| 1. |
- Afewerki, Samson, et al.
(författare)
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Combined Catalysis : A Powerful Strategy for Engineering Multifunctional Sustainable Lignin-Based Materials
- 2023
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 17:8, s. 7093-7108
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Tidskriftsartikel (refereegranskat)abstract
- The production and engineering of sustainable materials through green chemistry will have a major role in our mission of transitioning to a more sustainable society. Here, combined catalysis, which is the integration of two or more catalytic cycles or activation modes, provides innovative chemical reactions and material properties efficiently, whereas the single catalytic cycle or activation mode alone fails in promoting a successful reaction. Polyphenolic lignin with its distinctive structural functions acts as an important template to create materials with versatile properties, such as being tough, antimicrobial, self-healing, adhesive, and environmentally adaptable. Sustainable lignin-based materials are generated by merging the catalytic cycle of the quinone-catechol redox reaction with free radical polymerization or oxidative decarboxylation reaction, which explores a wide range of metallic nanoparticles and metal ions as the catalysts. In this review, we present the recent work on engineering lignin-based multifunctional materials devised through combined catalysis. Despite the fruitful employment of this concept to material design and the fact that engineering has provided multifaceted materials able to solve a broad spectrum of challenges, we envision further exploration and expansion of this important concept in material science beyond the catalytic processes mentioned above. This could be accomplished by taking inspiration from organic synthesis where this concept has been successfully developed and implemented.
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| 2. |
- Afewerki, Samson, et al.
(författare)
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Combined Catalysis for Engineering Bioinspired, Lignin-Based, Long-Lasting, Adhesive, Self-Mending, Antimicrobial Hydrogels
- 2020
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 14:12, s. 17004-17017
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Tidskriftsartikel (refereegranskat)abstract
- The engineering of multifunctional biomaterials using a facile sustainable methodology that follows the principles of green chemistry is still largely unexplored but would be very beneficial to the world. Here, the employment of catalytic reactions in combination with biomass-derived starting materials in the design of biomaterials would promote the development of eco-friendly technologies and sustainable materials. Herein, we disclose the combination of two catalytic cycles (combined catalysis) comprising oxidative decarboxylation and quinone-catechol redox catalysis for engineering lignin-based multifunctional antimicrobial hydrogels. The bioinspired design mimics the catechol chemistry employed by marine mussels in nature. The resultant multifunctional sustainable hydrogels (1) are robust and elastic, (2) have strong antimicrobial activity, (3) are adhesive to skin tissue and various other surfaces, and (4) are able to self-mend. A systematic characterization was carried out to fully elucidate and understand the facile and efficient catalytic strategy and the subsequent multifunctional materials. Electron paramagnetic resonance analysis confirmed the long-lasting quinone-catechol redox environment within the hydrogel system. Initial in vitro biocompatibility studies demonstrated the low toxicity of the hydrogels. This proof-of-concept strategy could be developed into an important technological platform for the eco-friendly, bioinspired design of other multifunctional hydrogels and their use in various biomedical and flexible electronic applications.
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| 3. |
- Aliakbarinodehi, Nima, 1986, et al.
(författare)
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Interaction Kinetics of Individual mRNA-Containing Lipid Nanoparticles with an Endosomal Membrane Mimic: Dependence on pH, Protein Corona Formation, and Lipoprotein Depletion
- 2022
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 16:12, s. 20163-20173
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Tidskriftsartikel (refereegranskat)abstract
- Lipid nanoparticles (LNPs) have emerged as potent carriers for mRNA delivery, but several challenges remain before this approach can offer broad clinical translation of mRNA therapeutics. To improve their efficacy, a better understanding is required regarding how LNPs are trapped and processed at the anionic endosomal membrane prior to mRNA release. We used surface-sensitive fluorescence microscopy with single LNP resolution to investigate the pH dependency of the binding kinetics of ionizable lipid-containing LNPs to a supported endosomal model membrane. A sharp increase of LNP binding was observed when the pH was lowered from 6 to 5, accompanied by stepwise large-scale LNP disintegration. For LNPs preincubated in serum, protein corona formation shifted the onset of LNP binding and subsequent disintegration to lower pH, an effect that was less pronounced for lipoprotein-depleted serum. The LNP binding to the endosomal membrane mimic was observed to eventually become severely limited by suppression of the driving force for the formation of multivalent bonds during LNP attachment or, more specifically, by charge neutralization of anionic lipids in the model membrane due to their association with cationic lipids from earlier attached LNPs upon their disintegration. Cell uptake experiments demonstrated marginal differences in LNP uptake in untreated and lipoprotein-depleted serum, whereas lipoprotein-depleted serum increased mRNA-controlled protein (eGFP) production substantially. This complies with model membrane data and suggests that protein corona formation on the surface of the LNPs influences the nature of the interaction between LNPs and endosomal membranes.
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| 4. |
- Aliakbarinodehi, Nima, 1986, et al.
(författare)
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Time-Resolved Inspection of Ionizable Lipid-Facilitated Lipid Nanoparticle Disintegration and Cargo Release at an Early Endosomal Membrane Mimic
- 2024
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Ingår i: ACS Nano. - 1936-086X .- 1936-0851. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- Advances in lipid nanoparticle (LNP) design have contributed notably to the emergence of the current clinically approved mRNA-based vaccines and are of high relevance for delivering mRNA to combat diseases where therapeutic alternatives are sparse. LNP-assisted mRNA delivery utilizes ionizable lipid-mediated cargo translocation across the endosomal membrane driven by the acidification of the endosomal environment. However, this process occurs at a low efficiency, a few percent at the best. Utilizing surface-sensitive fluorescence microscopy with a single LNP and mRNA resolution, we have investigated pH-controlled interactions between individual LNPs and a planar anionic supported lipid bilayer (SLB) formed on nanoporous silica, mimicking the electrostatic conditions of the early endosomal membrane. For LNPs with an average diameter of 140 nm, fusion with the anionic SLB preferentially occurred when the pH was reduced from 6.6 to 6.0. Furthermore, there was a delay in the onset of LNP fusion after the pH drop, and upon fusion, a significant fraction (>70%) of mRNA was released into the acidic solution representing the endosomal lumen, while a fraction of mRNA remained bound to the SLB even after reversing the pH to neutral cytosolic conditions. Finally, a comparison of the fusion efficiency of two LNP formulations with different surface concentrations of gel-forming lipids correlated with differences in the protein translation efficiency previously observed in human primary cell transfection studies. Together, these findings emphasize the relevance of biophysical investigations of ionizable lipid-containing LNP-assisted mRNA delivery mechanisms while potentially also offering means to optimize the design of LNPs with enhanced endosomal escape capabilities.
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| 5. |
- Alijani, Hossein, et al.
(författare)
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Acoustomicrofluidic Synthesis of Pristine Ultrathin Ti3C2Tz MXene Nanosheets and Quantum Dots
- 2021
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Ingår i: ACS Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 15:7, s. 12099-12108
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Tidskriftsartikel (refereegranskat)abstract
- The conversion of layered transition metal carbides and/or nitrides (MXenes) into zero-dimensional structures with thicknesses and lateral dimensions of a few nanometers allows these recently discovered materials with exceptional electronic properties to exploit the additional benefits of quantum confinement, edge effects, and large surface area. Conventional methods for the conversion of MXene nanosheets and quantum dots, however, involve extreme conditions such as high temperatures and/or harsh chemicals that, among other disadvantages, lead to significant degradation of the material as a consequence of their oxidation. Herein, we show that the large surface acceleration.on the order of 10 million gs.produced by high-frequency (10 MHz) nanometer-order electromechanical vibrations on a chipscale piezoelectric substrate is capable of efficiently nebulizing, and consequently dimensionally reducing, a suspension of multilayer Ti3C2Tz (MXene) into predominantly monolayer nanosheets and quantum dots while, importantly, preserving the material from any appreciable oxidation. As an example application, we show that the high-purity MXene quantum dots produced using this room-temperature chemical-free synthesis method exhibit superior performance as electrode materials for electrochemical sensing of hydrogen peroxide compared to the highly oxidized samples obtained through conventional hydrothermal synthesis. The ability to detect concentrations as low as 5 nM is a 10-fold improvement to the best reported performance of Ti3C2Tz MXene electrochemical sensors to date.
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| 6. |
- Alizadehgiashi, Moien, et al.
(författare)
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Multifunctional 3D-Printed Wound Dressings
- 2021
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:7, s. 12375-12387
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Tidskriftsartikel (refereegranskat)abstract
- Personalized wound dressings provide enhanced healing for different wound types; however multicomponent wound dressings with discretely controllable delivery of different biologically active agents are yet to be developed. Here we report 3D-printed multicomponent biocomposite hydrogel wound dressings that have been selectively loaded with small molecules, metal nanoparticles, and proteins for independently controlled release at the wound site. Hydrogel wound dressings carrying antibacterial silver nanoparticles and vascular endothelial growth factor with predetermined release profiles were utilized to study the physiological response of the wound in a mouse model. Compared to controls, the application of dressings resulted in improvement in granulation tissue formation and differential levels of vascular density, dependent on the release profile of the growth factor. Our study demonstrates the versatility of the 3D-printed hydrogel dressings that can yield varied physiological responses in vivo and can further be adapted for personalized treatment of various wound types.
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| 7. |
- Altenburger, Björn, 1990, et al.
(författare)
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Label-Free Imaging of Catalytic H 2 O 2 Decomposition on Single Colloidal Pt Nanoparticles Using Nanofluidic Scattering Microscopy
- 2023
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Ingår i: ACS Nano. - 1936-086X .- 1936-0851. ; 17:21, s. 21030-21043
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Tidskriftsartikel (refereegranskat)abstract
- Single-particle catalysis aims at determining factors that dictate the nanoparticle activity and selectivity. Existing methods often use fluorescent model reactions at low reactant concentrations, operate at low pressures, or rely on plasmonic enhancement effects. Hence, methods to measure single-nanoparticle activity under technically relevant conditions and without fluorescence or other enhancement mechanisms are still lacking. Here, we introduce nanofluidic scattering microscopy of catalytic reactions on single colloidal nanoparticles trapped inside nanofluidic channels to fill this gap. By detecting minuscule refractive index changes in a liquid flushed trough a nanochannel, we demonstrate that local H2O2 concentration changes in water can be accurately measured. Applying this principle, we analyze the H2O2 concentration profiles adjacent to single colloidal Pt nanoparticles during catalytic H2O2 decomposition into O2 and H2O and derive the particles’ individual turnover frequencies from the growth rate of the O2 gas bubbles formed in their respective nanochannel during reaction.
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| 8. |
- Andersson, Carl, 1996, et al.
(författare)
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A Microshutter for the Nanofabrication of Plasmonic Metal Alloys with Single Nanoparticle Composition Control
- 2023
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Ingår i: ACS Nano. - 1936-086X .- 1936-0851. ; 17:16, s. 15978-15988
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Tidskriftsartikel (refereegranskat)abstract
- Alloying offers an increasingly important handle in nanomaterials design in addition to the already widely explored size and geometry of nanostructures of interest. As the key trait, the mixing of elements at the atomic level enables nanomaterials with physical or chemical properties that cannot be obtained by a single element alone, and subtle compositional variations can significantly impact these properties. Alongside the great potential of alloying, the experimental scrutiny of its impact on nanomaterial function is a challenge because the parameter space that encompasses nanostructure size, geometry, chemical composition, and structural atomic-level differences among individuals is vast and requires unrealistically large sample sets if statistically relevant and systematic data are to be obtained. To address this challenge, we have developed a microshutter device for spatially highly resolved physical vapor deposition in the lithography-based fabrication of nanostructured surfaces. As we demonstrate, it enables establishing compositional gradients across a surface with single nanostructure resolution in terms of alloy composition, which subsequently can be probed in a single experiment. As a showcase, we have nanofabricated arrays of AuAg, AuPd, and AgPd alloy nanoparticles with compositions systematically controlled at the level of single particle rows, as verified by energy dispersive X-ray and single particle plasmonic nanospectroscopy measurements, which we also compared to finite-difference time-domain simulations. Finally, motivated by their application in state-of-the-art plasmonic hydrogen sensors, we investigated PdAu alloy gradient arrays for their hydrogen sorption properties. We found distinctly composition-dependent kinetics and hysteresis and revealed a composition-dependent contribution of a single nanoparticle response to the ensemble average, which highlights the importance of alloy composition screening in single experiments with single nanoparticle resolution, as offered by the microshutter nanofabrication approach.
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| 9. |
- Ansari, Shaquib Rahman, et al.
(författare)
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Pharmaceutical Quality by Design Approach to Develop High-Performance Nanoparticles for Magnetic Hyperthermia
- 2024
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Ingår i: ACS Nano. - 1936-0851 .- 1936-086X. ; 18:23, s. 15284-15302
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic hyperthermia holds significant therapeutic potential, yet its clinical adoption faces challenges. One obstacle is the large-scale synthesis of high-quality superparamagnetic iron oxide nanoparticles (SPIONs) required for inducing hyperthermia. Robust and scalable manufacturing would ensure control over the key quality attributes of SPIONs, and facilitate clinical translation and regulatory approval. Therefore, we implemented a risk-based pharmaceutical quality by design (QbD) approach for SPION production using flame spray pyrolysis (FSP), a scalable technique with excellent batch-to-batch consistency. A design of experiments method enabled precise size control during manufacturing. Subsequent modeling linked the SPION size (6–30 nm) and composition to intrinsic loss power (ILP), a measure of hyperthermia performance. FSP successfully fine-tuned the SPION composition with dopants (Zn, Mn, Mg), at various concentrations. Hyperthermia performance showed a strong nonlinear relationship with SPION size and composition. Moreover, the ILP demonstrated a stronger correlation to coercivity and remanence than to the saturation magnetization of SPIONs. The optimal operating space identified the midsized (15–18 nm) Mn0.25Fe2.75O4 as the most promising nanoparticle for hyperthermia. The production of these nanoparticles on a pilot scale showed the feasibility of large-scale manufacturing, and cytotoxicity investigations in multiple cell lines confirmed their biocompatibility. In vitro hyperthermia studies with Caco-2 cells revealed that Mn0.25Fe2.75O4 nanoparticles induced 80% greater cell death than undoped SPIONs. The systematic QbD approach developed here incorporates process robustness, scalability, and predictability, thus, supporting the clinical translation of high-performance SPIONs for magnetic hyperthermia.
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| 10. |
- Baginski, Maciej, et al.
(författare)
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Understanding and Controlling the Crystallization Process in Reconfigurable Plasmonic Superlattices
- 2021
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:3, s. 4916-4926
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Tidskriftsartikel (refereegranskat)abstract
- The crystallization of nanomaterials is a primary source of solid-state, photonic structures. Thus, a detailed understanding of this process is of paramount importance for the successful application of photonic nanomaterials in emerging optoelectronic technologies. While colloidal crystallization has been thoroughly studied, for example, with advanced in situ electron microscopy methods, the noncolloidal crystallization (freezing) of nanoparticles (NPs) remains so far unexplored. To fill this gap, in this work, we present proof-of-principle experiments decoding a crystallization of reconfigurable assemblies of NPs at a solid state. The chosen material corresponds to an excellent testing bed, as it enables both in situ and ex situ investigation using X-ray diffraction ( XRD), transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), atomic force microscopy (AFM), and optical spectroscopy in visible and ultraviolet range (UV-vis) techniques. In particular, ensemble measurements with small-angle XRD highlighted the dependence of the correlation length in the NPs assemblies on the number of heating/cooling cycles and the rate of cooling. Ex situ TEM imaging further supported these results by revealing a dependence of domain size and structure on the sample preparation route and by showing we can control the domain size over 2 orders of magnitude. The application of HAADF-STEM tomography, combined with in situ thermal control, provided three-dimensional single-particle level information on the positional order evolution within assemblies. This combination of real and reciprocal space provides insightful information on the anisotropic, reversibly reconfigurable assemblies of NPs. TEM measurements also highlighted the importance of interfaces in the polydomain structure of nanoparticle solids, allowing us to understand experimentally observed differences in UV-vis extinction spectra of the differently prepared crystallites. Overall, the obtained results show that the combination of in situ heating HAADF-STEM tomography with XRD and ex situ TEM techniques is a powerful approach to study nanoparticle freezing processes and to reveal the crucial impact of disorder in the solid-state aggregates of NPs on their plasmonic properties.
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| 11. |
- Bazylińska, Urszula, et al.
(författare)
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Hybrid Theranostic Cubosomes for Efficient NIR-Induced Photodynamic Therapy
- 2022
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 16:4, s. 5427-5438
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, lipid bicontinuous cubic liquid-crystalline nanoparticles known as cubosomes have been under investigation because of their favorable properties as drug nanocarriers useful for anticancer treatments. Herein, we present organic/inorganic hybrid, theranostic cubosomes stabilized in water with a shell of alternate layers of chitosan, single strand DNA (model genetic material for potential gene therapy), and folic acid-chitosan conjugate (the outmost layer), coencapsulating up-converting Er3+ and Yb3+ codoped NaYF4 nanoparticles and daunorubicin. The latter acts as a chemotherapeutic drug of photosensitizing activity, while up-converting nanoparticles serve as energy harvester and diagnostic agent. Cellular uptake and NIR-induced photodynamic therapy were evaluated in vitro against human skin melanoma (MeWo) and ovarian (SKOV-3) cancer cells. Results evidenced the preferential uptake of the theranostic cubosomes in SKOV-3 cells in comparison to uptake in MeWo cells, and this effect was enhanced by the folic acid functionalization of the cubosomes surface. Nanocarriers coloaded with the hybrid fluorophores exhibited a superior NIR-induced photodynamic activity, also confirmed by the improved mitochondrial activity and the most affecting f-actin fibers of cytoskeleton. Similar results, but with higher photocytotoxicity, were detected when folic acid-functionalized cubosomes were incubated with SKOV-3 cells. Taken on the whole, these results prove these hybrid cubosomes are good candidates for the photodynamic treatment of tumor lesions.
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| 12. |
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| 13. |
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| 14. |
- Bost, J. P., et al.
(författare)
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Delivery of Oligonucleotide Therapeutics: Chemical Modifications, Lipid Nanoparticles, and Extracellular Vesicles
- 2021
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Ingår i: Acs Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:9, s. 13993-14021
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Tidskriftsartikel (refereegranskat)abstract
- Oligonucleotides (ONs) comprise a rapidly growing class of therapeutics. In recent years, the list of FDA-approved ON therapies has rapidly expanded. ONs are small (15-30 bp) nucleotide-based therapeutics which are capable of targeting DNA and RNA as well as other biomolecules. ONs can be subdivided into several classes based on their chemical modifications and on the mechanisms of their target interactions. Historically, the largest hindrance to the widespread usage of ON therapeutics has been their inability to effectively internalize into cells and escape from endosomes to reach their molecular targets in the cytosol or nucleus. While cell uptake has been improved, "endosomal escape" remains a significant problem. There are a range of approaches to overcome this, and in this review, we focus on three: altering the chemical structure of the ONs, formulating synthetic, lipid-based nanoparticles to encapsulate the ONs, or biologically loading the ONs into extracellular vesicles. This review provides a background to the design and mode of action of existing FDA-approved ONs. It presents the most common ON classifications and chemical modifications from a fundamental scientific perspective and provides a roadmap of the cellular uptake pathways by which ONs are trafficked. Finally, this review delves into each of the above-mentioned approaches to ON delivery, highlighting the scientific principles behind each and covering recent advances.
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| 15. |
- Bretscher, Hope, et al.
(författare)
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Rational Passivation of Sulfur Vacancy Defects in Two-Dimensional Transition Metal Dichalcogenides
- 2021
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:5, s. 8780-8789
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Tidskriftsartikel (refereegranskat)abstract
- Structural defects vary the optoelectronic properties of monolayer transition metal dichalcogenides, leading to concerted efforts to control defect type and density via materials growth or postgrowth passivation. Here, we explore a simple chemical treatment that allows on-off switching of low-lying, defect-localized exciton states, leading to tunable emission properties. Using steady-state and ultrafast optical spectroscopy, supported by ab initio calculations, we show that passivation of sulfur vacancy defects, which act as exciton traps in monolayer MoS2 and WS2, allows for controllable and improved mobilities and an increase in photoluminescence up to 275-fold, more than twice the value achieved by other chemical treatments. Our findings suggest a route for simple and rational defect engineering strategies for tunable and switchable electronic and excitonic properties through passivation.
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| 16. |
- Burger, Paul, 1997, et al.
(författare)
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Atomic Force Manipulation of Single Magnetic Nanoparticles for Spin-Based Electronics
- 2022
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Ingår i: ACS Nano. - : American Chemical Society. - 1936-0851 .- 1936-086X. ; 16:11, s. 19253-19260
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic nanoparticles (MNPs) are instrumental for fabrication of tailored nanomagnetic structures, especially where top-down lithographic patterning is not feasible. Here, we demonstrate precise and controllable manipulation of individual magnetite MNPs using the tip of an atomic force microscope. We verify our approach by placing a single MNP with a diameter of 50 nm on top of a 100 nm Hall bar fabricated in a quasi-two-dimensional electron gas (q2DEG) at the oxide interface between LaAlO3 and SrTiO3 (LAO/STO). A hysteresis loop due to the magnetic hysteresis properties of the magnetite MNPs was observed in the Hall resistance. Further, the effective coercivity of the Hall resistance hysteresis loop could be changed upon field cooling at different angles of the cooling field with respect to the measuring field. The effect is associated with the alignment of the MNP magnetic moment along the easy axis closest to the external field direction across the Verwey transition in magnetite. Our results can facilitate experimental realization of magnetic proximity devices using single MNPs and two-dimensional materials for spin-based nanoelectronics. © 2022 The Authors.
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| 17. |
- Bykov, Maxim, et al.
(författare)
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Realization of an Ideal Cairo Tessellation in Nickel Diazenide NiN2: High-Pressure Route to Pentagonal 2D Materials
- 2021
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Ingår i: ACS Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 15:8, s. 13539-13546
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Tidskriftsartikel (refereegranskat)abstract
- Most of the studied two-dimensional (2D) materials are based on highly symmetric hexagonal structural motifs. In contrast, lower-symmetry structures may have exciting anisotropic properties leading to various applications in nano-electronics. In this work we report the synthesis of nickel diazenide NiN2 which possesses atomic-thick layers comprised of Ni2N3 pentagons forming Cairo-type tessellation. The layers of NiN2 are weakly bonded with the calculated exfoliation energy of 0.72 J/m(2), which is just slightly larger than that of graphene. The compound crystallizes in the space group of the ideal Cairo tiling (P4/mbm) and possesses significant anisotropy of elastic properties. The single-layer NiN2 is a direct-band-gap semiconductor, while the bulk material is metallic. This indicates the promise of NiN2 to be a precursor of a pentagonal 2D material with a tunable direct band gap.
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| 18. |
- Canales Ramos, Adriana, 1993, et al.
(författare)
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Perfect Absorption and Strong Coupling in Supported MoS 2 Multilayers
- 2023
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 17:4, s. 3401-3411
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Tidskriftsartikel (refereegranskat)abstract
- Perfect absorption and strong coupling are two highly sought-after regimes of light-matter interactions. Both regimes have been studied as separate phenomena in excitonic 2D materials, particularly in MoS2. However, the structures used to reach these regimes often require intricate nanofabrication. Here, we demonstrate the occurrence of perfect absorption and strong coupling in thin MoS2 multilayers supported by a glass substrate. We measure reflection spectra of mechanically exfoliated MoS2 flakes at various angles beyond the light-line via Fourier plane imaging and spectroscopy and find that absorption in MoS2 monolayers increases up to 74% at the C-exciton by illuminating at the critical angle. Perfect absorption is achieved for ultrathin MoS2 flakes (4-8 layers) with a notable angle and frequency sensitivity to the exact number of layers. By calculating zeros and poles of the scattering matrix in the complex frequency plane, we identify perfect absorption (zeros) and strong coupling (poles) conditions for thin (<10 layers) and thick (>10 layers) limits. Our findings reveal rich physics of light-matter interactions in bare MoS2 flakes, which could be useful for nanophotonic and light harvesting applications.
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| 19. |
- Cautela, Jacopo, et al.
(författare)
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Supracolloidal Atomium
- 2020
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 14:11, s. 15748-15756
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Tidskriftsartikel (refereegranskat)abstract
- Nature suggests that complex materials result from a hierarchical organization of matter at different length scales. At the nano- and micrometer scale, macromolecules and supramolecular aggregates spontaneously assemble into supracolloidal structures whose complexity is given by the coexistence of various colloidal entities and the specific interactions between them. Here, we demonstrate how such control can be implemented by engineering specially customized bile salt derivative-based supramolecular tubules that exhibit a highly specific interaction with polymeric microgel spheres at their extremities thanks to their scroll-like structure. This design allows for hierarchical supracolloidal self-assembly of microgels and supramolecular scrolls into a regular framework of “nodes” and “linkers”. The supramolecular assembly into scrolls can be triggered by pH and temperature, thereby providing the whole supracolloidal system with interesting stimuli-responsive properties. A colloidal smart assembly is embodied with features of center-linker frameworks as those found in molecular metal–organic frameworks and in structures engineered at human scale, masterfully represented by the Atomium in Bruxelles.
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| 20. |
- Chen, Gan, et al.
(författare)
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Effects of Transition Metals on Metal–Octaaminophthalocyanine-Based 2D Metal–Organic Frameworks
- 2023
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Ingår i: ACS Nano. - 1936-0851 .- 1936-086X. ; 17:10, s. 9611-9621
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Tidskriftsartikel (refereegranskat)abstract
- Metal–octaaminophthalocyanine (MOAPc)-based 2D conductive metal–organic frameworks (cMOFs) have shown great potential in several applications, including sensing, energy storage, and electrocatalysis, due to their bimetallic characteristics. Here, we report a detailed metal substitution study on a family of isostructural cMOFs with Co2+, Ni2+, and Cu2+ as both the metal nodes and the metal centers in the MOAPc ligands. We observed that different metal nodes had variations in the reaction kinetics, particle sizes, and crystallinities. Importantly, the electronic structure and conductivity were found to be dependent on both types of metal sites in the 2D cMOFs. Ni-NiOAPc was found to be the most conductive one among the nine possible combinations with a conductivity of 54 ± 4.8 mS/cm. DFT calculations revealed that monolayer Ni-NiOAPc has neither the smallest bandgap nor the highest charge carrier mobility. Hence its highest conductivity stems from its high crystallinity. Collectively, these results provide structure property relationships for MOAPc-based cMOFs with amino coordination units.
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| 21. |
- Chen, H., et al.
(författare)
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Color-Switchable Nanosilicon Fluorescent Probes
- 2022
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 16:9, s. 15450-15459
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescent probes are vital to cell imaging by allowing specific parts of cells to be visualized and quantified. Color-switchable probes (CSPs), with tunable emission wavelength upon contact with specific targets, are particularly powerful because they not only eliminate the need to wash away all unbound probe but also allow for internal controls of probe concentrations, thereby facilitating quantification. Several such CSPs exist and have proven very useful, but not for all key cellular targets. Here we report a pioneering CSP for in situ cell imaging using aldehyde-functionalized silicon nanocrystals (SiNCs) that switch their intrinsic photoluminescence from red to blue quickly when interacting with amino acids in live cells. Though conventional probes often work better in cell-free extracts than in live cells, the SiNCs display the opposite behavior and function well and fast in universal cell lines at 37 °C while requiring much higher temperature in extracts. Furthermore, the SiNCs only disperse in cytoplasm not nucleus, and their fluorescence intensity correlated linearly with the concentration of fed amino acids. We believe these nanosilicon probes will be promising tools to visualize distribution of amino acids and potentially quantify amino acid related processes in live cells.
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| 22. |
- Chikina, Alla, et al.
(författare)
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Band-Order Anomaly at the gamma-Al2O3/SrTiO3 Interface Drives the Electron-Mobility Boost
- 2021
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:3, s. 4347-4356
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Tidskriftsartikel (refereegranskat)abstract
- The rich functionalities of transition-metal oxides and their interfaces bear an enormous technological potential. Its realization in practical devices requires, however, a significant improvement of yet relatively low electron mobility in oxide materials. Recently, a mobility boost of about 2 orders of magnitude has been demonstrated at the spinel-perovskite gamma-Al2O3/SrTiO3 interface compared to the paradigm perovskite-perovskite LaAlO3/SrTiO3 interface. We explore the fundamental physics behind this phenomenon from direct measurements of the momentum-resolved electronic structure of this interface using resonant soft-X-ray angle-resolved photoemission. We find an anomaly in orbital ordering of the mobile electrons in gamma-Al2O3/SrTiO3 which depopulates electron states in the top SrTiO3 layer. This rearrangement of the mobile electron system pushes the electron density away from the interface, which reduces its overlap with the interfacial defects and weakens the electron-phonon interaction, both effects contributing to the mobility boost. A crystal-field analysis shows that the band order alters owing to the symmetry breaking between the spinel gamma-Al2O3 and perovskite SrTiO3. Band-order engineering, exploiting the fundamental symmetry properties, emerges as another route to boost the performance of oxide devices.
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| 23. |
- Dematties, Dario, et al.
(författare)
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Deep Learning of Nanopore Sensing Signals Using a Bi-Path Network
- 2021
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:9, s. 14419-14429
-
Tidskriftsartikel (refereegranskat)abstract
- Temporal changes in electrical resistance of a nanopore sensor caused by translocating target analytes are recorded as a sequence of pulses on current traces. Prevalent algorithms for feature extraction in pulse-like signals lack objectivity because empirical amplitude thresholds are user-defined to single out the pulses from the noisy background. Here, we use deep learning for feature extraction based on a bipath network (B-Net). After training, the B-Net acquires the prototypical pulses and the ability of both pulse recognition and feature extraction without a priori assigned parameters. The B-Net is evaluated on simulated data sets and further applied to experimental data of DNA and protein translocation. The B-Net results are characterized by small relative errors and stable trends. The B-Net is further shown capable of processing data with a signal-to-noise ratio equal to 1, an impossibility for threshold-based algorithms. The B-Net presents a generic architecture applicable to pulse-like signals beyond nanopore currents.
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| 24. |
- Dey, Amrita, et al.
(författare)
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State of the Art and Prospects for Halide Perovskite Nanocrystals
- 2021
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:7, s. 10775-10981
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Tidskriftsartikel (refereegranskat)abstract
- Metal-halide perovskites have rapidly emerged as one of the most promising materials of the 21st century, with many exciting properties and great potential for a broad range of applications, from photovoltaics to optoelectronics and photocatalysis. The ease with which metal-halide perovskites can be synthesized in the form of brightly luminescent colloidal nanocrystals, as well as their tunable and intriguing optical and electronic properties, has attracted researchers from different disciplines of science and technology. In the last few years, there has been a significant progress in the shape-controlled synthesis of perovskite nanocrystals and understanding of their properties and applications. In this comprehensive review, researchers having expertise in different fields (chemistry, physics, and device engineering) of metal-halide perovskite nanocrystals have joined together to provide a state of the art overview and future prospects of metal-halide perovskite nanocrystal research. © 2021 American Chemical Society.
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| 25. |
- Downes, Marley, et al.
(författare)
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M5X4: A Family of MXenes
- 2023
-
Ingår i: ACS Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 17:17, s. 17158-17168
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Tidskriftsartikel (refereegranskat)abstract
- MXenes are two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides typically synthesized from layered MAX-phase precursors. With over 50 experimentally reported MXenes and a near-infinite number of possible chemistries, MXenes make up the fastest-growing family of 2D materials. They offer a wide range of properties, which can be altered by their chemistry (M, X) and the number of metal layers in the structure, ranging from two in M2XTx to five in M5X4T x . Only one M5X4 MXene, Mo4VC4, has been reported. Herein, we report the synthesis and characterization of two M(5)AX(4) mixed transition metal MAX phases, Ti2.5Ta2.5AlC4 and Ti2.675Nb2.325AlC4, and their successful topochemical transformation into Ti2.5Ta2.5C4T x and Ti2.675Nb2.325C4Tx MXenes. The resulting MXenes were delaminated into single-layer flakes, analyzed structurally, and characterized for their thermal and optical properties. This establishes a family of M(5)AX(4) MAX phases and their corresponding MXenes. These materials were experimentally produced based on guidance from theoretical predictions, leading to more exciting applications for MXenes.
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| 26. |
- Dürr, Robin N., et al.
(författare)
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From NiMoO4 to γ-NiOOH : Detecting the Active Catalyst Phase by Time Resolved in Situ and Operando Raman Spectroscopy
- 2021
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:8, s. 13504-13515
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Tidskriftsartikel (refereegranskat)abstract
- Water electrolysis powered by renewable energies is a promising technology to produce sustainable fossil free fuels. The development and evaluation of effective catalysts are here imperative; however, due to the inclusion of elements with different redox properties and reactivity, these materials undergo dynamical changes and phase transformations during the reaction conditions. NiMoO4 is currently investigated among other metal oxides as a promising noble metal free catalyst for the oxygen evolution reaction. Here we show that at applied bias, NiMoO4·H2O transforms into γ-NiOOH. Time resolved operando Raman spectroscopy is utilized to follow the potential dependent phase transformation and is collaborated with elemental analysis of the electrolyte, confirming that molybdenum leaches out from the as-synthesized NiMoO4·H2O. Molybdenum leaching increases the surface coverage of exposed nickel sites, and this in combination with the formation of γ-NiOOH enlarges the amount of active sites of the catalyst, leading to high current densities. Additionally, we discovered different NiMoO4 nanostructures, nanoflowers, and nanorods, for which the relative ratio can be influenced by the heating ramp during the synthesis. With selective molybdenum etching we were able to assign the varying X-ray diffraction (XRD) pattern as well as Raman vibrations unambiguously to the two nanostructures, which were revealed to exhibit different stabilities in alkaline media by time-resolved in situ and operando Raman spectroscopy. We advocate that a similar approach can beneficially be applied to many other catalysts, unveiling their structural integrity, characterize the dynamic surface reformulation, and resolve any ambiguities in interpretations of the active catalyst phase.
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| 27. |
- El Ghazaly, Ahmed, et al.
(författare)
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Ultrafast, One-Step, Salt-Solution-Based Acoustic Synthesis of Ti3C2 MXene
- 2021
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:3, s. 4287-4293
-
Tidskriftsartikel (refereegranskat)abstract
- The current quest for two-dimensional transition metal carbides and nitrides (MXenes) has been to circumvent the slow, hazardous, and laborious multistep synthesis procedures associated with conventional chemical MAX phase exfoliation. Here, we demonstrate a one-step synthesis method with local Ti3AlC2 MAX to Ti3C2Tz MXene conversion on the order of milliseconds, facilitated by proton production through solution dissociation under megahertz frequency acoustic excitation. These protons combined with fluorine ions from LiF to selectively etch the MAX phase into MXene, whose delamination is aided by the acoustic forcing. These results have important implications for the future applicability of MXenes, which crucially depend on the development of more efficient synthesis procedures. For proof-of-concept, we show that flexible electrodes fabricated by this method exhibit comparable electrochemical performance to that previously reported.
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| 28. |
- Emilsson, Gustav, 1989, et al.
(författare)
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The In Vivo Fate of Polycatecholamine Coated Nanoparticles Is Determined by a Fibrinogen Enriched Protein Corona
- 2023
-
Ingår i: ACS Nano. - 1936-086X .- 1936-0851. ; 17:24, s. 24725-24742
-
Tidskriftsartikel (refereegranskat)abstract
- Polycatecholamine coatings have attracted significant attention in the past 10 years owing to their ability to functionalize a wide range of materials. Here we apply the use of such coatings to drug nanocrystals, made from a poorly soluble drug compound, to postfunctionalize the nanocrystal surface with the aim of providing steric stabilization and extending their circulation time after intravenous injection. We show that both polydopamine and polynorepinephrine can be used to successfully modify drug nanocrystals and subsequently incorporate end-functionalized PEG to the surface. Even though high grafting densities of PEG were achieved, we observed rapid clearance and increased liver uptake for polycatecholamine functionalized drug nanocrystals. Using both surface sensitive model systems and protein corona profiling, we determine that the rapid clearance was correlated with an increase in adsorption of proteins involved in coagulation to the polycatecholamine surface, with fibrinogen being the most abundant. Further analysis of the most abundant proteins revealed a significant increase in thiol-rich proteins on polycatecholamine coated surfaces. The observed interaction with coagulation proteins highlights one of the current challenges using polycatecholamines for drug delivery but might also provide insights to the growing use of these materials in hemostatic applications.
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| 29. |
- Enrico, Alessandro, et al.
(författare)
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Ultrafast and Resist-Free Nanopatterning of 2D Materials by Femtosecond Laser Irradiation
- 2023
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 17:9, s. 8041-8052
-
Tidskriftsartikel (refereegranskat)abstract
- The performance of two-dimensional (2D) materials is promising for electronic, photonic, and sensing devices since they possess large surface-to-volume ratios, high mechanical strength, and broadband light sensitivity. While significant advances have been made in synthesizing and transferring 2D materials onto different substrates, there is still the need for scalable patterning of 2D materials with nanoscale precision. Conventional lithography methods require protective layers such as resist or metals that can contaminate or degrade the 2D materials and deteriorate the final device performance. Current resist-free patterning methods are limited in throughput and typically require custom-made equipment. To address these limitations, we demonstrate the noncontact and resist-free patterning of platinum diselenide (PtSe2), molybdenum disulfide (MoS2), and graphene layers with nanoscale precision at high processing speed while preserving the integrity of the surrounding material. We use a commercial, off-the-shelf two-photon 3D printer to directly write patterns in the 2D materials with features down to 100 nm at a maximum writing speed of 50 mm/s. We successfully remove a continuous film of 2D material from a 200 μm × 200 μm substrate area in less than 3 s. Since two-photon 3D printers are becoming increasingly available in research laboratories and industrial facilities, we expect this method to enable fast prototyping of devices based on 2D materials across various research areas.
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| 30. |
- Eom, Namsoon, et al.
(författare)
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General Trends in Core-Shell Preferences for Bimetallic Nanoparticles
- 2021
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:5, s. 8883-8895
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Tidskriftsartikel (refereegranskat)abstract
- Surface segregation phenomena dictate core-shell preference of bimetallic nanoparticles and thus play a crucial role in the nanoparticle synthesis and applications. Although it is generally agreed that surface segregation depends on the constituent materials' physical properties, a comprehensive picture of the phenomena on the nanoscale is not yet complete. Here we use a combination of molecular dynamics (MD) and Monte Carlo (MC) simulations on 45 bimetallic combinations to determine the general trend on the core-shell preference and the effects of size and composition. From the extensive studies over sizes and compositions, we find that the surface segregation and degree of the core-shell tendency of the bimetallic combinations depend on the sufficiency or scarcity of the surface-preferring material. Principal component analysis (PCA) and linear discriminant analysis (LDA) on the molecular dynamics simulations results reveal that cohesive energy and Wigner-Seitz radius are the two primary factors that have an "additive"effect on the segregation level and core-shell preference in the bimetallic nanoparticles studied. When the element with the higher cohesive energy also has the larger Wigner-Seitz radius, its core preference decreases, and thus this combination forms less segregated structures than what one would expect from the cohesive energy difference alone. Highly segregated structures (highly segregated core-shell or Janus-like) are expected to form when both the relative cohesive energy difference is greater than ∼20%, and the relative Wigner-Seitz radius difference is greater than ∼4%. Practical guides for predicting core-shell preference and degree of segregation level are presented.
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| 31. |
- Eriksson, Fredrik, 1992, et al.
(författare)
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Tuning the Through-Plane Lattice Thermal Conductivity in van der Waals Structures through Rotational (Dis)ordering
- 2023
-
Ingår i: ACS Nano. - 1936-086X .- 1936-0851. ; 17:24, s. 25565-25574
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Tidskriftsartikel (refereegranskat)abstract
- It has recently been demonstrated that MoS2 with irregular interlayer rotations can achieve an extreme anisotropy in the lattice thermal conductivity (LTC), which is, for example, of interest for applications in waste heat management in integrated circuits. Here, we show by atomic-scale simulations based on machine-learned potentials that this principle extends to other two-dimensional materials, including C and BN. In all three materials, introducing rotational disorder drives the through-plane LTC to the glass limit, while the in-plane LTC remains almost unchanged compared to those of the ideal bulk materials. We demonstrate that the ultralow through-plane LTC is connected to the collapse of their transverse acoustic modes in the through-plane direction. Furthermore, we find that the twist angle in periodic moiré structures representing rotational order provides an efficient means for tuning the through-plane LTC that operates for all chemistries considered here. The minimal through-plane LTC is obtained for angles between 1 and 4° depending on the material, with the biggest effect in MoS2. The angular dependence is correlated with the degree of stacking disorder in the materials, which in turn is connected to the slip surface. This provides a simple descriptor for predicting the optimal conditions at which the LTC is expected to become minimal.
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| 32. |
- Fang, Trixy, et al.
(författare)
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Spatial Regulation of T-Cell Signaling by Programmed Death-Ligand 1 on Wireframe DNA Origami Flat Sheets
- 2021
-
Ingår i: ACS Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 15:2, s. 3441-3452
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Tidskriftsartikel (refereegranskat)abstract
- Programmed Death-1 (PD-1) is a coinhibitory receptor expressed on activated T cells that suppresses T-cell signaling and effector functions. It has been previously shown that binding to its ligand PD-L1 induces a spatial reorganization of PD-1 receptors into microclusters on the cell membrane. However, the roles of the spatial organization of PD-L1 on PD-1 clustering and T-cell signaling have not been elucidated. Here, we used DNA origami flat sheets to display PD-L1 ligands at defined nanoscale distances and investigated their ability to inhibit T-cell activation in vitro. We found that DNA origami flat sheets modified with CD3 and CD28 activating antibodies (FS-alpha-CD3-CD28) induced robust T-cell activation. Co-treatment with flat sheets presenting PD-L1 ligands separated by similar to 200 nm (FS-PD-L1-200), but not 13 nm (FS-PD-L1-13) or 40 nm (FS-PD-L1-40), caused an inhibition of T-cell signaling, which increased with increasing molar ratio of FS-PD-L1-200 to FS-alpha-CD3-CD28. Furthermore, FS-PD-L1-200 induced the formation of smaller PD-1 nanoclusters and caused a larger reduction in IL-2 expression compared to FS-PD-L1-13. Together, these findings suggest that the spatial organization of PD-L1 determines its ability to regulate T-cell signaling and may guide the development of future nanomedicine-based immunomodulatory therapies.
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| 33. |
- Fang, Yurui, 1983, et al.
(författare)
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Photoemission Enhancement of Plasmonic Hot Electrons by Au Antenna-Sensitizer Complexes
- 2024
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Ingår i: ACS Nano. - 1936-086X .- 1936-0851. ; 18:4, s. 3397-3404
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Tidskriftsartikel (refereegranskat)abstract
- The photoemission of surface plasmon decay-produced hot electrons is usually of very low efficiencies, hindering the practical utilization of such nonequilibrium charge carriers in harvesting photons with less energy than the semiconductor band gap for more efficient solar energy collection and photodetection. However, it has been demonstrated that the photoemission efficiency of small metal clusters increases as the particle size decreases. Recent studies have also shown that the photoemission efficiency of surface plasmon-yielded hot carriers can be intrinsically improved through proper material construction. In this paper, we report that the photoemission efficiency of hot electrons on the Au nanodisk-cluster complex/TiO2 interface can be dramatically enhanced under optical nanoantenna-sensitizer design. Such an enhancement is dominantly attributed to three factors. First, the large plasmonic nanodisk antennas provide a significantly enhanced optical near field, which largely increases light absorption in the small Au clusters that are acting as hot electron injection sensitizers. Second, the sub-3 nm size of the Au clusters facilitates the collection of delocalized spreading charges by the semiconductor. Third, the hybrid interface and molecule-like energy level of the Au cluster result in a much longer lifetime of excited electrons. Our results provide a promising approach for the effective harvesting of solar energy with plasmonic antenna-sensitizer complexes.
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| 34. |
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| 35. |
- Finizio, Simone, et al.
(författare)
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Periodogram-Based Detection of Unknown Frequencies in Time-Resolved Scanning Transmission X-ray Microscopy
- 2022
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 16:12, s. 21071-21078
-
Tidskriftsartikel (refereegranskat)abstract
- Pump–probe time-resolved imaging is a powerful technique that enables the investigation of dynamical processes. Signal-to-noise and sampling rate restrictions normally require that cycles of an excitation are repeated many times with the final signal reconstructed using a reference. However, this approach imposes restrictions on the types of dynamical processes that can be measured, namely, that they are phase locked to a known external signal (e.g., a driven oscillation or impulse). This rules out many interesting processes such as auto-oscillations and spontaneously forming populations, e.g., condensates. In this work we present a method for time-resolved imaging, based on the Schuster periodogram, that allows for the reconstruction of dynamical processes where the intrinsic frequency is not known. In our case we use time of arrival detection of X-ray photons to reconstruct magnetic dynamics without using a priori information on the dynamical frequency. This proof-of-principle demonstration will allow for the extension of pump–probe time-resolved imaging to the important class of processes where the dynamics are not locked to a known external signal and in its presented formulation can be readily adopted for X-ray imaging and also adapted for wider use.
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| 36. |
- Fojt, Jakub, 1996, et al.
(författare)
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Tailoring Hot-Carrier Distributions of Plasmonic Nanostructures through Surface Alloying
- 2024
-
Ingår i: ACS Nano. - 1936-086X .- 1936-0851. ; 18:8, s. 6398-6405
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Tidskriftsartikel (refereegranskat)abstract
- Alloyed metal nanoparticles are a promising platform for plasmonically enabled hot-carrier generation, which can be used to drive photochemical reactions. Although the non-plasmonic component in these systems has been investigated for its potential to enhance catalytic activity, its capacity to affect the photochemical process favorably has been underexplored by comparison. Here, we study the impact of surface alloy species and concentration on hot-carrier generation in Ag nanoparticles. By first-principles simulations, we photoexcite the localized surface plasmon, allow it to dephase, and calculate spatially and energetically resolved hot-carrier distributions. We show that the presence of non-noble species in the topmost surface layer drastically enhances hot-hole generation at the surface at the expense of hot-hole generation in the bulk, due to the additional d-type states that are introduced to the surface. The energy of the generated holes can be tuned by choice of the alloyant, with systematic trends across the d-band block. Already low surface alloy concentrations have a large impact, with a saturation of the enhancement effect typically close to 75% of a monolayer. Hot-electron generation at the surface is hindered slightly by alloying, but here a judicious choice of the alloy composition allows one to strike a balance between hot electrons and holes. Our work underscores the promise of utilizing multicomponent nanoparticles to achieve enhanced control over plasmonic catalysis and provides guidelines for how hot-carrier distributions can be tailored by designing the electronic structure of the surface through alloying.
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| 37. |
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| 38. |
- Gao, Lingfeng, et al.
(författare)
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Applications of Few-Layer Nb2C MXene : Narrow-Band Photodetectors and Femtosecond Mode-Locked Fiber Lasers
- 2021
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:1, s. 954-965
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Tidskriftsartikel (refereegranskat)abstract
- Although the physicochemical properties of niobium carbide (Nb2C) have been widely investigated, their exploration in the field of photoelectronics is still at the infancy stage with many potential applications that remain to be exploited. Hence, it is demonstrated here that few-layer Nb2C MXene can serve as an excellent building block for both photoelectrochemical-type photodetectors (PDs) and mode-lockers. We show that the photoresponse performance can be readily adjusted by external conditions and that Nb2C NSs exhibit a great potential for narrow-band PDs. The demonstrated mechanism was further confirmed by work functions predicted by density functional theory calculations. In addition, as an optical switch for passively mode-locked fiber lasers, ultrastable pulses can be demonstrated in the telecommunication and mid-infrared regions for Nb2C MXene, and as high as the 69th harmonic order with 411 MHz at the center wavelength of 1882 nm can be achieved. These intriguing results indicate that few-layer Nb2C nanosheets can be used as building blocks for various photoelectronic devices, further broadening the application prospects of two-dimensional MXenes.
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| 39. |
- Gao, Lingfeng, et al.
(författare)
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Optical Properties of Few-Layer Ti3CN MXene : From Experimental Observations to Theoretical Calculations
- 2022
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 16:2, s. 3059-3069
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Tidskriftsartikel (refereegranskat)abstract
- Despite the emerging interest in research and development of Ti3CN MXene nanosheet (NS)-based optoelectronic devices, there is still a lack of in-depth studies of the underlying photophysical processes, like carrier relaxation dynamics and nonlinear photon absorption, operating in such devices, hindering their further and precise design. In this paper, we attempt to remedy the situation by fabricating few-layer Ti3CN NSs via combining selective etching and molecular intercalation and by investigating the carrier relaxation possesses and broadband nonlinear optical responses via transient absorption and Z-scan techniques. These results are complemented by first-principle theoretical analyses of the optical properties. Both saturable absorption and reverse saturable absorption phenomena are observed due to multiphoton absorption effects. The analysis of these results adds to the understanding of the basic photophysical processes, which is anticipated to be beneficial for the further design of MXene-based devices.
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| 40. |
- Garemark, Jonas, et al.
(författare)
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Strong, Shape-Memory Aerogel via Wood Cell Wall Nanoscale Reassembly
- 2023
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 17:5, s. 4775-4789
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Tidskriftsartikel (refereegranskat)abstract
- Polymer shape-memory aerogels (PSMAs) are prospects in various fields of application ranging from aerospace to biomedicine, as advanced thermal insulators, actuators, or sensors. However, the fabrication of PSMAs with good mechanical performance is challenging and is currently dominated by fossil-based polymers. In this work, strong, shape-memory bio-aerogels with high specific surface areas (up to 220 m2/g) and low radial thermal conductivity (0.042 W/mK) were prepared through a one-step treatment of native wood using an ionic liquid mixture of [MTBD]+[MMP]−/DMSO. The aerogel showed similar chemical composition similar to native wood. Nanoscale spatial rearrangement of wood biopolymers in the cell wall and lumen was achieved, resulting in flexible hydrogels, offering design freedom for subsequent aerogels with intricate geometries. Shape-memory function under stimuli of water was reported. The chemical composition and distribution, morphology, and mechanical performance of the aerogel were carefully studied using confocal Raman spectroscopy, AFM, SAXS/WAXS, NMR, digital image correlation, etc. With its simplicity, sustainability, and the broad range of applicability, the methodology developed for nanoscale reassembly of wood is an advancement for the design of biobased shape-memory aerogels.
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| 41. |
- Garemark, Jonas, et al.
(författare)
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Top-Down Approach Making Anisotropic Cellulose Aerogels as Universal Substrates for Multifunctionalization
- 2020
-
Ingår i: ACS Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 14:6, s. 7111-7120
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Tidskriftsartikel (refereegranskat)abstract
- Highly porous, strong aerogels with anisotropic structural properties are of great interest for multifunctional materials for applications including insulators in buildings, filters for oil cleanup, electrical storage devices, etc. Contemporary aerogels are mostly extracted from fossil resources and synthesized from bottom-up techniques, often requiring additional strategies to obtain high anisotropy. In this work, a universal approach to prepare porous, strong, anisotropic aerogels is presented through exploiting the natural hierarchical and anisotropic structure of wood. The preparation comprises nanoscale removal of lignin, followed by dissolution-regeneration of nanofibers, leading to enhanced cell wall porosity with nanofibrillated networks occupying the pore space in the cellular wood structure. The aerogels retain structural anisotropy of natural wood, exhibit specific surface areas up to 247 m(2)/g, and show high compression strength at 95% porosity. This is a record specific area value for wood aerogels/foams and even higher than most cellulose-based aerogels for its assigned strength. The aerogel can serve as a platform for multifunctional composites including scaffolds for catalysis, gas separation, or liquid purification due to its porous matrix or as binder-free electrodes in electronics. To demonstrate the multifunctionality, the aerogels are successfully decorated with metal nanoparticles (Ag) and metal oxide nanoparticles (TiO2) by in situ synthesis, coated by the conductive polymer (PEDOT:PSS), and carbonized to yield conductive aerogels. This approach is found to be a universal way to prepare highly porous anisotropic aerogels.
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| 42. |
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| 43. |
- Gowda, V. Krishne, et al.
(författare)
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Nanofibril Alignment during Assembly Revealed by an X-ray Scattering-Based Digital Twin
- 2022
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 16:2, s. 2120-2132
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Tidskriftsartikel (refereegranskat)abstract
- The nanostructure, primarily particle orientation, controls mechanical and functional (e.g., mouthfeel, cell compatibility, optical, morphing) properties when macroscopic materials are assembled from nanofibrils. Understanding and controlling the nanostructure is therefore an important key for the continued development of nanotechnology. We merge recent developments in the assembly of biological nanofibrils, X-ray diffraction orientation measurements, and computational fluid dynamics of complex flows. The result is a digital twin, which reveals the complete particle orientation in complex and transient flow situations, in particular the local alignment and spatial variation of the orientation distributions of different length fractions, both along the process and over a specific cross section. The methodology forms a necessary foundation for analysis and optimization of assembly involving anisotropic particles. Furthermore, it provides a bridge between advanced in operandi measurements of nanostructures and phenomena such as transitions between liquid crystal states and in silico studies of particle interactions and agglomeration.
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| 44. |
- Gray, Victor, Dr, 1988-, et al.
(författare)
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Direct vs Delayed Triplet Energy Transfer from Organic Semiconductors to Quantum Dots and Implications for Luminescent Harvesting of Triplet Excitons
- 2020
-
Ingår i: ACS Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 14:4, s. 4224-4234
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid inorganic-organic materials such as quantum dots (QDs) coupled with organic semiconductors have a wide range of optoelectronic applications, taking advantage of the respective materials' strengths. A key area of investigation in such systems is the transfer of triplet exciton states to and from QDs, which has potential applications in the luminescent harvesting of triplet excitons generated by singlet fission, in photocatalysis and photochemical upconversion. While the transfer of energy from QDs to the triplet state of organic semiconductors has been intensely studied in recent years, the mechanism and materials parameters controlling the reverse process, triplet transfer to QDs, have not been well investigated. Here, through a combination of steady-state and time-resolved optical spectroscopy we study the mechanism and energetic dependence of triplet energy transfer from an organic ligand (TIPS-tetracene carboxylic acid) to PbS QDs. Over an energetic range spanning from exothermic (-0.3 eV) to endothermic (+0.1 eV) triplet energy transfer we find that the triplet energy transfer to the QD occurs through a single step process with a clear energy dependence that is consistent with an electron exchange mechanism as described by Marcus-Hush theory. In contrast, the reverse process, energy transfer from the QD to the triplet state of the ligand, does not show any energy dependence in the studied energy range; interestingly, a delayed formation of the triplet state occurs relative to the quantum dots' decay. Based on the energetic dependence of triplet energy transfer we also suggest design criteria for future materials systems where triplet excitons from organic semiconductors are harvested via QDs, for instance in light emitting structures or the harvesting of triplet excitons generated via singlet fission.
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| 45. |
- Grigorev, Vladimir, et al.
(författare)
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Optically Triggered Néel Vector Manipulation of a Metallic Antiferromagnet Mn2Au under Strain
- 2022
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 16:12, s. 20589-20597
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Tidskriftsartikel (refereegranskat)abstract
- The absence of stray fields, their insensitivity to external magnetic fields, and ultrafast dynamics make antiferromagnets promising candidates for active elements in spintronic devices. Here, we demonstrate manipulation of the Néel vector in the metallic collinear antiferromagnet Mn2Au by combining strain and femtosecond laser excitation. Applying tensile strain along either of the two in-plane easy axes and locally exciting the sample by a train of femtosecond pulses, we align the Néel vector along the direction controlled by the applied strain. The dependence on the laser fluence and strain suggests the alignment is a result of optically triggered depinning of 90° domain walls and their motion in the direction of the free energy gradient, governed by the magneto-elastic coupling. The resulting, switchable state is stable at room temperature and insensitive to magnetic fields. Such an approach may provide ways to realize robust high-density memory device with switching time scales in the picosecond range.
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| 46. |
- Guan, Tianfu, et al.
(författare)
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Decoding the Self-Assembly Plasmonic Interface Structure in a PbS Colloidal Quantum Dot Solid for a Photodetector
- 2023
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 17:22, s. 23010-23019
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid plasmonic nanostructures have gained enormous attention in a variety of optoelectronic devices due to their surface plasmon resonance properties. Self-assembled hybrid metal/quantum dot (QD) architectures offer a means of coupling the properties of plasmonics and QDs to photodetectors, thereby modifying their functionality. The arrangement and localization of hybrid nanostructures have an impact on exciton trapping and light harvesting. Here, we present a hybrid structure consisting of self-assembled gold nanospheres (Au NSs) embedded in a solid matrix of PbS QDs for mapping the interface structures and the motion of charge carriers. Grazing-incidence small-angle X-ray scattering is utilized to analyze the localization and spacing of the Au NSs within the hybrid structure. Furthermore, by correlating the morphology of the Au NSs in the hybrid structure with the corresponding differences observed in the performance of photodetectors, we are able to determine the impact of interface charge carrier dynamics in the coupling structure. From the perspective of architecture, our study provides insights into the performance improvement of optoelectronic devices.
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| 47. |
- Gupta, G., et al.
(författare)
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Exploiting Mass Spectrometry to Unlock the Mechanism of Nanoparticle-Induced Inflammasome Activation
- 2023
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Ingår i: Acs Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 17:17, s. 17451-17467
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Tidskriftsartikel (refereegranskat)abstract
- Nanoparticles (NPs) elicit sterile inflammation, but the underlying signaling pathways are poorly understood. Here, we report that human monocytes are particularly vulnerable to amorphous silica NPs, as evidenced by single-cell-based analysis of peripheral blood mononuclear cells using cytometry by time-of-flight (CyToF), while silane modification of the NPs mitigated their toxicity. Using human THP-1 cells as a model, we observed cellular internalization of silica NPs by nanoscale secondary ion mass spectrometry (nanoSIMS) and this was confirmed by transmission electron microscopy. Lipid droplet accumulation was also noted in the exposed cells. Furthermore, time-of-flight secondary ion mass spectrometry (ToF-SIMS) revealed specific changes in plasma membrane lipids, including phosphatidylcholine (PC) in silica NP-exposed cells, and subsequent studies suggested that lysophosphatidylcholine (LPC) acts as a cell autonomous signal for inflammasome activation in the absence of priming with a microbial ligand. Moreover, we found that silica NPs elicited NLRP3 inflammasome activation in monocytes, whereas cell death transpired through a non-apoptotic, lipid peroxidation-dependent mechanism. Together, these data further our understanding of the mechanism of sterile inflammation.
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| 48. |
- Hartl, Tobias, et al.
(författare)
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Cluster Superlattice Membranes
- 2020
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 14:10, s. 13629-13637
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Tidskriftsartikel (refereegranskat)abstract
- Cluster superlattice membranes consist of a two-dimensional hexagonal lattice of similar-sized nanoclusters sandwiched between single-crystal graphene and an amorphous carbon matrix. The fabrication process involves three main steps, the templated self-organization of a metal cluster superlattice on epitaxial graphene on Ir(111), conformal embedding in an amorphous carbon matrix, and subsequent lift-off from the Ir(111) substrate. The mechanical stability provided by the carbon-graphene matrix makes the membrane stable as a free-standing material and enables transfer to other substrates. The fabrication procedure can be applied to a wide variety of cluster materials and cluster sizes from the single-atom limit to clusters of a few hundred atoms, as well as other two-dimensional layer/host matrix combinations. The versatility of the membrane composition, its mechanical stability, and the simplicity of the transfer procedure make cluster superlattice membranes a promising material in catalysis, magnetism, energy conversion, and optoelectronics.
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| 49. |
- Hochstetter, Axel, et al.
(författare)
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Deterministic Lateral Displacement : Challenges and Perspectives
- 2020
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 14:9, s. 10784-10795
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Forskningsöversikt (refereegranskat)abstract
- The advent of microfluidics in the 1990s promised a revolution in multiple industries from healthcare to chemical processing. Deterministic lateral displacement (DLD) is a continuous-flow microfluidic particle separation method discovered in 2004 that has been applied successfully and widely to the separation of blood cells, yeast, spores, bacteria, viruses, DNA, droplets, and more. Deterministic lateral displacement is conceptually simple and can deliver consistent performance over a wide range of flow rates and particle concentrations. Despite wide use and in-depth study, DLD has not yet been fully elucidated or optimized, with different approaches to the same problem yielding varying results. We endeavor here to provide up-to-date expert opinion on the state-of-art and current fundamental, practical, and commercial challenges with DLD as well as describe experimental and modeling opportunities. Because these challenges and opportunities arise from constraints on hydrodynamics, fabrication, and operation at the micro- and nanoscale, we expect this Perspective to serve as a guide for the broader micro- and nanofluidic community to identify and to address open questions in the field.
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| 50. |
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