Small Nanoparticles Research Articles

Glycan-Silica Nanoparticles as Effective Inhibitors for Blocking Virus Infection.

Small solid silica nanoparticles (SiNPs) have been used for multivalent carbohydrate presentation in DC-/L-SIGN-mediated viral infection models. Glycosylated SiNPs (glycoSiNPs) were fully characterized by different experimental techniques, including NMR, DLS, TGA, FTIR, and XPS, which confirmed their chemical structures. As a proof-of-concept, the capacity of glycoSiNPs to interact with Concanavalin A (ConA), a model lectin, using DLS binding experiments and UV-vis turbidimetry assays was analyzed. Their antiviral activity was assessed in a cellular assay using an artificial Ebola virus, demonstrating the potent inhibition of DC-SIGN-mediated infection. Notably, glycoSiNPs functionalized with a trivalent Manα1,2Man glycodendron exhibited the strongest inhibitory activity, with an IC50 of 135 ng/mL and a 170-fold lower efficiency in blocking L-SIGN-mediated viral infection. These findings suggest that glycoSiNPs present a promising approach for developing antiviral agents that selectively target the DC-SIGN pathway over the L-SIGN one.

Charge-Ordering and Magnetic Transitions in Nanocrystalline Half-Doped Rare Earth Manganite Ho0.5Ca0.5MnO3

This work investigates nanostructured Ho0.5Ca0.5MnO3, considered a model system of the Ln0.5Ca0.5MnO3 series of manganites with perovskite structures featuring small lanthanide (Ln) ions half-substituted by Ca ions. Here, we propose a modified hybrid sol–gel–solid-state approach to produce multiple samples with a single batch, obtaining very high crystalline quality and ensuring the same chemical composition, with an average particle size in the range 39–135 nm modulated on-demand by a controlled calcination process. Our findings evidence that, provided the crystalline structure is preserved, the charge-ordering transition can be observed even at the nanoscale. Additionally, this research explores the presence of glassy phenomena, which are commonly seen in this class of materials, to enhance our understanding beyond simplistic qualitative observations. Comprehensive characterization using DC and AC magnetometry, along with relaxation and aging measurements, reveals that the complex dynamics typical of glassy phenomena emerge only at the nanoscale and are not visible in the bulk counterpart. Nevertheless, the analysis confirms that even the sample with the smallest nanoparticles cannot be intrinsically classified as canonical spin glass.

Noninvasive Detection of Chorioretinal Hypoxia via Poly(lactic‐co‐glycolic acid) Nanoparticles Embedded with Purely Organic Phosphors

Ischemia‐induced hypoxia is a critical complication in retinal diseases, leading to significant vision impairment and blindness due to disrupted blood flow and oxygen delivery. Currently, there is no effective method to assess oxygen levels in extravascular retinal tissue. Traditional hypoxia detection methods, such as oxygen‐sensitive microelectrodes, magnetic resonance imaging, and retinal oximetry, have limitations including invasiveness, low spatial resolution, and lack of real‐time monitoring. Herein, a noninvasive hypoxia detection method is proposed by utilizing lipid‐polymer nanoparticles (NPs) with purely organic room‐temperature phosphorescence materials for real‐time detection with high spatial and temporal resolution. To enhance biocompatibility and efficacy, NPs were fabricated using biodegradable poly(lactic‐co‐glycolic acid) (PLGA) and SeCO as a phosphor. PLGA degrades into nontoxic by‐products, while the excitation wavelength of SeCO at 393 nm minimizes damage from short wavelengths and enhances tissue penetration. Furthermore, the NPs’ size is optimized to improve cellular uptake and reduce bodily accumulation, as smaller NPs are preferred for biocompatibility. Herein, synthesis, characterization, and evaluation of these PLGA‐based phosphorescent NPs in rabbit models of retinal vein occlusion and choroidal vascular occlusion are involved. This approach represents a significant advancement in noninvasive biomedical imaging, improving the diagnosis and management of ischemic retinal diseases.

Effect of Particle Size and Alloying with Gallium and Zinc in Copper Nanoparticles from Ab Initio Molecular Dynamics

Supported nanoparticles (NPs) are an intense field of research in industry and academia due to their unique catalytic properties. Yet, establishing relationships between structure and activity is challenging due to multiple possible compositions, interfaces, and alloy formation. This is especially pronounced for bimetallic NPs used in the CO2‐hydrogenation‐to‐methanol, where the structure responds dynamically to the chemical potential of the reactants and products, resulting in distinct surface structures depending on the exact reaction conditions. These phenomena have been highlighted by combining ab initio Molecular Dynamics (AIMD) and Metadynamics (MTD) with in situ X‐ray absorption spectroscopy, chemisorption, and CO‐IR. Here, we aim to understand how particle size and simulation temperature influence the structure and dynamics of small Cu NPs using the diffusion coefficients and the radial distribution function/atomic pair density function as descriptors using AIMD simulations. We found that decreasing the particle size or increasing the simulation temperature results in increased atom mobility, highlighted by the increased metal diffusion and resulting in reduced particle crystallinity. We also find that alloying Cu with Ga significantly increases the diffusion of both elements in the particle compared to the monometallic ones, while such diffusion lies in between the individual elements composing the CuZn particles.

Molecular mechanisms behind the anti corona virus activity of small metal oxide nanoparticles.

The recent COVID-19 pandemic has set a strong quest for advanced understanding of possible tracks in abating and eliminating viral infections. In the view that several families of "pristine" small oxide nanoparticles (NPs) have demonstrated viricidal activity against SARS-CoV-2, we studied the effect of two NPs, with presumably different reactivity, on two viruses aiming to evaluate two "primary suspect" routes of their antiviral activity, either specific blocking of surface proteins or causing membrane disruption. The chosen NPs were non-photoactive 3.5 nm triethanolamine terminated (surface capped) titania TiO2 NPs (TATT) and ultrasmall (1.1 nm) silicotungstate polyoxometalate (POM) NPs. The former were expected to both, interact with viral surface proteins as well as strongly complex with phosphate groups whereas the latter was not expected to form surface complexes. We demonstrated that expectedly, POM NPs up to 1.25 mM (4.5 mg l-1) had no significant antiviral activity towards neither of the used viruses, an enveloped transmissible gastroenteritis virus (TGEV) belonging to coronaviruses and non-enveloped encelomyocarditis virus (EMCV). At the same time, TATT NPs exhibited statistically significant (p < 0.05) antiviral activity against TGEV starting from 0.125 mM (12 μg ml-1). However, no antiviral activity of TATT against non-enveloped EMCV was detected. The observation that TATT NPs showed activity only against enveloped viruses and at relatively high concentrations suggests that the effect could be related with complexation with phospholipids. Possible chemical mechanism of viral membrane disruption was investigated by a variable temperature NMR study of NP complexation with model organic phosphate molecules, proving TATT to strongly interact with them and POM remain unreacted. Viral membrane disruption by TATT NPs was additionally confirmed by demonstraing RNA leackage from TGEV upon contact with those NPs. Therefore, our study proved a new mechanism of antiviral action of titania NPs in the dark which involved membrane disruption proceeding via direct surface complexation.

Confined Growth by Self-Combustion of a Cu-Based Nanophase into Mesostructured Acid Supports for DME Production from CO2.

This work deals with the design of nanocomposite hydrogenation-dehydration bifunctional catalysts for the one-pot conversion of CO2 to dimethyl ether (DME), focusing on obtaining a high and homogeneous dispersion of a Cu-based CO2 hydrogenation phase into the pores of mesostructured supports. Particularly, three aluminosilicate mesostructured acid catalysts with catalytic activity towards methanol dehydration and featuring different porous structures (Al-MCM-41, Al-SBA-15, Al-SBA-16) were synthesized and used as supports to host a CuO/ZnO/ZrO2 (CZZ) CO2 hydrogenation catalyst for methanol synthesis. The use of a mesostructured support allows to maximize the exposed surface of the CO2 reduction function by nanostructuring it through its confinement within the mesochannels, thus obtaining nanocomposite bifunctional catalysts with an ultra-small hydrogenation nanophase. The nanocomposites were obtained using an impregnation strategy combined with a self-combustion reaction, allowing to incorporate the CO2 reduction phase inside the mesopores. In all cases, the characterization shows that the hydrogenation phase species are highly and homogeneously dispersed into the supports as either small nanoparticles or as a nanolayer. The as-obtained nanocomposites were tested for their catalytic activity and the results discussed taking into account the structural, textural, and acidic properties of the supports and nanocomposites.

P0025 The effect of very small superparamagnetic nanoparticles on human blood cells as a diagnostic tool in Inflammatory Bowel Disease

Abstract Background The field of application of organic or inorganic nanoparticles (1-100 nm size) is extensive and involves their use in medicine. This includes using nanoparticles in human beings or animals (life-stock) which holds advantages but also bears risks. Therefore, nanoparticles used in diagnostics and therapy should be inert not affecting tissues or immune cells. Additionally, nanoparticles should not aggregate to form clusters exceeding the size of 100 nm or accumulate in sensitive structures like bone marrow or brain for long-term deposition. We developed in-house very small superparamagnetic iron oxide nanoparticles (VSOP) with a size of 7 nm that were successfully used in preclinical magnetic resonance imaging (MRI) for the detection of intestinal inflammation and sclerosis. This study elucidates the effect of nanoparticles on human blood cells, including monocytes as well as monocyte-derived macrophages, in vitro as a first step toward clinical application in inflammatory bowel disease (IBD). Methods Whole blood of healthy donors and patients suffering from IBD as well as monocytes and monocyte-derived macrophages were treated with VSOP in vitro and analysed for changes in their transcriptome, phenotype and function. For transcriptome analysis, RNA sequencing was performed. Cell abundance, activation and proliferation were measured by mass cytometry. Migratory behavior of monocytes was analyzed by live microscopy. Cell metabolism was detected by Seahorse assay. Results RNA sequencing of monocytes showed that the most significantly regulated gene is encoding for the transferrin receptor (Tcfr). As a response to VSOP treatment and VSOP uptake thereby increasing the levels of intracellular iron, Tcfr is probably downregulated to restrict further iron uptake. While RNA sequencing of whole blood showed only significant differences in non-coding genes (C3orf86P, ENSG00000278996, ENSG00000259002), CyTOF analyses revealed that VSOP-treated monocytes are neither activated nor showing increased proliferation. Also, the migratory behavior is not influenced by VSOP uptake. Additionally, VSOP uptake resulted in an enhanced oxygen consumption rate and extracellular acidification rate. In comparison to the uptake of Latex beads, these increased rates are rather attributed to phagocytosis. Conclusion Analyses of our data with PBMC, monocytes and monocyte-derived macrophages suggest, that treatment with VSOP has no major affect on phenotype and function of immune cells. Therefore, VSOP are a promising tool for the early detection of IBD through MRI.

An Icosahedral 55-Atom Iron Hydride Cluster Protected by Tri-tert-butylphosphines.

Nanoclusters are nanometer-sized molecular compounds characterized by significant metal-metal bonding and low average oxidation states, and they exhibit unique properties distinct from those of small metal complexes or nanoparticles. Unlike noble metals stable in metallic forms, the synthesis of nanometer-sized iron clusters has been precluded by the relatively weak iron-iron bonds and the high reactivity of low oxidation state iron, despite the extensive history of molecular iron compounds. Here, we report the synthesis and characterization of a cationic 55-atom iron cluster with a 1.2 nm icosahedral core. Its 12 vertices are occupied by tri-tert-butylphosphines, while multiple hydrides cover the surface. This core can be viewed as a substructure of the face-centered cubic (fcc), in contrast to the body-centered cubic (bcc) for the stable bulk phase. This work reveals a stable structure and fundamental properties of a nanometer-sized iron cluster, which have remained elusive for decades, and the simple synthetic protocol provides a route to explore molecular nanochemistry.

The Impact of Nanoparticles and Molecular Forms of TiO2 on the Rhizosphere of Plants in the Example of Common Wheat (Triticum aestivum L.)-Shifts in Microbiome Structure and Predicted Microbial Metabolic Functions.

This study investigated the effects of various titanium nanoparticles (TiO2NPs) on the structure, function, and trophic levels of the wheat rhizobiome. In contrast to the typically toxic effects of small nanoparticles (~10 nm), this research focused on molecular TiO2 and larger nanoparticles, as follows: medium-sized (68 nm, NPs1) and large (>100 nm, NPs2). The results demonstrated significant yet diverse impacts of different TiO2 forms on the rhizosphere microbiota. Large TiO2NPs2 and molecular TiO2 adversely affected the bacteriobiome and mycobiome, leading to an increase in autotrophic microbial groups. In contrast, medium-sized TiO2NPs1 shifted the microbiome toward chemoheterotrophy, promoting plant growth-associated bacteria, fungal saprotrophs, and potential phytopathogens, suggesting a beneficial r-strategy within the rhizosphere. Other treatments induced oligotrophic conditions, resulting in a less flexible rhizobiome with diminished root associations but an increased abundance of Trichoderma spp. Structural modelling revealed that even minor changes in operational taxonomic units (OTUs) could significantly alter the microbiota's metabolic potential. These findings highlight the importance of further research to optimize nanoparticle applications for sustainable agriculture.

Well-Defined PtCo@Pt Core-Shell Nanodendrite Electrocatalyst for Highly Durable Oxygen Reduction Reaction.

The rational design of efficient electrocatalysts with controllable structure and composition is crucial for enhancing the lifetime and cost-effectiveness of oxygen reduction reaction (ORR). PtCo nanocrystals have gained attention due to their exceptional activity, yet suffer from stability issues in acidic media. Herein, an active and highly stable electrocatalyst is developed, namely 3D Pt7Co3@Pt core-shell nanodendrites (NDs), which are formed through the self-assembly of small Pt nanoparticles (≈6nm). This unique structure significantly improves the ORR with an enhanced mass activity (MA) of 0.54 A mgPt -1, surpassing that of the commercial Pt/C (com-Pt/C) catalyst by three fold (0.17 A mgPt -1). The well-organized dendritic morphology, along with the Pt-rich shell, contributes significantly to the observed high catalytic activity and superior stability for acidic ORR, which exhibit a loss of 2.1% in MA and, impressively, an increase of 12.0% in specific activity (SA) after an accelerated durability test (ADT) of 40,000 potential-scanning cycles. This work offers insights for improving the design of highly stable Pt-based electrocatalysts for acidic ORR.

Optimized Synthesis and Stabilization of Superparamagnetic Iron Oxide Nanoparticles for Enhanced Biomolecule Adsorption.

Monodisperse and colloidally stable magnetic iron oxide nanoparticles have been developed for diverse biotechnology applications. Although promising for the adsorption of organic molecules, the low density of adsorption sites in these nanoparticles has been a significant challenge. In this study, an optimized factorial design with response surface methodology (RSM) was employed to produce small Superparamagnetic Iron Oxide Nanoparticles (SPIONs) stabilized with tetraethoxysilane (TEOS). Bovine Serum Albumin (BSA) was selected for immobilization on the surface of SPIONs to test adsorption capacity. The model was validated by correlating significant factors with experimental responses, enabling the prediction of the smallest nanoparticle size. We obtained superparamagnetic SPIONs (75.12 emu/g) with high surface area and an average diameter of 11.06 ± 0.84 nm, with stability improved by the adsorption of TEOS (-46.24 mV) and suitable for pH values from 2 to 10 and salt concentrations up to 1 M. The maximum adsorption capacity of the nanoparticles was 87.8 ± 1.79 mg of BSA per gram of nanoparticles. The nanomaterial synthesized here presents a favorable platform for anchoring protein molecules via silanol groups on its electrostatically charged surface. This study introduces an effective strategy for the synthesis and stabilization of SPIONs with potential biotechnology applications.

Thermodynamics and models for small nanoparticles upon protein adsorption.

Proteins are some of the most important components in living organisms. When nanoparticles enter a living system, they swiftly interact with proteins to produce the so-called "protein corona", which depicts the adsorption of proteins on large nanoparticles (normally tens to hundreds of nanometers). However, the sizes of small nanoparticles (typically, fluorescent nanomaterials such as quantum dots, noble metal nanoclusters, carbon dots, etc.) are less than 10 nm, which are comparable or even much smaller than those of proteins. Can proteins also adsorb onto the surface of small nanoparticles to form a "protein corona"? In this perspective, the interactions between small nanoparticles with proteins are discussed in detail, including the main characterization methods and thermodynamic mechanisms. The interaction models are summarized. In particular, the concept of a "protein complex" is emphasized.

Bright "D-A-D" semiconducting small molecule aggregates for NIR-II fluorescence bioimaging guiding photothermal therapy.

Donor-acceptor-donor (D-A-D) semiconducting small molecule nanoparticles have emerged as high-performance NIR-II fluorophores for real-time bioimaging. However, due to their intrinsic defects in aggregation-caused quenching (ACQ) and "energy gap law", D-A-D semiconducting small molecule nanoparticles typically exhibit low NIR-II fluorescence quantum yields (QYs). Herein, both the strategies of aggregation induced emission (AIE) and intermolecular charge transfer (CT) have been incorporated into the design of new D-A-D semiconducting small molecules. AIE enhances the NIR-II fluorescence intensity of NIR-II fluorophore aggregates in nanoparticles, while intermolecular CT increases both NIR absorption and NIR-II emission, thereby further improving their NIR-II fluorescence QYs. Four D-A-D semiconducting small molecules (TD, TT, TC, and TCD) were designed. Due to the combination of intermolecular CT and AIE of TCD aggregates, the NIR absorption and NIR-II fluorescence signals of TCD NPs were stronger than those of TD NPs and TT NPs with a single AIE property or TC NPs with strong intermolecular CT. Furthermore, TCD NPs demonstrated excellent performance in in vivo NIR-II fluorescence bioimaging guiding photothermal therapy.

Tailoring Mechanical Performance in Bulk Nanoparticle-Structured ZnO and Al₂O₃: Insights from Deep Learning Potential Molecular Dynamics Simulations

The rapid advancements in nanotechnology have created unique opportunities to manipulate material properties at the nanoscale, particularly through the design of nanoparticle-structured (NP-structured) materials. Due to their distinctive mechanical and chemical properties, materials composed of nanoparticles, such as ZnO and Al₂O₃, are of high interest for applications in structural reinforcements, electronics, and catalysis. However, accurately predicting the mechanical behavior of NP-structured materials remains a challenge. This study investigates the mechanical properties of bulk nanoparticle-structured (NP-structured) materials composed of ZnO and Al₂O₃ nanoparticles in FCC and BCC configurations. We used deep learning potentials (DLPs) derived from density functional theory (DFT) calculations to comprehensively analyze stress-strain behavior, local shear strain distributions, and elastic properties across various nanoparticle sizes and compositions. Our findings reveal that nanoparticle size and crystalline arrangement are crucial in determining the mechanical performance of these materials. Smaller ZnO nanoparticles exhibit higher yield stress, ultimate stress, and Young's modulus in both FCC and BCC configurations, attributed to their higher surface-to-volume (S/V) ratio. In contrast, larger Al₂O₃ nanoparticles demonstrated superior mechanical properties, especially in FCC configurations, due to the strong ionic bonding and effective stress distribution inherent in Al₂O₃. In ZnO/Al₂O₃ composite systems, we found that the mechanical properties could be precisely tuned by adjusting the nanoparticle size and ratio. Larger nanoparticles in FCC arrangements contributed to higher yield stress and stiffness, while smaller nanoparticles in BCC arrangements provided better overall mechanical performance. This work highlights the potential of DLPs in accurately predicting and optimizing the mechanical properties of NP-structured materials, offering valuable insights for the design of advanced materials with tailored mechanical characteristics.

Carbon dots from surface-capping/passivation of small carbon nanoparticles with nanoscale titanium dioxide

Carbon dots from surface-capping/passivation of small carbon nanoparticles with nanoscale titanium dioxide

Determination of absolute intramolecular distances in proteins using anomalous X-ray scattering interferometry.

Biomolecular structures are typically determined using frozen or crystalline samples. Measurement of intramolecular distances in solution can provide additional insights into conformational heterogeneity and dynamics of biological macromolecules and their complexes. The established molecular ruler techniques used for this (NMR, FRET, and EPR) are, however, limited in their dynamic range and require model assumptions to determine absolute distance or distance distributions. Here, we introduce anomalous X-ray scattering interferometry (AXSI) for intramolecular distance measurements in proteins, which are labeled at two sites with small gold nanoparticles of 0.7 nm radius. We apply AXSI to two different cysteine-variants of maltose binding protein in the presence and absence of its ligand maltose and find distances in quantitative agreement with single-molecule FRET experiments. Our study shows that AXSI enables determination of intramolecular distance distributions under virtually arbitrary solution conditions and we anticipate its broad use to characterize protein conformational ensembles and dynamics.

Hierarchical mesoporous Mn2O3/NiO/Co3O4 nanocubes derived from Prussian blue analogues for high performance asymmetric supercapacitor

In this paper, a hierarchical Mn2O3/NiO/Co3O4 (denoted as MNC) composite nanocubes composed of small nanoparticles were obtained by calcinating Prussian blue analogues (PBAs) nanocubes precursor. The effects of heating temperature...

Constructing Chiral Core–Shell–Satellite Superstructures for Highly Efficient Antenna–Reactor Hot Electron Generation

AbstractIn hot electron (HE)‐driven photocatalysis, plasmonic metal nanocrystals with small size, or even nanoclusters, are preferrable. Antenna–reactor mechanism has been utilized to further boost the photocatalytic performance of the small reactor nanoparticles. The construction of a metal–semiconductor–metal core–shell–satellite (CSS) superstructure is demonstrated for highly efficient HE generation of the entire CSS architecture, where a mesoporous TiO2 (mTiO2) shell spatially separates the Au nanohelicoid (AuNH) antenna core and Au nanocluster (AuNC) reactor satellites. Individual AuNH@mTiO2@AuNC CSS superstructures are optically characterized using dark field scattering and circular differential scattering spectroscopies. The HE and circular differential HE photocurrent responses of the CSS superstructures are measured using a photoelectrochemical cell, where 12.4‐ and 8.3‐fold enhancements are respectively achieved with respect to that of the AuNHs. Electromagnetic simulations reveal that the contribution from the satellites with a small accumulative volume is almost equal to that from the core. Therefore, the specific‐volume HE rate of the satellites exhibit a high amplification ratio, 350, with respect to that of the core, being attributed to the antenna–reactor mechanism in the CSS architecture. Key factors are optimized, which includes small size of the plasmonic satellites, E‐field enhancement, and mesoporous semiconductor shell for efficient separation and collection of hot carriers.

Carbon Dots from Pre‐Existing Nanoparticles Versus Carbonization: Similarity and Difference in Sample Structure‐Morphology with Property and Mechanistic Consequences

Carbon dots (CDots) are classically synthesized by organic functionalization of pre‐existing small carbon nanoparticles, but most of the dot samples reported in the literature are prepared by thermal carbonization processing of selected organic precursors. Highlighted and discussed in this article are the necessity of using proper thermal processing conditions for the carbonization produced samples to be CDots like, the similarities and differences in sample structure and morphology between the two kinds of dot samples, and their associated property and mechanistic consequences.

High-Sensitivity Detection of Chiro-Optical Effects in Single Nanoparticles by Four-Wave Mixing Interferometry.

The field of chiral nanoparticles is rapidly expanding, yet measuring the chirality of single nano-objects remains a challenging endeavor. Here, we report a technique to detect chiro-optical effects in single plasmonic nanoparticles by means of phase-sensitive polarization-resolved four-wave mixing interferometric microscopy. Beyond conventional circular dichroism, the method is sensitive to the particle polarizability, in amplitude and phase. First, we demonstrate its application on single chiral nanohelices fabricated by focused ion beam induced deposition. We examined the combination of detected fields, which measures the particle polarizability, and showed that this is a sensitive reporter of chirality, providing dissymmetry factors (g α) impressively approaching unity. We then applied the method to a set of individual small gold nanoparticles near the dipole limit (60 nm nominal size), having correspondingly small chiral effects from the intrinsic lattice defects and nonperfectly spherical shape. We find that g α is randomly distributed in the population, consistent with its nondeterministic origin, but again exhibits remarkably high values, an order of magnitude higher than those obtained using conventional light absorption. Considering the importance of chiral plasmonic nanoparticles in fields ranging from catalysis to metamaterials, this technique offers a powerful way to quantify chiro-optical effects at the single particle level with unprecedented sensitivity.