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Nanoparticle-based therapeutics have been used in pulmonary formulations to enhance delivery of poorly water-soluble drugs, protect drugs against degradation and achieve modified release and drug targeting. This review focuses on the use of spray drying as a solidification technique to produce microparticles containing nanoparticles (i.e., nanoparticle (NP) agglomerates) with suitable properties as dry powders for inhalation. The review covers the general aspects of pulmonary drug delivery with emphasis on nanoparticle-based dry powders for inhalation and the principles of spray drying as a method for the conversion of nanosuspensions to microparticles. The production and therapeutic applications of the following types of NP agglomerates are presented: nanoporous microparticles, nanocrystalline agglomerates, lipid-based and polymeric formulations. The use of alternative spray-drying techniques, namely nano spray drying, and supercritical CO2-assisted spray drying is also discussed as a way to produce inhalable NP agglomerates.

In this study, several simple equations are suggested to investigate the effects of size and density on the number, surface area, stiffening efficiency, and specific surface area of nanoparticles in polymer nanocomposites. In addition, the roles of nanoparticle size and interphase thickness in the interfacial/interphase properties and tensile strength of nanocomposites are explained by various equations. The aggregates/agglomerates of nanoparticles are also assumed as large particles in nanocomposites, and their influences on the nanoparticle characteristics, interface/interphase properties, and tensile strength are discussed. The small size advantageously affects the number, surface area, stiffening efficiency, and specific surface area of nanoparticles. Only 2 g of isolated and well-dispersed nanoparticles with radius of 10 nm ( R  = 10 nm) and density of 2 g/cm 3 produce the significant interfacial area of 250 m 2 with polymer matrix. Moreover, only a thick interphase cannot produce high interfacial/interphase parameters and significant mechanical properties in nanocomposites because the filler size and aggregates/agglomerates also control these terms. It is found that a thick interphase ( t  = 25 nm) surrounding the big nanoparticles ( R  = 50 nm) only improves the B interphase parameter to about 4, while B  = 13 is obtained by the smallest nanoparticles and the thickest interphase.

The quantification of microplastics (MP) in environmental samples is currently a challenging task. To enable low quantification limits, an analytical method has been developed combining pressurized liquid extraction (PLE) and pyrolysis GC-MS. The automated extraction includes a pre-extraction step via methanol followed by a subsequent PLE using tetrahydrofuran. For the most frequently used synthetic polymers polyethylene (PE), polypropylene (PP), and polystyrene (PS), limits of quantification were achieved down to 0.007 mg/g. Recoveries above 80% were attained for solid matrices such as soil and sediments. The developed method was applied for MP quantification in environmental samples such as sediment, suspended matter, soil, and sewage sludge. In all these matrices, PE and PP were detected with concentrations ranging from 0.03 to 3.3 mg/g. In sewage sludge samples, all three polymers were present with concentration levels ranging between 0.08 ± 0.02 mg/g (PP) and 3.3 ± 0.3 mg/g (PE). However, especially for solid samples, the analysis of triplicates revealed elevated statistical uncertainties due to the inhomogeneous distribution of MP particles. Thus, care has to be taken when milling and homogenizing the samples due to the formation of agglomerates.

In this work, we investigated the effect of carbon nanotubes addition and agglomeration formation on the mechanical and electrical properties of CNT–polymer-based nanocomposites. Six specimens with carbon nanotubes (CNTs) fractions of 0%, 0.5%, 1%, 2%, 4% and 5% were manufactured and characterized by dynamic mechanical analysis (DMA) and four-probe method. The stress–strain curves and electrical conductivity properties were obtained. Scanning electron microscopy (SEM) was used to characterize both agglomeration and porosity formation. By employing micromechanics, through representative volume element (RVE), finite element analysis (FEA) and resistor network model (RNM), the Young’s modulus and electrical conductivity values were calculated. The samples’ elastic moduli showed an increment, reaching the maximum value at a CNTs fraction of 2%, thereafter an adverse effect was caused in the high CNT percentage samples. The final electrical conductivity seemed greatly altered with the addition of CNTs, reaching the percolation threshold at 2%. The unavoidable formation of CNT agglomerates appeared to influence the final physical properties. The CNT agglomerates adversely affect the mechanical performance of high-CNT-percentage samples. Conversely, an exponential increment in the electrical conductivity was presented as the agglomerates formed networks allowing the transport of electrons through the tunnelling effect. These phenomena were experimentally and numerically confirmed, showing a good correlation.

Blood clot contraction plays an important role in prevention of bleeding and in thrombotic disorders. Here, we unveil and quantify the structural mechanisms of clot contraction at the level of single platelets. A key elementary step of contraction is sequential extension–retraction of platelet filopodia attached to fibrin fibers. In contrast to other cell–matrix systems in which cells migrate along fibers, the “hand-over-hand” longitudinal pulling causes shortening and bending of platelet-attached fibers, resulting in formation of fiber kinks. When attached to multiple fibers, platelets densify the fibrin network by pulling on fibers transversely to their longitudinal axes. Single platelets and aggregates use actomyosin contractile machinery and integrin-mediated adhesion to remodel the extracellular matrix, inducing compaction of fibrin into bundled agglomerates tightly associated with activated platelets. The revealed platelet-driven mechanisms of blood clot contraction demonstrate an important new biological application of cell motility principles. Blood clot contraction is a cellular (patho)physiological process essential for wound healing, hemostasis, and thrombosis. Here, the authors describe the physical structural mechanism by which platelet filopodia pull “hand-over-hand” on fibrin fibers to compact them into bundled agglomerates.

Preparation of nanofluid is of prime importance to obtain better thermal and physical properties. Different preparation parameters used in nanofluid preparation sometimes perform contrarily even if prepared with same nanoparticles and base fluid. Stability, thermal conductivity, and viscosity of the nanofluid are significantly affected by the cluster (agglomerate) size of nanoparticles in the base fluid which deteriorate thermal performance. In order to break the agglomerates and improve the dispersion of nanoparticles, ultrasonication is a more prevalent method. Nanofluids react differently for different sonication time and the reaction of the nanofluid with the change in sonication time varies for different nanofluids, which is dependent on various factors. In this regard, research works pertinent to the effect of ultrasonication on different properties of nanofluids are confined. In this paper, review of investigations carried out on experimentally evaluated ultrasonication effects on thermal properties and various physical properties of nanofluid. It is found that with an increased sonication time/energy, reduces the particle size and thus aids in obtaining a better dispersion leading to enhancement of stability, thermal conductivity and reducing viscosity. However, the longer ultrasonication duration was not found to be better in all cases where best performance was obtained for an optimum duration of ultrasonication.

An aerosolized liquid phase reaction method is proposed for the continuous preparation of highly dispersed copper nanoparticles. The copper precursor solution and reducing agent solution are mixed and aerosolized immediately into microdroplets, which prevents the synthesized copper nanoparticles from coming into contact and forming agglomerates. Compared to the traditional liquid phase synthesis of copper nanoparticles, this method reduces the average size of the nanoparticles from 309 to 210 nm and the maximum size of the agglomerates from ~ 10 to ~ 3 μm. As a result, the shear strength of the sintered joint made with the aerosol-produced nanoparticles is improved from 33 to 57 MPa, and the electrical resistance is reduced from 4.3 × 10 –7 to 6.1 × 10 –8 Ω·m. This method provides an effective approach to decrease agglomeration and improve the performance of metal nanoparticles for electronic packaging applications. Graphical Abstract

In this study, dry dispersion laser diffraction was used to study the dispersibility of spheronized agglomerate formulations and identify geometric particle size metrics that correlated well with aerodynamic particle size distribution (APSD). Eleven unique batches of agglomerates were prepared for both laser diffraction and cascade impaction testing. Correlations between the particle size distribution (PSD) and aerodynamic particle size distribution (APSD) metrics for the eleven agglomerate batches were determined in a semi-empirical manner. The strongest correlation between APSD and PSD was observed between the impactor-sized mass (%ISM) and the cumulative PSD fraction <14.5 µm. The strongest correlation with fine particle fraction (FPF) was observed with the cumulative PSD fraction <0.99 micron ( R -squared = 0.974). In contrast to the other APSD metrics, good correlations were not found between the mass median aerodynamic diameter (MMAD) and the cumulative PSD fractions. Overall, the implementation of laser diffraction as a surrogate for cascade impaction has the potential to streamline product development. Laser diffraction measurements offer savings in labor and turnaround time compared to cascade impaction. Graphical Abstract

We tested the suitability of asymmetric flow field-flow fractionation (AF4) coupled to multi-angle light scattering (MALS) for detection of nanoplastics in fish. A homogenized fish sample was spiked with 100 nm polystyrene nanoparticles (PSNPs) (1.3 mg/g fish). Two sample preparation strategies were tested: acid digestion and enzymatic digestion with proteinase K. Both procedures were found suitable for degradation of the organic matrix. However, acid digestion resulted in large PSNPs aggregates/agglomerates (> 1 μm). The presence of large particulates was not observed after enzymatic digestion, and consequently it was chosen as a sample preparation method. The results demonstrated that it was possible to use AF4 for separating the PSNPs from the digested fish and to determine their size by MALS. The PSNPs could be easily detected by following their light scattering (LS) signal with a limit of detection of 52 μg/g fish. The AF4-MALS method could also be exploited for another type of nanoplastics in solution, namely polyethylene (PE). However, it was not possible to detect the PE particles in fish, due to the presence of an elevated LS background. Our results demonstrate that an analytical method developed for a certain type of nanoplastics may not be directly applicable to other types of nanoplastics and may require further adjustment. This work describes for the first time the detection of nanoplastics in a food matrix by AF4-MALS. Despite the current limitations, this is a promising methodology for detecting nanoplastics in food and in experimental studies (e.g., toxicity tests, uptake studies).

The internal recycling of iron-rich fine residues is a crucial process for reducing the raw material loss and the carbon footprint in sustainable ironmaking and steelmaking. Traditionally, cement has been used as a binder to ensure the structural integrity of agglomerates during transport and charging. While cementitious binder can achieve the necessary structural support, it contributes significantly to the carbon footprint. This study investigated the effects of alternative biogenic binders and varying compaction pressures on the physical and mechanical properties of agglomerates produced from three different types of fine residues from steel (SR) and cast-iron (FR) production. In addition, the self-reducing capability and degree of metallization of these agglomerates were evaluated through pyrometallurgical experiments in a Tammann furnace. The resulting agglomerates exhibited sufficient mechanical strength and high iron recovery rates. These findings confirm that biogenic binders can effectively replace cementitious binders without compromising the self-reduction performance of the agglomerates.