Applied Materials Today

Journal: Applied Materials Today

Publisher

Elsevier

ISSN

2352-9407

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Publications 1 - 10 of 19

Additive manufacturing of a precious bulk metallic glass
Sohrabi, Navid; Jhabvala, Jamasp; Kurtuldu, Güven; et al. (2021)
Applied Materials Today
For the first time, a high-density amorphous and crack-free bulk metallic glass (BMG) based on a precious metal (PdCuNiP) was produced via additive manufacturing (AM). Laser powder-bed fusion (LPBF) was used for the fabrication of the samples, and led to a density of 99.6%. Excellent mechanical properties such as high hardness and compressive strength were achieved, overcoming the limitations usually found for precious metals in jewelry and watchmaking. Furthermore, without any post-processing, a mirror-like smooth and brilliant surface was directly obtained, which is highly beneficial for applications where surface finish or aesthetics matters. The effect of the main processing parameters, such as laser power and laser-scanning speed, on the shape of single tracks was investigated by laser confocal microscopy (LCM). Following the single-track experiments, highly amorphous LPBF samples were produced. The samples were characterized by optical microscopy (OM), scanning electron microscopy (SEM), conventional and synchrotron X-ray diffraction (XRD), micro-computed tomography (μ-CT), compression tests, and microhardness. The crystallization kinetics of the powder alloy was investigated via fast differential scanning calorimetry (FDSC). A small quantity of the powder (< 70 g) was used for the fabrication of samples, alleviating the cost of the process. Efficient production of precious metal parts with enhanced mechanical properties is demonstrated.
Corrosion mechanisms of magnetic microrobotic platforms in protein media
Rahimi, Ehsan; Offoiach, Ruben; Deng, Siyu; et al. (2021)
Applied Materials Today
The field of biomedical small-scale swimmers has made major progress during the last two decades. While their locomotion aspects and functionalities have been demonstrated, there are key aspects that have been often overlooked such as their service live durability, which difficult their translation to the clinics. Several swimmers consist of combinations of metals and alloys that, while they excel in their functionalities, they fail in their stability due to corrosion in highly aggressive complex body fluids. Here, for the first time the corrosion mechanism of a widely employed design in magnetic microrobots, a gold-coated magnetic NiCo alloy, is assessed. A systematic approach by combining electrochemical and surface analysis techniques is reported, which shed light on the degradation mechanisms of these systems in simulated body fluids. While results demonstrate that Au coatings remarkably enhance the surface nobility and resistance to corrosion/biodegradation of NiCo in an aggressive environment containing albumin protein, Au coatings’ intrinsic defects lead to a galvanic coupling with the NiCo substrate. The coordination of protein with NiCo further accelerates corrosion causing morphological changes to the swimmers’ surface. Yet, the formation of a phosphate-based layer acts as a barrier to the metal release after long immersion periods.
Magnetoelectric 3D scaffolds for enhanced bone cell proliferation
Mushtaq, Fajer; Torlakcik, Harun; Vallmajo-Martin, Queralt; et al. (2019)
Applied Materials Today
Magnetoelectric reduction of chromium(VI) to chromium(III)
Mushtaq, Fajer; Chen, Xiang-Zhong; Veciana, Andrea; et al. (2022)
Applied Materials Today
Toxic heavy-metal pollution represents one of the most pressing environmental challenges that humankind faces today. The conventional approaches for removing highly toxic and carcinogenic heavy metals are currently unsuitable for practical applications. The reduction of harmful heavy metals, such as hexavalent chromium (Cr(VI)) into less harmful trivalent chromium Cr(III), has been gaining considerable interest. In response to this, UV light based photocatalysts have been comprehensively investigated for the reduction of various problematic heavy metals. However, for practical applications, using light as a solution can be highly inefficient owing to poor light absorption in murky or colored heavy metal contaminated water. Here, we demonstrate that wireless magnetic fields can induce the reduction of toxic heavy metals. Core-shell magnetoelectric CoFe2O4@BiFeO3 nano-octahedral particles were fabricated and used for the catalytic reduction of Cr(VI) via the magnetoelectric effect. We have conducted trapping experiments to propose a mechanism behind the magnetoelectric-effect catalytic reduction. We have achieved reduction of 86% of toxic Cr(VI) using a scavenger for singlet oxygen. In addition, we show the concomitant reduction of Cr(VI) and degradation of an organic pollutant, methylene blue, in a synergistic manner, where the presence of methylene blue accelerates the reduction of Cr(VI) to Cr(III).
Polymeric microellipsoids with programmed magnetic anisotropy for controlled rotation using low (≈10 mT) magnetic fields
Bonilla-Brunner, Andrea; Llorente García, Isabel; Jang, Bumjin; et al. (2020)
Applied Materials Today
Drug powders with tunable wettability by atomic and molecular layer deposition: From highly hydrophilic to superhydrophobic
La Zara, Damiano; Zhang, Fuweng; Sun, Feilong; et al. (2021)
Applied Materials Today
The wettability of pharmaceuticals is a key physical property which influences their dissolution rate, dispersibility, flowability and solid-state stability. Here, we provide a platform of surface nanoengineering methods capable of tuning the wettability of drug powders from high hydrophilicity to superhydrophobicity with drug loadings up to 95–99%. Specifically, we functionalize gram-scale micronized budesonide, a commercial active pharmaceutical ingredient for respiratory diseases, in a vibrated fluidized bed reactor with inorganic , and by atomic layer deposition (ALD), organic poly(ethylene terephthalate) (PET) by molecular layer deposition (MLD) and inorganic/organic titanicone by hybrid ALD/MLD. Transmission electron microscopy shows the formation of smooth and uniform films for each deposition process without significantly affecting the surface morphology of the budesonide particles. Crucially, the deposition processes do not alter the solid-state structure and cytocompatibility of budesonide. The ceramic ALD films are able to convert the originally hydrophobic budesonide into highly hydrophilic powders with water contact angles (WCAs) of ~10° within a few seconds. The purely organic PET films grown via MLD deliver superhydrophobic powders with a WCA of 145–150°. In contrast, the titanicone hybrid ALD/MLD films lead to mild hydrophilicity with WCAs ranging from ~80° to ~60°. Modifying the wetting properties of inhaled drug powders such as budesonide is relevant to improve bioavailability, enhance the dispersion of formulations in suspension-based inhalers or prevent moisture interactions in dry powder inhalers. Moreover, by tuning the surface chemical composition at the atomic or molecular level, particle ALD, MLD and hybrid ALD/MLD enable control over powder wettability for several pharmaceutical dosage forms with applications in oral, orally inhaled and parenteral delivery.
Status and future scope of plant-based green hydrogels in biomedical engineering
Mohammadinejad, Reza; Maleki, Hajar; Larrañeta, Eneko; et al. (2019)
Applied Materials Today
DLP 3D – printing of shape memory polymers stabilized by thermoreversible hydrogen bonding interactions
Cosola, Andrea; Sangermano, Marco; Terenziani, Davide; et al. (2021)
Applied Materials Today
In this paper a simple three-components photopolymerizable system based on 2-hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol methyl ether methacrylate) (PEGMEMA) is used for the fabrication of thermoset H-bond stabilized shape memory polymers (SMPs) via digital light processing (DLP) three-dimensional (3D) printing. A bis(acyl)phosphane oxide derivative (BAPO-γ-CyD) was used as an all-in-one photoinitiator and crosslinking agent, so that no conventional multifunctional crosslinkers are needed. Due to the high elasticity ratio between the glassy and rubbery state and the presence of thermoreversibly associating hydrogen-bonding groups, the PHEMA-co-PEGMEMA polymers show an excellent thermally triggered shape memory response (strain recovery of 99%). A prototype of a thermoresponsive airflow diverter has been fabricated, demonstrating the potential integration of such SMPs to develop smart 3D – printed devices. Moreover, the possibility to easily design the glass transition temperature of the SMPs by varying the concentration of the two photopolymerizable ingredients allows to fine-tune the formulations such that materials can be printed showing shape memory behavior at different temperatures.
Silicon oxycarbide-tin nanocomposite derived from a UV crosslinked single source preceramic precursor as high-performance anode materials for Li-ion batteries
Knozowski, Dominik; Sasikumar, Pradeep V.M.; Dubey, Romain; et al. (2022)
Applied Materials Today
In this work, we report an innovative and facile UV light-assisted synthesis of a nanocomposite based on silicon oxycarbide (SiOC) and tin nanoparticles. SiOC ceramic matrix, containing a conductive free carbon phase, participates in lithium-ion storage, and buffers the volume changes of Li-alloying/de-alloying material. The reported synthesis procedure through a polymer-derived ceramic route involves the preparation of a single-source precursor by UV crosslinking of a preceramic polymer in the presence of a tin precursor. Pyrolysis of this starting precursor at 1000 °C leads to a homogenous distribution of tin nanoparticles (25–35 nm) within the SiOC ceramic matrix, which is crucial for electrochemical stability of the material. SiOC/Sn nanocomposite tested as an anode for Li-ion battery exhibits high reversible capacity values (603 mAh g−1 at the current density of 74.4 mA g−1), outstanding rate capability (524 mAh g−1 at 2232 mA g−1), and superior stability (494 mAh g−1 after 250 charge/discharge cycles).
Microenvironment-activatable cascaded responsive carbonized polymer dots as a theranostic platform for precise rapamycin delivery to potentiate the synergy of chemotherapy and γδ T cells-mediated immunotherapy against tumor
Zhang, Hua; Zhao, Haijie; Huang, Yan; et al. (2022)
Applied Materials Today
The combination of chemotherapy and immunotherapy (also known as chemo/immunotherapy) promoted by nanomedicine has the potential to enhance the therapeutic effect in more patient populations. However, it is still affected by the inactivation of immune cells induced by traditional chemotherapy, which greatly impairs the synergistic effect of chemotherapy/immunotherapy substantially. Moreover, once tumor cells lose their MHC expression, the current popular CD8+ T cell-based immunotherapy may fail consequently. Herein, rapamycin, as mTOR signaling inhibitor associated with serious side effect once systemically administered, was incorporated into shell-core theranostic nanoplatform to augment synergy of chemotherapy and γδ T cell-mediated MHC-unrestricted immunotherapy against tumor without toxicity on γδ T cells. This nano-platform assembled from a cleavable shell and a carbonized polymer dot core can achieve accurate delivery of rapamycin with traceable imaging and cascade response. Such cascaded responsiveness has endowed it with improved blood compatibility, effective tumor accumulation, microenvironment-selective endocytosis, and hierarchical drug release facilitated by microenvironment-triggered programmable properties (size shrinkage, charge conversion and degradability) transition responding to blood-tissue-cells multi-level biological barriers. In vitro and in vivo experiments have shown that the nanoplatform not only promotes tumor chemotherapy by down-regulating mTOR signals, but also enhances γδ T cell-mediated immunotherapy by promoting the NKG2D pathway in a microenvironment-selective manner. In addition, the TCR-δ knockout mouse model was used to verify the synergy of chemical/immunotherapy promoted by the nanoplatform. In addition to multifunctional integrated therapeutic and diagnostic strategies, we also provide a paradigm to enhance the synergistic effect of chemotherapy/immunotherapy, and broaden the horizons of immunotherapy through γδ T cell-mediated replacement therapy assisted by nano-drugs.

Publications 1 - 10 of 19

Journal: Applied Materials Today

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