage is a major barrier for RNA and drug delivery due to its avascular structure, low cell density and strong negative surface charge. Cartilage ECM is comprised of collagens, proteoglycans, and various other noncollagneous proteins with a spacing of 20nm. Conventional nanoparticles are usually spherical with a diameter larger than 50-60nm (after cargo loading). Therefore, they presented limited success for RNA delivery into cartilage. Here, we developed Janus base nanotubes (JBNTs, self-assembled nanotubes inspired from DNA base pairs) to assemble with small RNAs to form nano-rod delivery vehicles (termed as “Nanopieces”). Nanopieces have a diameter of ∼20nm (smallest delivery vehicles after cargo loading) and a length of ∼100nm. They present a novel breakthrough in ECM penetration due to the reduced size and adjustable characteristics to encourage ECM and intracellular penetration.
In this study, zinc oxide nanoparticles (ZnO NPs) in powder and in thin film were successfully synthesized first time using an eco-friendly, simple and cost effective green synthesis method mediated by corn husk (Zea mays) extract as an effective chelating agent, and zinc nitrate hexahydrate as precursor. Diverse characterizations techniques such as High Resolution – Scanning Electron Microscopy (HR-SEM), Energy Dispersive X- rays Spectroscopy (EDS), X-Rays Diffraction (XRD), and UV – Vis – NIR spectroscopy as well as Photoluminescence (PL) were investigated to confirm ZnO NPs nature. For the ZnO NPs powder, highly crystalline ZnO nanoparticles (ZnO NPs) annealed at 500°C which are 48.635 nm in particles size were characterised by HR-SEM and XRD analysis. The structure morphology and the constituents of the resultant ZnO powder were investigated respectively by HR-SEM and EDS. UV – Visible spectroscopy analysis was investigated on the optical band gap of ZnO NPs, which was calculated to be 3.31 eV. This result indicates that ZnO NPs can be used in metal oxide semiconductor-based devices. For the ZnO NPs thin film, XRD patterns of hexagonal wurtzite structure with c/a ratio about of 1.60 and μ – parameter of 0.38 were obtained. PL measurements showed a broad emission band in the 380 – 800 nm range, centred at 481 nm. ZnO NPs thin film yielded relatively more intense photoluminescence spectra than the ZnO NPs powder. The intrinsic point defects and defect level transitions responsible for the broad emission are discussed.
The advances of iron based magnetic nanoparticles are extensively increasing due to the number of sources related to the synthesis process, the control on the particle dispersion and the interactions of ferrofluids that can be provide with different surface modifications. The wide range of uses granted to them are based on the physical, chemical stability and interaction properties in the different yields of material science. In this work, ferromagnetic iron carbide@iron oxide core@shell nanoparticles were synthesized with hydrophobic nature. Water dispersity was controlled by modifying the surface with a synthesized molecule of oleic acid with ethylenediamine by bioconjugation reaction obtaining a conjugated amide-amine modified oleic acid coating 6 nm magnetic nanoparticles with the capacity of being water dispersable. The synthesized nanoparticles, with modified organic acid and surface modified nanoparticle were characterized by TEM, DLS, zeta potential, mass spectrometry, FTIR and NMR.
In techniques such as Dynamic Light Scattering (DLS), Fluorescence Correlation Spectroscopy, and image mining, motion is tracked by the autocorrelation of a signal over logarithmic time scales. For instance the tracking signal in DLS is the scattered light intensity; it remains correlated at time scales where scant changes in the arrangement of the scattering particles occur, but decays exponentially at the time scales of their diffusion. When there are multiple time scales of motion (for instance due to scatterers of different sizes), the correlation curve has more than one exponential fall. Extracting the decay constants or hydrodynamic sizes due to each exponential fall in a multi-species field correlation curve becomes an ill-conditioned mathematical problem. We describe a new algorithm to invert a multi-modal correlation curve by Sequential Extraction of the Late Exponentials (SELE). The idea is that while the inversion of a multi-exponential equation may be ill posed, that of a single exponential is not. So we fit data windows towards to base of the correlation curve to extract the largest contribution species, remove the species contribution from the correlation curve, and repeat the process with the remnant curve. The single exponent can be robustly fitted by least-square minimization with initial guesses generated by an adapted cumutant technique (power-series) that includes stretch coefficients (measure of sample dispersity). The proposed algorithm resolves particle sizes separated by 3X, and is reliable against fluctuations in the correlation curve and to localized regions of suboptimal data. The algorithm can be used to track particle dynamics in solution in multi-species problems such as self-assembly.
Biosynthesized Zincite nanoparticles have been successfully demonstrated by a completely green process mediated aqueous extract of rosemary leaves acting as both reducing and stabilizing agents and zinc nitrate hexahydrate as the precursor. The synthesis was free of solvents and surfactants to adhere to green chemistry principles and the impartation of environmental benignity. To achieve our objective, structural and optical investigations of ZnO annealed at 500°C for 2hrs were carried-out using complementary techniques. High resolution transmission electron microscopy (HRTEM) revealed the self-assembled, highly agglomerated quasi-hexagonal shaped NPs and the average particle size was found to peak at 15.62 ± 0.22 nm. Selected area electron diffraction (SAED) and X-ray diffraction (XRD) exhibited several diffraction rings with clear diffraction spots confirming their polycrystallinity and the purity of ZnO NPs with a wurtzite structure. Furthermore, the energy dispersive X-ray spectroscopy (EDS) substantiated the presence of Zn and O in the sample and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) illustrated the Zn-O chemical bonds. From UV-Vis-NIR, the optical band gap was amounted to 3.2 eV and photoluminescence (PL) emission spectrum to 2.9eV with high surface defects and oxygen vacancies. Through these results, the use of rosemary leaves extract is hereby shown to be a cost-effective and environmentally friendly alternative to synthesize Zincite nanoparticles (ZnO NPs).
Silver nanoparticles (Ag NPs) have unique optical, electrical, and thermal properties and are being incorporated into products that range from photovoltaics to biological and chemical sensors. The production of silver nanoparticles has been increasing worldwide in the nanotechnology industry due to the variety of applications and are very likely to reach aquatic ecosystems damaging them. Due to their small size and high surface area to volume ratio of NPs, they can strongly interact with life cells and cause damage to tested animals. Based on the mentioned previously, it is necessary to evaluate the silver nanoparticle nanotoxicity in aquatic ecosystems to prevent possible ingestion or transfer to humans. Also, the research will benefit aquatic systems due to less pollution around aquatic organisms. The objectives of this research included: i) production and characterization of stable silver nanoparticles in water, ii) characterizing the optical properties by UV-Vis spectroscopy and morphology by HR-TEM and; iii) evaluate the toxicity of silver nanoparticles in aquatic organisms, i.e Artemia salina. Results obtained evidenced that Ag NPs showed an intense absorption peak at 448 nm. This broad peak is due to the phenomenon called surface plasmon resonance (SPR) that is responsible for a variety of phenomena, including nanoscale optical focusing, negative refraction, and surface-enhanced Raman scattering. HR-TEM measurements evidenced the spherical form of the nanoparticles and its small size at around 12-20 nm. In addition, Electron Diffraction analyses suggested the composition of the nanoparticle, which contained only Ag0. The toxicity assays were evaluated using different concentrations of purified Ag NPs. During the cytotoxicity assay, it was demonstrated that Ag NPs were not toxic to Artemia salina after 24 and 48 hours of exposure. However, silver (as silver nitrate) evidenced high toxicity to Artemia salina at larval stage.
Boron nitride nanotubes (BNNTs) and hexagonal boron nitride platelets (h-BNs) have received considerable attention for aerospace insulation applications due to their exceptional chemical and thermal stability. Presently, making BN nanomaterials compatible with polymer and composite matrices is challenging. Due to their inert and highly stable structure, h-BN and BNNTs are difficult to covalently functionalize. In this work, we present a novel sonochemical technique that enables covalent attachment of fluoroalkoxy substituents to the surface of BN nanomaterials in a controlled and metered process. Covalent functionalization is confirmed via colloidal stability analysis, FT-IR, and x-ray photoelectron spectroscopy (XPS).
Machine learning-based approach is desired for accelerating materials design, development and discovery in combination with high-throughput experiments and simulation. In this work, we propose to apply a Bayesian optimization method to design ultrathin multilayer tungsten-silicon carbide (W-SiC) nanocomposite absorber for high-temperature solar power generation. Based on a semi-analytical scattering matrix method, the design of spectrally selective absorber is optimized over a variety of layer thicknesses to maximize the overall solar absorptance. Our nanofabrication and experimental characterization results demonstrate the capability of the proposed approach for accelerated development of refractory light-absorbing materials. Comparison with other global optimization methods, such as random search, simulated annealing and particle swarm optimization, shows that the Bayesian optimization method can expedite the design of multilayer nanocomposite absorbers and significantly reduce the development cost. This work sheds light on the discovery of novel materials for solar energy and sustainability applications.
Multifunctional nanoparticles are an emerging area of research, impacting numerous fields ranging from biomedical applications to energy. While initial core–shell structures consisted of similar materials, such as Au–Ag or CdTe–CdSe nanoparticles, recent work has expanded this line of investigation to include particles of dissimilar materials. However, there are several challenges when synthesizing dissimilar material systems. In this work, a method for doping the shell of an Au–ZnO nanosphere is demonstrated. Several metal dopants are investigated, including Cu, Ce, Er, Nd, Tm, and Yb. The ZnO shell is nucleated on the gold nanosphere core via an ascorbic acid–assisted growth, and the dopant is intercalated uniformly into the shell during the self-assembly phase of the shell formation. The doping and polycrystalline shell are confirmed using a series of qualitative and quantitative methods. This multi-material nanoparticle synthesis strategy opens the door for future applications in sensing, photocatalysis, and bioimaging.
Flexural and thermomechanical properties of the epoxy-based carbon fiber composites (CFCs) on addition of single and binary nanoparticles (nanoclay and graphene) have been investigated. It was found that nanoclay acts more effectively in increasing the stiffness of the CFCs, whereas graphene is more effective in achieving higher strength. Nanoclay-added samples exhibited highest flexural (64.5 GPa) and storage (25.3 GPa) modulus among all types. Graphene-added samples showed highest improvement (by 21%) in flexural strength and exhibited most stable thermomechanical properties with highest energy dissipation capability (3.1 GPa loss modulus) in flexural test and dynamic mechanical analysis (DMA), respectively. By contrast, addition of binary nanoparticles reduced the stiffness and significantly increased the strain to failure (42%) of the composites. Optical microscopy and scanning electron microscopy indicated that addition of nanoparticles significantly reduced delamination and matrix cracking of the CFCs because of strong interfacial bonding and toughened matrix, respectively.
Nano-forms of copper oxides (CuO and Cu2O) are potential candidates in the field of energy conversion and storage. Low temperature and controlled growth of three-dimensional nanostructured hierarchical assembly of CuO over Cu2O is reported here with demonstrated advantage in energy conversion and storage applications. Electrodeposited Cu2O is partially oxidized in an alkali bath to two different forms of hierarchical nanostructures (HNS): CuO/Cu2O and CuO:Cu(OH)2/Cu2O. Randomly oriented nanorods and nanoflakes with high surface area tussock-like nanostructure are formed during oxidation at room and at elevated temperatures, respectively. The nanoflake morphology exhibits a high surface area of 85.82 m2/g and sufficient ion percolation pathways, leading to an efficient electrode–electrolyte interface for electrochemical energy devices. A favorable conduction and valence band alignment in the HNS with respect to water redox level along with fast electron diffusion time of 0.8 μs make it an ideal photocathode.
Conventional silicon-based electronics have faced challenges in the realization of soft bioelectronics, such as wearable and implantable integrated devices, which necessitate electrically and mechanically interactive biotic–abiotic interfacing without disturbing the daily life of the user or posing biocompatibility issues. Recently, much effort has been directed at overcoming the mechanical limitations of conventional rigid electronics by replacement of bulky, thick, and rigid electronic materials with biocompatible, soft, and nanoscale electronic materials, which exhibit intrinsic mechanical deformability as well as superior electrical properties. Recent advances in the synthesis of unconventional nanomaterials, surface functionalization methods, and integrated device fabrication techniques have resulted in further improvements in the performance of nanomaterials-based soft bioelectronics. Numerous studies have focused on the biological, electrical, and mechanical analyses of heterogeneous nanomaterial–biosystem interfaces as well as the development of efficient integration processes of soft nanomaterials into devices. In this article, we summarize the latest advances and future prospects in nanomaterials synthesis, processing, and integration strategies for flexible and stretchable bioelectronics, and their application to wearable and implantable devices.