Attachment Of Particles Research Articles

Particle Attachment Growth of Au@Ag Core–Shell Nanocuboids

In the templated synthesis of colloidal core-shell nanoparticles, the monomer attachment growth mechanism has been widely accepted to describe the growth process of shells. In this work, by using advanced transmission electron microscope techniques, we directly observe two alternative particle attachment growth pathways that dominate the growth of Au@Ag core-shell nanocuboids. One pathway involves the in situ reduction of AgCl nanoparticles attached to Au nanorods and the subsequent epitaxial growth of the Ag shell. The other pathway involves the adherence of Ag-AgCl Janus nanoparticles to Au nanorods with random orientations, followed by nanoparticle redispersion and the resulting formation of epitaxial Ag shells on the Au nanorods. The particle-mediated growth of Ag shells is accompanied by the redispersion of surface atoms, tending to form a uniform structure. The validation of the particle attachment growth processes at the atomic scale provides a new mechanistic understanding of core-shell nanostructure synthesis.

Growth dynamics and amorphous-to-crystalline phase transformation in natural nacre

Biominerals, such as nacreous bivalve shells, are important archives of environmental information. Most marine calcifiers form their shells from amorphous calcium carbonate, hypothesised to occur via particle attachment and stepwise crystallisation of metastable precursor phases. However, the mechanism of this transformation, including the incorporation of trace elements used for environmental reconstructions, are poorly constrained. Here, using shells of the Mediterranean mussel, we explore the formation of nacre from the meso- to the atomic scale. We use a combination of strontium pulse-chase labelling experiments in aquaculture and correlated micro- to sub-nanoscale analysis to show that nacre grows in a dynamic two-step process with extensional and space-filling growth components. Furthermore, we show that nacre crystallizes via localised dissolution and reprecipitation within nanogranules. Our findings elucidate how stepwise crystallization pathways affect trace element incorporation in natural biominerals, while preserving their intricate hierarchical ultrastructure.

Physicochemical characterization of reusable facemasks and theoretical adhesion by a challenged bacterium.

Adhesion of microorganisms on facemask surfaces is a major problem that produces contamination of the mask wearer either by inhalation or by direct contact. Generally, physicochemical properties of the material and the microorganism are responsible for this adhesion and are also reported to influence the filtration efficiency of facemasks. However, theses surface proprieties and their effect on particles attachment on facemask materials remain poorly documented. The purpose of this study was to investigate the physicochemical properties of seven facemasks and evaluate the influence of these characteristics on the adhesion of Sataphylococcus aureus. Physicochemical properties is done by contact angle method and scanning electron microscopy while theoretical adhesion of S. aureus is done according to XDLVO approach. The obtained results showed that all masks have a hydrophobic character. The electron donor and electron acceptor parameters change depending on each mask. Chemical analysis demonstrates the presence of two chemical elements (carbon and oxygen). Predictive adhesion demonstrate that S. aureus has an attractive behavior towards the masks used but the potential of adhesion is not the same. Such information is valuable to understand attachment of biological particles and to contribute in the inhibition of this attachment.

A temporally relaxed theory of physically or chemically non-equilibrium solute transport in heterogeneous porous media

Groundwater constitutes a critical component in providing fresh water for various human endeavors. Nevertheless, its susceptibility to contamination by pollutants represents a significant challenge. A comprehensive understanding of the dynamics of solute transport in groundwater and soils is essential for predicting the spatial and temporal distribution of these contaminants. Presently, conventional models such as the mobile–immobile (MIM) model and the rate-limited sorption (RLS) model are widely employed to describe the non-Fickian behavior of solute transport. In this research, we present a novel approach to solute transport that is founded on the temporally relaxed theory of Fick’s Law. Our methodology introduces two relaxation times to account for solute particle collisions and attachment, leading to the derivation of a new advection–dispersion equation. Our findings indicate that the relaxation times possess similar properties to the transport parameters in the MIM and RLS models, and our solution can be applied to accurately predict transport parameters from soil column experiments. Additionally, we discovered that the relaxation times are proportional to the magnitude of Peclet number. This innovative approach provides a deeper insight into solute transport and its impact on groundwater contamination.

Structural incorporation of iron influences biomethylation potential of mercury sulfide

Mercury and ferrous iron commonly co-exist in anaerobic environments, the hotspots of microbial mercury methylation that leads to formation of neurotoxic methylmercury. However, the influence of ferrous iron on mercury bioavailability and methylation remains unclear. Here, we discover that microbial methylmercury production is inhibited by iron addition in a non-monotonical manner, reaching the minimal level at the initial molar ratio of dissolved Fe/Hg as 1/3, when highly aggregated Hg–S–Fe nanoparticles occur and prevent the nanoparticle–bacteria interactions. The dominant mercury species formed upon Hg–S–Fe co-precipitation is iron-incorporated nano-metacinnabar with short-range structural disorder. The methylation potential of this mercury species is inversely correlated with the aggregation state of nanoparticles. The non-monotonical trends of the aggregation state and subsequent methylation of nano-metacinnabar are due to the opposite effects of ferrous iron on the nucleation and particle attachment that determine the formation of nanoparticle aggregates. Increased Fe/Hg ratio hinders particle nucleation and thus decreases the density of particle monomers for aggregation. However, Fe substitution of sub-surface Hg weakens the inner-sphere coordination of surface Hg with natural thiol ligands and consequently enhances nano-metacinnabar aggregation. This new mechanistic insight is important for assessing and minimizing the risks of mercury methylation, and informs how intertwined iron and sulfur cycling may influence metal bioavailability in the changing environment.

Amentoflavone inhibits hepatitis B virus infection via the suppression of preS1 binding to host cells.

Hepatitis B virus (HBV) is a leading cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Current therapeutic drugs for chronic HBV infection use IFN and nucleos(t)ide analogs; however, their efficacy is limited. Thus, there is an urgent need to develop new antivirals for HBV therapy. In this study, we identified a plant-derived polyphenolic bioflavonoid, amentoflavone, as a new anti-HBV compound. Amentoflavone treatment dose-dependently inhibited HBV infection in HBV-susceptible cells with HepG2-hNTCP-C4 and primary human hepatocyte PXB-cells. A mode-of-action study showed that amentoflavone inhibits the viral entry step, but not the viral internalization and early replication processes. Attachment of HBV particles as well as HBV preS1 peptide to HepG2-hNTCP-C4 cells was inhibited by amentoflavone. The transporter assay revealed that amentoflavone partly inhibits uptake of sodium taurocholate cotransporting polypeptide (NTCP)-mediated bile acid. Furthermore, effect of various amentoflavone analogs on HBs and HBe production from HBV-infected HepG2-hNTCP-C4 cells was examined. Robustaflavone exhibited comparable anti-HBV activity to that of amentoflavone and an amentoflavone-7,4', 4‴-trimethyl ether derivative (sciadopitysin) with moderate anti-HBV activity. Cupressuflavone or the monomeric flavonoid apigenin did not exhibit the antiviral activity. Amentoflavone and its structurally related biflavonoids may provide a potential drug scaffold in the design of a new anti-HBV drug inhibitor targeting NTCP.

The effect of high-frequency acoustic wave vibration pattern on HKUST’s multi-level pore structure

The physical properties of materials are critical to their functionality, and the ability to control these properties using external forces is a significant challenge. In this study, we investigate the effect of three high frequency acoustic wave vibration patterns on the structure and morphology of MOF particles. Our results indicate that while regular vibration patterns generated by SAW can alter particle morphology, hybrid waves and Lamb waves with irregular vibration patterns can synthesise MOF crystals with multi-level pores. The vibration pattern of acoustic waves is shown to be a critical factor in controlling the particle morphology process. These results provide new insights into the precise control of crystal structure and the theory of crystallisation by particle attachment (CPA).

Growth Process of Two-Dimensional Metal–Organic Framework Cu-BDC: A Particle Attachment Crystallization Mechanism Revealed by Microdroplet Flow Reaction

Growth Process of Two-Dimensional Metal–Organic Framework Cu-BDC: A Particle Attachment Crystallization Mechanism Revealed by Microdroplet Flow Reaction

In Situ Observations Reveal the Five-fold Twin-Involved Growth of Gold Nanorods by Particle Attachment.

Crystallization plays a critical role in determining crystal size, purity and morphology. Therefore, uncovering the growth dynamics of nanoparticles (NPs) atomically is important for the controllable fabrication of nanocrystals with desired geometry and properties. Herein, we conducted in situ atomic-scale observations on the growth of Au nanorods (NRs) by particle attachment within an aberration-corrected transmission electron microscope (AC-TEM). The results show that the attachment of spherical colloidal Au NPs with a size of about 10 nm involves the formation and growth of neck-like (NL) structures, followed by five-fold twin intermediate states and total atomic rearrangement. The statistical analyses show that the length and diameter of Au NRs can be well regulated by the number of tip-to-tip Au NPs and the size of colloidal Au NPs, respectively. The results highlight five-fold twin-involved particle attachment in spherical Au NPs with a size of 3-14 nm, and provide insights into the fabrication of Au NRs using irradiation chemistry.

Nanoparticle Assembly and Oriented Attachment: Correlating Controlling Factors to the Resulting Structures.

Nanoparticle assembly and attachment are common pathways of crystal growth by which particles organize into larger scale materials with hierarchical structure and long-range order. In particular, oriented attachment (OA), which is a special type of particle assembly, has attracted great attention in recent years because of the wide range of material structures that result from this process, such as one-dimensional (1D) nanowires, two-dimensional (2D) sheets, three-dimensional (3D) branched structures, twinned crystals, defects, etc. Utilizing in situ transmission electron microscopy techniques, researchers observed orientation-specific forces that act over short distances (∼1 nm) from the particle surfaces and drive the OA process. Integrating recently developed 3D fast force mapping via atomic force microscopy with theories and simulations, researchers have resolved the near-surface solution structure, the molecular details of charge states at particle/fluid interfaces, inhomogeneity of surface charges, and dielectric/magnetic properties of particles that influence short- and long-range forces, such as electrostatic, van der Waals, hydration, and dipole-dipole forces. In this review, we discuss the fundamental principles for understanding particle assembly and attachment processes, and the controlling factors and resulting structures. We review recent progress in the field via examples of both experiments and modeling, and discuss current developments and the future outlook.

Multistage Gradient Bioinspired Riblets for Synergistic Drag Reduction and Efficient Antifouling.

Shark skin-inspired riblets have represented the tremendous potential for drag reduction (DR) and antifouling in submarine, ship, and so on. Most studies simplified the complex denticle embedded in the shark skin into the single-stage riblet with uniform parameters, ignoring the influence of riblet height gradient and material deformation on DR and antifouling. In the present study, flexible multistage gradient riblets (MSGRs) with varied heights were proposed, and their DR and antifouling effects were investigated by the experiment and numerical simulation. The experimental results showed that the maximum DR rate of flexible MSGRs with an elastic modulus of 4.592 MPa could reach 16.8% at a flow velocity of 0.5 m/s. Moreover, the dynamic adhesion measurement indicated a reduction by 69.6% of the adhesion area of Chlorella vulgaris on the flexible MSGR surface. The results identified that flexible MSGRs with low surface energy could generate steady high- and low-velocity streaks and alter the flow state of the fluid, thus lessening the average velocity gradient near the wall and the adhering selectivity of pollutants in riblet and achieving synergistic DR and efficient antifouling. Taken together, the proposed flexible MSGR surface holds promise for reducing surface friction and inhibiting particle attachment in engineering applications.

Extraction and concentration of nanoplastic particles from aqueous suspensions using functionalized magnetic nanoparticles and a magnetic flow cell

Although a considerable knowledge base exists for environmental contamination from nanoscale and colloidal particles, significant knowledge gaps exist regarding the sources, transport, distribution, and effects of microplastic pollution (plastic particles < 5 mm) in the environment. Even less is known regarding nanoplastic pollution (generally considered to be plastic particles < 1 μm). Due to their small size, nanoplastics pose unique challenges and potential risks. We herein report a technique focused on the concentration and measurement of nanoplastics in aqueous systems. Hydrophobically functionalized magnetic nanoparticles (HDTMS-FeNPs) were used as part of a method to separate and concentrate nanoplastics from environmentally relevant matrices, here using metal-doped polystyrene nanoplastics (PAN-Pd@NPs) to enable low-level detection and validation of the separation technique. Using a magnetic separation flow cell, PAN-Pd@NPs were removed from suspensions and captured on regenerated cellulose membranes. Depending on the complexity of solution chemistry, variable extraction rates were possible. PAN-Pd@NPs were recovered from ultrapure water, synthetic freshwater, synthetic freshwater with a model natural organic matter isolate (NOM; Suwannee River Humic Acid), and from synthetic marine water, with recoveries for PAN-Pd@NPs of 84.9%, 78.9%, 70.4%, and 56.1%, respectively. During the initial method testing, it was found that the addition of NaCl was needed in the ultrapure water, synthetic freshwater and synthetic fresh water with NOM to induce particle aggregation and attachment. These results indicate that magnetic nanoparticles in combination with a flow-through system is a promising technique to extract nanoplastics from aqueous suspensions with various compositions.

Solution Structure and Hydration Forces between Mica and Hydrophilic Versus Hydrophobic Surfaces

Solid–liquid interfaces are central to a range of interesting phenomena including colloidal aggregation, crystallization by particle attachment, catalysis, heterogeneous nucleation, water desalination, and biomolecular assembly. While three-dimensional atomic force microscopy (3D AFM) has emerged as a technique for resolving interfacial solution structure at the molecular scale, key challenges for data interpretation persist, most notably regarding the influence of the probe on the measured structure. Using the mica–water system as a case study, we investigate the effect of hydrophilic and hydrophobic probes on interfacial solution structure measured by 3D AFM. Data from hydrophilic silicon-based probes are in good agreement with molecular dynamics simulations, wherein the innermost water molecules adsorb preferentially at the surface ditrigonal cavity sites, followed by two additional ordered hydration layers. In contrast, the hydrophobic carbon-based probes detect vertical oscillatory features but do not show lateral patterning that matches the underlying mica lattice. At high ionic strength, up to six of these oscillatory features are observed extending 2 nm into the solution phase with an average spacing of 0.29 ± (0.04) nm. We also determine that the repulsive hydration force between mica and the hydrophilic probe depends on the nature and concentration of ions in solution. Specifically, solutions with stronger ion–water and ion–ion interactions produce a stronger repulsive hydration force as the probe approaches the surface. Based on these observations, we present a scheme for controlling the outcomes of particle aggregation and attachment by varying the solution conditions to tune the hydration force.

Chikungunya virus entry and infectivity is primarily facilitated through cell line dependent attachment factors in mammalian and mosquito cells.

Chikungunya virus (CHIKV) is the causative agent of the human disease chikungunya fever, characterized by debilitating acute and chronic arthralgia. No licensed vaccines or antivirals are currently available for CHIKV. Therefore, the prevention of attachment of viral particles to host cells is a potential intervention strategy. As an arbovirus, CHIKV infects a wide variety of cells in both its mammalian and mosquito host. This broad cell tropism might stem from CHIKV's ability to bind to a variety of entry factors in the host cell including phosphatidylserine receptors (PSRs), glycosaminoglycans (GAGs), and the proteinaceous receptor Mxra8, among others. In this study, we aimed to determine the relevance of each attachment factor during CHIKV entry into a panel of mammalian and mosquito cells. Our data suggest that the importance of particular binding factors during CHIKV infection is highly cell line dependent. Entry into mammalian Vero cells was mediated through attachment to PSRs, mainly T-cell immunoglobulin mucin domain-1 (TIM-1). Conversely, CHIKV infection into HAP1 and NIH3T3 was predominantly mediated by heparan sulfate (HS) and Mxra8, respectively. Entry into mosquito cells was independent of PSRs, HS, and Mxra8. Although entry into mosquito cells remains unclear, our data denotes the importance of careful evaluation of reagents used to identify receptor use in invertebrate cells. While PSRs, GAGs, and Mxra8 all enhance entry in a cell line dependent manner, none of these factors are necessary for CHIKV entry, suggesting additional host factors are involved.

Surface Modification of Gold Nanoprisms and Their Self‐Assembly with Nanospheres

AbstractControlled surface modification of gold particles is of central importance for the preparation of functional nano‐objects, which can be used both in fundamental research and in advanced photonic or nanomedicine applications. In this study, the surface modification of gold nanoprisms using different thiols, namely cysteamine, (16‐mercaptohexadecyl)trimethylammonium bromide (MTAB), and α‐methoxy‐ω‐mercapto polyethylene glycol (mPEG‐SH (5000 Da)) is investigated. The aim is to prepare binary surface‐modified thiol/PEG patchy gold nanoprisms, where the tips/edges and the face regions of the particles are covered by different thiol moieties. By investigating the time evolution of the prisms’ extinction spectra at different capping ligand concentration levels, the conditions to prepare such “patchy” particles are identified. While significantly faster adsorption kinetics are observed for MTAB compared to cysteamine, both molecule types can be used to prepare binary surface‐modified thiol/PEG particles. Prisms modified with only MTAB or PEG and subsequently assembled with negatively charged spheres show that MTAB forms hetero‐aggregates with the spheres, while PEG prevents particle attachment. For thiol (cysteamine or MTAB)/PEG binary surface‐modified prisms, it is found that the efficiency of sphere attachment at the tip/side region during self‐assembly is rather low, most likely due to the presence of PEG.

Asymmetrically coupled two lane totally asymmetric simple exclusion process with extended Langmuir kinetics

The proposed study is motivated by the transport phenomena where the particle hopping, attachment, and detachment dynamics rely on the occupancy state of the corresponding site on another lane. To depict this kind of scenario, we consider an open two-lane Totally Asymmetric Simple Exclusion Process with the presence of asymmetrically coupled and extended Langmuir kinetics regulations. We have analyzed the steady-state properties of the system by calculating characteristics including phase diagrams, density profiles, phase transitions, and finite size effect. The theoretical results are captured by utilizing the framework of a mean-field theory, and it is recognized that numerical findings match closely with the Monte Carlo simulation outcomes.

Role of hydrophobic fine particles in coarse particle flotation: An analysis of bubble-particle attachment and detachment

It is widely accepted that hydrophobic fine particles improve froth stability and thus increase the recovery of coarse particles in the froth phase. In fact, the presence of fine particles also enhances coarse particle recovery in the collection zone. It is not yet known what causes this, nor is it known how fine particles affect interactions between bubbles and coarse particles (collision, attachment, and detachment). In the present study, the role of hydrophobic fine particles in improving the recovery of coarse particles in the pulp phase was discussed from the perspective of bubble-particle interaction. Flotation tests of coarse particles with different fine particle contents were first carried out. The bubble collision-attachment test, bubble-particle aggregate stability test, and interaction force test were used to further explain the effects of fine particle coverage on bubble-particle interactions. The results show that the recovery of coarse particles increases as the fine particle content in the flotation feed increases. Although the presence of hydrophobic fine particles prevents the rupture of the liquid film and the formation of the contact line between bubble and coarse particle, it can also greatly increase contact angle hysteresis, increasing the maximum force required to pull coarse particle from the gas-liquid interface into the aqueous phase. Furthermore, the coverage of fine particles helps to improve the energy dissipation during the bubble collision and reduce the oscillation of the bubble-particle aggregates. As a result, the increase in coarse particle recovery in the presence of fine particles is due to the decrease in the detachment of the bubble-particle aggregate. The important findings of this study are expected to provide a basis for understanding the interaction between multiple particles and bubbles in actual flotation.

Bioprocess inspired formation of calcite mesocrystals by cation-mediated particle attachment mechanism.

Calcite mesocrystals were proposed, and have been widely reported, to form in the presence of polymer additives via oriented assembly of nanoparticles. However, the formation mechanism and the role of polymer additives remain elusive. Here, inspired by the biomineralization process of sea urchin spine comprising magnesium calcite mesocrystals, we show that calcite mesocrystals could also be obtained via attachment of amorphous calcium carbonate (ACC) nanoparticles in the presence of inorganic zinc ions. Moreover, we demonstrate that zinc ions can induce the formation of temporarily stabilized amorphous nanoparticles of less than 20nm at a significantly lower calcium carbonate concentration as compared to pure solution, which is energetically beneficial for the attachment and occlusion during calcite growth. The cation-mediated particle attachment crystallization significantly improves our understanding of mesocrystal formation mechanisms in biomineralization and offers new opportunities to bioprocess inspired inorganic ions regulated materials fabrication.

Impact of biochar coexistence with polar/nonpolar microplastics on phenanthrene sorption in soil

Microplastics and biochar normally coexist in soil. In this study, two microplastics of different polarities (nonpolar polyethylene (PE) and polar polybutylene adipate-co-terephthalate (PBAT)) and two wheat straw biochars produced at 400 (W4) and 700 °C (W7) were selected to investigate the sorption behaviors of phenanthrene in soil where microplastics and biochar coexisted. The results showed that the presence of PE more significantly weakened the adhesion of soil particles onto biochar than the presence of PBAT. Meanwhile, the presence of biochar enhanced the soil particle attachment on the microplastic surface. As a result, the sorption behavior of phenanthrene was significantly different in soil where biochar coexisted with microplastics of different polarities. The Koc values of PE-biochar-soil mixtures at Ce= 0.005 Cs were up to 42 % lower than those of PBAT-biochar-soil mixtures, which is related to lower micropore area of particles isolated from the former. However, at Ce = 0.05 Cs and 0.5 Cs, the Koc values of PE-biochar-soil mixtures were up to 1.4 times higher than those of PBAT-biochar-soil mixtures because of a more significant reduction in biochar surface polarity when it coexisted with nonpolar PE.

In Situ Imaging of Faujasite Surface Growth Reveals Unique Pathways of Zeolite Crystallization.

Zeolite crystallization occurs by complex processes involving a variety of possible mechanisms. The sol gel media used to prepare zeolites leads to heterogeneous mixtures of solution and solid states with diverse solute species. At later stages of zeolite synthesis when growth occurs predominantly from solution, classical two-dimensional nucleation and spreading of layers on crystal surfaces via the addition of soluble species is the dominant pathway. At earlier stages, these processes occur in parallel with nonclassical pathways involving crystallization by particle attachment (CPA). The relative roles of solution- and solid-state species in zeolite crystallization have been a subject of debate. Here, we investigate the growth mechanism of a commercially relevant zeolite, faujasite (FAU). In situ atomic force microscopy (AFM) measurements reveal that supernatant solutions extracted from a conventional FAU synthesis at various times do not result in growth, indicating that FAU growth predominantly occurs from the solid state through a disorder-to-order transition of amorphous precursors. Elemental analysis shows that supernatant solutions are significantly more siliceous than both the original growth mixture and the FAU zeolite product; however, in situ AFM studies using a dilute clear solution with a lower Si/Al ratio revealed three-dimensional growth of surfaces that is distinct from layer-by-layer and CPA pathways. This unique mechanism of growth differs from those observed in studies of other zeolites. Given that relatively few zeolite frameworks have been the subject of mechanistic investigation by in situ techniques, these observations of FAU crystallization raise the question whether its growth pathway is characteristic of other zeolite structures.