High Monodispersity Research Articles

Ligands of Nanoparticles and Their Influence on the Morphologies of Nanoparticle-Based Films.

Nanoparticle-based thin films are increasingly being used in various applications. One of the key factors that determines the properties and performances of these films is the type of ligands attached to the nanoparticle surfaces. While long-chain surfactants, such as oleic acid, are commonly employed to stabilize nanoparticles and ensure high monodispersity, these ligands often hinder charge transport due to their insulating nature. Although thermal annealing can remove the long-chain ligands, the removal process often introduces defects such as cracks and voids. In contrast, the use of short-chain organic or inorganic ligands can minimize interparticle distance, improving film conductivity, though challenges such as incomplete ligand exchange and residual barriers remain. Polymeric ligands, especially block copolymers, can also be employed to create films with tailored porosity. This review discusses the effects of various ligand types on the morphology and performance of nanoparticle-based films, highlighting the trade-offs between conductivity, structural integrity, and functionality.

Development of a two-stage virtual impactor for the generation of micrometer-scale monodisperse aerosols

Monodisperse particles are useful across a wide range of industrial applications, such as LCD displays, solar cells and rechargeable batteries, due to their uniformly small sizes. However, generating high volumes of monodisperse particles remains challenging. In this study, it was aimed to generate monodisperse aerosols by classifying micrometer-scale solid aerosol particles within a narrow size range. Accordingly, a new particle-size classification device with two virtual impactors connected in series and clean air cores was developed. The first-stage virtual impactor had a slightly larger cutoff size than the second-stage, and the major flow discharged from the first-stage was directed to the second-stage. The target particle size range was altered by changing the nozzle sizes in the first and second stages or by adjusting the flow rate. Subsequently, the classification performance of the two-stage virtual impactor was simulated and validated through an experiment using Arizona test dust. The implemented combinations of cutoff sizes for the first and second stages were 3.0 and 2.0 μm, 3.9 and 2.7 μm, or 6.7 and 4.8 μm. As a result, monodisperse aerosol particles were classified at a geometric standard deviation of 1.04–1.14 and a particle size range of 2–6.7 μm. The two-stage virtual impactor developed herein may be useful for various research and performance evaluations, as it can classify micrometer-scale solid particle aerosols that exhibit high monodispersity.

Systematic Study of Reaction Conditions for Size-Controlled Synthesis of Silica Nanoparticles.

This study presents a reproducible and scalable method for synthesizing silica nanoparticles (SNPs) with controlled sizes below 200 nm, achieved by systematically varying three key reaction parameters: ammonium hydroxide concentration, water concentration, and temperature. SNPs with high monodispersity and controlled dimensions were produced by optimizing these factors. The results indicated a direct correlation between ammonium hydroxide concentration and particle size, while higher temperatures resulted in smaller particles with increased polydispersity. Water concentration also influenced particle size, with a quadratic relationship observed. This method provides a robust approach for tailoring SNP sizes, with significant implications for biomedical applications, particularly in drug delivery and diagnostics. Using eco-friendly solvents such as ethanol further enhances the sustainability and cost-effectiveness of the process.

Growth Mechanisms of Amorphous Nanoparticles in Solution and During Heat Drying

The purpose of this study was twofold: to identify the growth mechanisms of amorphous nanoparticles in solution and during the drying process at high temperatures, and to guide the process condition and stabilizer selection for amorphous nanoparticle formulations. In contrast to nanocrystals that are mostly mechanically robust, amorphous nanoparticles tend to undergo deformation under stress. As a result, development of a stable formulation and evaluation of the drying process for re-dispersible amorphous nanoparticles presents considerable challenges. Although amorphous nanoparticles have stability issues, they have several pros in terms of production, high monodispersity, and diverse applications in drug delivery. In this study, amorphous nanoparticles were prepared via liquid-liquid phase separation, and their growth mechanisms were investigated both in solution and during the drying process. In solution, particles were found to be susceptible to flocculation, crystallization, coalescence, and Ostwald ripening, with coalescence being a preliminary step providing the driving force for Ostwald ripening. However, during the heat drying process, coalescence and crystallization were found to be the primary mechanisms for particle growth, with Ostwald ripening being negligible due to reduced molecular mobility. The glass transition temperature (Tg) of these amorphous nanoparticles was found to be a crucial factor both in solution and during the drying process. At temperatures < Tg, particles remained in a rigid, glassy state thereby inhibiting coalescence, whereas at or above Tg, particles transition from glassy to rubbery state, making them more susceptible to deformation and coalescence. The mechanistic understanding of particle growth from this study can also be extended to the stabilization of other types of soft nanoparticles.

Size controlled synthesis of hydrous TiO2 spheres by a thiol structure directing agent and its application in photocatalysis and efficient DSSC cells

In this work, hydrated TiO2 spheres (HTS) of the submicron order have been developed. Normally, the group of amines, such as dodecylamine, hexadecylamine, methylamine, and NH3, had been the main structure-directing agents (SDAs) used in the sol–gel process to obtain monodisperse hydrated TiO2 spheres. Even though progress has been made in the synthesis of HTS, it is crucial to include new SDAs capable of synthesizing monodisperse HTS with improved or new properties for practical applications. In this work, for the first time we demonstrate that a thiol, 3-mercaptopropionic acid (MPA), can be used as an effective SDA to synthesize monodisperse hydrous TiO2 spheres with a controllable particle diameter between 150 to 950 nm. Experimental preparation parameters such as Ti concentration, [MPA]/[Ti] and [Water]/[Ti] molar ratio in the precursor solution (Titanium (IV) butoxide—MPA—ethanol—water) were thoroughly optimized to get both high yield and high monodispersity. Remarkably, a wide range in the [Water]/[Ti] molar ratio, 17 to 118, was achieved, which is much wider than the typical Rw range of the amines group of 2 to 16, thus giving more control for choosing the HTS final size. The controlled growth of hydrated TiO2 nanospheres was explained according to the LaMer and DVLO theory. To demonstrate the applicability of the HTS synthesized using MPA as SDA, the development of efficient dye-sensitized solar cells getting an energy conversion greater than 9% as well as of an effective photocatalytic degradation process of the analgesic acetaminophen under concentrated solar radiation was conducted.

Novel pH- and thermal-responsive oleogel capsules: Featuring an oleogel core and ultrathin calcium-alginate shell

Oleogels have been explored as a new lipid-based delivery system, however, their insolubility and unsuitable shape severely limit their application in food systems. Herein, core-shell oleogel capsules with high monodispersity (coefficient variation (CV) < 5%)) were prepared via gravity-assisted co-flowing microfluidic device and simply air-drying. The oleogel capsules with oleogel core and ultrathin calcium-alginate shell were prepared. Oleogel capsules maintained their original shape at pH = 2.0 but swelled rapidly at pH = 6.8 and 7.4. The swelling ratio of shell can be adjusted by inner fluid flow rate (Qin). Notably, the core with beeswax (BW) crystal network, effectively improved the stability performances and also could provide thermal response. Finally, the oleogel capsules demonstrated excellent sustained release and UV protection of lipophilic bioactives. This work sheds light on development of novel oleogel capsules, making them ideal candidates for smart food encapsulation applications.

Formation of magnetic double emulsions under steady and variable magnetic fields from a 3D-printed coaxial capillary device

BackgroundDouble emulsions (DEs) have attracted researchers’ attention to be utilized as a promising platform in biomedical and chemical applications. Several actuation mechanisms have been proposed for the generation of DEs. The conventional DE formation approaches (e.g. two-stage emulsification) suffer from low monodispersity. The electric actuation (i.e. coaxial electrospray technology) has been demonstrated as a controllable method for the DE formation, while the capability of magnetic actuation has not been studied yet. ResultIn the present study, the generation of ferrofluid double emulsions (FDEs), made from water-based ferrofluid as a core and oil as a shell, under the magnetic actuation of a permanent magnet with a steady magnetic field and an electromagnet with DC and pulse width modulation (PWM) magnetic fields was investigated with a simple controllable setup fabricated using 3D printing. The effect of various parameters affecting the FDE formation, such as the fluid flow rates, the magnetic field type, the magnetic flux density, and the PWM frequency and duty cycle, on the FDE formation characteristics, including the inner and outer equivalent diameters, and the formation frequency was studied. Under the steady magnetic field, two regimes of the FDE formation were identified: inertia-dominated and magnet-dominated. SignificanceWireless power-free magnetic actuation provides better control over the FDE formation, enhancing this process by increasing the FDE formation frequency with high monodispersity. The PWM magnetic field offers excellent controllability over the FDE formation with low-volume or no, in some cases, satellite droplets by tuning the PWM frequency and the duty cycle.

Glass Microdroplet Generator for Lipid-Based Double Emulsion Production.

Microfluidics offers a highly controlled and reproducible route to synthesize lipid vesicles. In recent years, several microfluidic approaches have been introduced for this purpose, but double emulsions, such as Water-in-Oil-in-Water (W/O/W) droplets, are preferable to produce giant vesicles that are able to maximize material encapsulation. Flow focusing (FF) is a technique used to generate double emulsion droplets with high monodispersity, a controllable size, and good robustness. Many researchers use polydimethylsiloxane as a substrate material to fabricate microdroplet generators, but it has some limitations due to its hydrophobicity, incompatibility with organic solvents, and the molecular adsorption on the microchannel walls. Thus, specific surface modification and functionalization steps, which are uncomfortable to perform in closed microchannels, are required to overcome these shortcomings. Here, we propose glass as a material to produce a chip with a six-inlet junction geometry. The peculiar geometry and the glass physicochemical properties allow for W/O/W droplet formation without introducing microchannel wall functionalization and using a variety of reagents and organic solvents. The robust glass chip can be easily cleaned and used repeatedly, bringing advantages in terms of cost and reproducibility in emulsion preparation.

One Step Superparamagnetic Iron Oxide Nanoparticles by a Microwave Process: Optimization of Microwave Parameters with an Experimental Design

AbstractSuperparamagnetic iron oxide nanoparticles (SPIONs) are nanoparticles used in a lot of applications such as batteries, and biomedical, … To obtain these nanoparticles, several techniques exist such as coprecipitation, thermal decomposition, sol–gel process but they have some advantages (synthesis in a water media, high crystallinity, high monodispersity) and disadvantages (using an organic solvent, large distribution of size, poor crystallinity). The goal of this work is to synthesize SPIONs for biomedical applications (for example as a contrast agent for the MRI): SPIONs should be stable in an aqueous media, monodisperse, and have good crystallinity and magnetic properties. To achieve this result, a microwave process is carried out. However, any study describes the microwave parameter on the synthesis of the nanoparticles. This work offers to determine the best conditions of the microwave to obtain ideal SPIONs for MRI. For this, an experimental design is carried out to determine these parameters thanks to different techniques of characterization (Transmission Electronic Microscopy, Dynamic Light Scattering, X‐ray diffraction, Thermogravimetric Analysis, magnetic characterizations). With the different results of these characterizations, the best conditions of the microwave are determined, and a simulation of all experiments is realized with a surface response.

Facile synthesis of Gd/Ru-doped fluorescent carbon dots for fluorescent/MR bimodal imaging and tumor therapy

Functional metal doping endows fluorescent carbon dots with richer physical and chemical properties, greatly expanding their potential in the biomedical field. Nonetheless, fabricating carbon dots with integrated functionality for diagnostic and therapeutic modalities remains challenging. Herein, we develop a simple strategy to prepare Gd/Ru bimetallic doped fluorescent carbon dots (Gd/Ru-CDs) via a one-step microwave-assisted method with Ru(dcbpy)3Cl2, citric acid, polyethyleneimine, and GdCl3 as precursors. Multiple techniques were employed to characterize the morphology and properties of the obtained carbon dots. The Gd/Ru-CDs are high mono-dispersity, uniform spherical nanoparticles with an average diameter of 4.2 nm. Moreover, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) confirmed the composition and surface properties of the carbon dots. In particular, the successful doping of Gd/Ru enables the carbon dots not only show considerable magnetic resonance imaging (MRI) performance but also obtain better fluorescence (FL) properties, especially in the red emission area. More impressively, it has low cytotoxicity, excellent biocompatibility, and efficient reactive oxygen species (ROS) generation ability, making it an effective imaging-guided tumor treatment reagent. In vivo experiments have revealed that Gd/Ru-CDs can achieve light-induced tumor suppression and non-invasive fluorescence/magnetic resonance bimodal imaging reagents to monitor the treatment process of mouse tumor models. Thus, this simple and efficient carbon dot manufacturing strategy by doping functional metals has expanded avenues for the development and application of multifunctional all-in-one theranostics.

Size-tunable and monodisperse lead sulfide quantum dots for broadband photodetectors

Lead sulfide quantum dots (PbS QDs) are used in broadband photodetectors due to their excellent size tunability, photosensitivity, and solution processability. However, due to the risk of Ostwald ripening, synthesizing high-quality PbS QDs with absorption peaks over 2000 nm with high monodispersity is a challenge. In this study, by controlling the molar ratio of Pb to S and the number of injections of S precursor, we successfully prepared large PbS QDs with an absorption peak at 2122 nm, corresponding to an average diameter of 11.42 nm, with a super-mono-dispersity of 5.50%. Broadband photodetectors ranging from visible light to short-wave infrared are prepared using the large PbS QDs, corresponding to a response rate of 5.98 mA/W at 1940 nm.

Unveiling the Nanocluster Conversion Pathway for Highly Monodisperse InAs Colloidal Quantum Dots.

Colloidal quantum dots (CQDs) have garnered significant attention in nanoscience and technology, with a particular emphasis on achieving high monodispersity in their synthesis. Recent advances in understanding the chemistry of reaction intermediates such as magic-sized nanoclusters (MSC) have paved the way for innovative synthetic strategies. Notably, monodisperse CQDs of various compositions, including indium phosphide, indium arsenide, and cadmium chalcogenide, have been successfully prepared using nanocluster intermediates as single-source precursors. Still, the early stage conversion chemistry of these nanoclusters preceding CQD formation has not been fully unveiled yet. Herein, we report the first-order conversion of amorphous nanoclusters (AMCs) to InAs MSCs prior to the formation of CQDs. We find that MSC, isolated via gel-permeation chromatography, is more stable than purified AMCs, as demonstrated in various chemical and thermolytic reactions. While the surface of InAs AMCs and MSC is similarly bound with carboxylate ligands, detailed structural analyses employing synchrotron X-ray scattering and X-ray absorption spectroscopy unveil subtle distinctions arising from the distinct surface properties and structural disorder characteristics of InAs nanoclusters. We propose that InAs AMCs undergo a surface reduction and structural ordering process, resulting in the formation of an InAs MSC in a thermodynamically local minimum state. Furthermore, we demonstrate that both types of nanoclusters serve as viable precursors, providing a similar monomer supply rate at elevated temperatures of around 300 °C. This study offers invaluable insights into the interplay of structure and chemical stability in binary nanoclusters, enhancing our ability to design these nanoclusters as precursors for highly monodisperse CQDs.

A universal strategy for green and surfactant-free synthesis of noble metal nanoparticles.

We propose a universal, green, and surfactant-free strategy to synthesize noble metal particles with high monodispersity using gaseous H2 as a reducing agent in a solution at 60 °C. The prepared Pt nanoparticles have a 24 mV more positive half-wave potential than the commercially available Pt/C in the oxygen reduction reaction, while showing high durability with negligible half-wave potential decay after 10 000 cycles of testing.

Efficient monodisperse upconversion composite prepared using high-density local field and its dual-mode temperature sensing.

Enhanced upconversion via plasmonics has considerable potential in biosensors and solar cells; however, conventional plasmonic configurations such as core-shell assemblies or nanoarray platforms still suffer from the compromise between the enhancement factor and monodispersity, which has failed to meet the requirement of the materials for the in vivo all-solution-prepared solar cells and biosensors. We herein report a monodisperse metal-dielectric-metal (MDM) type upconverted hybrid material with high efficiency. The lanthanide-doped upconversion nanoparticles (UCNPs) were sandwiched by two gold nanodisk mirrors, and the highly localized excitation field around the UCNPs together with the efficient coupling enhanced the upconversion. The upconversion intensity can then be effectively regulated and improved by three to four orders of magnitude. As per the measurement of the temperature-dependent fluorescence intensity and spectra shift, a dual-mode nanothermometer based on our proposed hybrid materials was demonstrated. This MDM-type upconverted hybrid material demonstrated the merits of high efficiency and monodispersity, which demonstrated promise in in vivo biosensors and solar cell fabrication techniques such as spin-coating and roll-to-roll.

Massive and efficient encapsulation of single cells in monodisperse droplets and collagen-alginate microgels using a microfluidic device.

Single-cell manipulation is the key foundation of life exploration at individual cell resolution. Constructing easy-to-use, high-throughput, and biomimetic manipulative tools for efficient single-cell operation is quite necessary. In this study, a facile and efficient encapsulation of single cells relying on the massive and controllable production of droplets and collagen-alginate microgels using a microfluidic device is presented. High monodispersity and geometric homogeneity of both droplet and microgel generation were experimentally demonstrated based on the well-investigated microfluidic fabricating procedure. The reliability of the microfluidic platform for controllable, high-throughput, and improved single-cell encapsulation in monodisperse droplets and microgels was also confirmed. A single-cell encapsulation rate of up to 33.6% was achieved based on the established microfluidic operation. The introduction of stromal material in droplets/microgels for encapsulation provided single cells an in vivo simulated microenvironment. The single-cell operation achievement offers a methodological approach for developing simple and miniaturized devices to perform single-cell manipulation and analysis in a high-throughput and microenvironment-biomimetic manner. We believe that it holds great potential for applications in precision medicine, cell microengineering, drug discovery, and biosensing.

INFLUENCE OF YAG CERAMIC POWDERS GRINDING CONDITIONS OF ON THE PROPERTIES OF OPTICAL CERAMICS

In this study, the changes in the morphology and degree of agglomeration of both precursor powders and ceramic YAG powders under varying grinding conditions was considered. The effect of these parameters on the optical properties and structure of the ceramics was assessed. The YAG precursor powders were obtained through chemical co-precipitation. The morphology, size of agglomerates, and crystallites was evaluated using scanning electron microscopy, laser diffraction analysis, X-ray phase analysis, and Brunauer–Emmett–Teller gas adsorption. It was found that milling the YAG precursor powders allows for a reduction in the degree of agglomeration of the ceramic powders. It was discovered that optimal modes can be achieved at a mass ratio of grinding balls to precursor powder of 6.75/1 and a ratio of the mass of the grinding medium to the mass of the precursor powder of 4.5/1. These modes provide the necessary granulometric characteristics and the highest monodispersity. Therefore, it has been demonstrated that the use of an additional milling stage for powders synthesized by chemical precipitation, along with the selection of milling modes, can improve the properties of YAG optical ceramics.

Particle-resolved direct numerical simulation of particle-laden turbulence modulation with high Stokes number monodisperse spheres

Graphic processing units (GPU)-accelerated direct numerical simulations of particle–fluid systems based on lattice Boltzmann method combined with discrete element method are successfully performed. This method is validated to be accurate and efficient in the four-way coupling simulation of particle–fluid systems. Particle-laden homogeneous isotropic turbulence under particle size dp=30.1η (the Kolmogorov length scale), a wide range of solid volume fraction ϕV=2%−20% and particle Stokes number St=503.87−50 387 are systematically studied. The additional energy dissipation rate εaddi induced by particles is quantitatively calculated. One criterion for turbulence enhancement or attenuation based on energy balance is proposed and successfully used in different particle-laden turbulence. The relative magnitude of two-way coupling rate ψ and particle-induced dissipation εaddi is the direct factor determining the modulation effect on turbulence. Turbulence laden with high Stokes number particles is enhanced. Turbulence laden with high volume fraction particles transited rapidly from enhancement to attenuation, which is attributed to the more rapid decay of ψ relative to εaddi in the freely decaying turbulence.

Preparation, characterization and in vitro anticancer efficacy of biotin-conjugated, silibinin loaded bovine serum albumin nanoparticles

Silibinin (SBN) is a natural, plant-derived bioactive flavonolignan, possessing wide range of pharmaceutical activities including anticancer. However, poor aqueous solubility and low oral bioavailability restrict its clinical applications. Protein based nanomedicines have emerged as a potential solution to improve the delivery of hydrophobic anticancer agents like SBN. Further, Biotin functionalization of delivery vehicle can provide the added advantage of increased aqueous solubility, controlled drug release and site-specific delivery at the tumor. In the present work, we have prepared biotin conjugated bovine serum albumin nanoparticles (Biotin@BSA-NPs) for the efficient delivery of SBN to cancer cells. The prepared SBN loaded Biotin@BSA-NPs (Biotin@SBN-BSA-NPs) showed nanoscale size (∼157 nm), high monodispersity (PDI 0.102), high encapsulation efficiency (∼83%), and controlled pH-dependent drug release. Biotin@SBN-BSA-NPs reveals dose-dependent and time-dependent cytotoxicity against human cervical cancer (HeLa) cells. The cellular uptake study, MTT assay and AO-EtBr staining assay demonstrate that Biotin@SBN-BSA-NPs had significant anticancer potential, induction of apoptosis and higher uptake compared to pure SBN. Thus, prepared Biotin@SBN-BSA-NPs could be a potential targeted drug delivery system for hydrophobic anticancer bioactive compounds like SBN.

Toward the Controlled Synthesis of Lead Halide Perovskite Nanocrystals.

Lead halide perovskite nanocrystals (LHP NCs) have rapidly emerged as one of the most promising materials for optical sources, photovoltaics, and sensor fields. The controlled synthesis of LHP NCs with high monodispersity and precise size tunability has been a subject of intensive research in recent years. However, due to their ionic nature, LHP NCs are usually formed instantaneously, and the corresponding nucleation and growth are difficult to monitor and regulated. In this Perspective, we summarize the representative attempts to achieve controlled synthesis of LHP NCs. We first highlight the burst nucleation and rapid growth characteristics of conventional synthesis methods. Afterward, we introduce the scheme of changing the LHP NCs into kinetically dominant, continuously size-tunable synthesis via nucleation-growth decoupling. We also summarize methods to eliminate undesired ripening effects and achieve homogeneous size distribution through rational ligand selection and solvent engineering. We hope this Perspective will facilitate the development of controlled LHP NCs synthesis protocols and advance the understanding of crystal growth fundamentals of perovskite materials.

Identifying synergistic combinations of Doxorubicin-Loaded polyquercetin nanoparticles and natural Products: Implications for breast cancer therapy

Combining chemotherapeutic agents with bioactive natural products is an attractive cancer treatment modality to reduce the dose and side effects of chemotherapy. Combination treatments with drugs having different mechanisms of action can also be beneficial in combatting the development of drug resistance by cancer cells. Nanoparticle (NP)-mediated drug delivery can further improve the therapeutic index of cytotoxic agents by enabling passive and/or active targeting to tumor tissues in vivo. Using doxorubicin (DOX) as a model chemotherapeutic agent, we developed three NP formulations based on polyquercetin (pQCT), an emerging nanocarrier platform. The NPs were co-assembled with DOX, pQCT, and either Pluronic P123, methoxy poly(ethylene glycol)-amine, or D-α-tocopheryl poly(ethylene glycol) 1000 succinate (TPGS). Physicochemical characterization of the NPs revealed them to have a spherical morphology with high monodispersity, excellent drug loading capacity, and sustained drug release. Then, the NPs were evaluated in vitro to determine their potential synergism when combined with the bioactive natural products curcumin (CUR), tannic acid (TA), and thymoquinone (TQ) against breast cancer cells (MCF-7 and MDA-MB-231). Surprisingly, most of the combinations were found to be antagonistic. However, combinations containing CUR exhibited greater pro-apoptotic effects compared to the single agents, with polymer-modified pQCT NPs presenting as a promising nanoplatform for enhancing DOX’s ability to promote cancer cell apoptosis. Our findings provide insights into the potential application of pQCT in nanomedicine, as well as the use of bioactive natural products in combination with DOX as a free agent and as an NP formulation in the treatment of breast cancer.