Precise Size Control Research Articles

Optimization of large-scale manufacturing of biopolymeric and lipid nanoparticles using microfluidic swirl mixers

Nanoparticles (NPs) have great potential as efficient drug delivery systems (DDSs) that have been widely used in cancer therapy and vaccines especially in the past decade. The rise in demand from the pharmaceutical industry drives the growth of the global NPs market. However, complex production processes have hindered the market growth. Therefore, the development of advanced preparation techniques such as microfluidics is required to improve productivity and controllability. In this study, we present a novel microfluidic design (swirl mixer) that helps accelerating the translation of many DDSs from laboratory to clinical application. The new swirl mixer provides high production rate, reproducibility, and precise control of particle size with low polydispersity index (PDI). To assess the performance of the swirl mixer, two different types of nanoformulations were used: silk nanoparticles (SNPs) and lipid nanoparticles (LNPs). The microfluidic device produced NPs efficiently with high productivity and allowed for tuning the mean size and size distribution by changing multiple processing parameters.

Precise Control of Microcapillary Size in Microcapillary Films by Liquid‐Assisted Extrusion

AbstractMicrocapillary films (MCFs) are plastic films with an array of microcapillaries, which have been widely applied in microfluidics and bioanalytical techniques. However, the precise control of microcapillary size is still a problem hindering the industrial applications of MCFs because the high size uniformity of microcapillaries ensures the production of homogeneous droplets and the robust performance of immunoassays. Here, a novel approach is provided to precisely adjust the size of microcapillaries by liquid‐assisted extrusion and to investigate the combined effects of extrusion, drawing and liquid injection on the microcapillary size. Compared with gas‐assisted extrusion, the size uniformity is improved by at least 5% for 89% experiments and 10% for 42% experiments. Therefore, this method facilitates MCFs’ applications in droplet microfluidics and biotechnologies.

Fabrication of Size-Controlled and Emulsion-Free Chitosan-Genipin Microgels for Tissue Engineering Applications.

Chitosan microgels are of significant interest in tissue engineering due to their wide range of applications, low cost, and immunogenicity. However, chitosan microgels are commonly fabricated using emulsion methods that require organic solvent rinses, which are toxic and harmful to the environment. The present protocol presents a rapid, non-cytotoxic, non-emulsion-based method for fabricating chitosan-genipin microgels without the need for organic solvent rinses. The microgels described herein can be fabricated with precise size control. They exhibit sustained release of biomolecules, making them highly relevant for tissue engineering, biomaterials, and regenerative medicine. Chitosan is crosslinked with genipin to form a hydrogel network, then passed through a syringe filter to produce the microgels. The microgels can be filtered to create a range of sizes, and they show pH-dependent swelling and degrade over time enzymatically. These microgels have been employed in a rat growth plate injury model and were demonstrated to promote increased cartilage tissue repair and to show complete degradation at 28 days in vivo. Due to their low cost, high convenience, and ease of fabrication with cytocompatible materials, these chitosan microgels present an exciting and unique technology in tissue engineering.

Comparison of Hydrogen Peroxide Secretion From Living Cells Cultured in Different Formats Using Hydrogel-Based LSPR Substrates.

Reactive oxygen species (ROS), a number of reactive molecules and free radicals derived from molecular oxygen, are generated as by-products during mitochondrial electron transport within cells. Physiologically, cells are capable of metabolizing the ROS exploiting specific mechanisms. However, if excessive ROS accumulate inside the cells, it will cause the cells apoptosis or necrosis. Hydrogen peroxide (H2O2) is one of the essential ROS often participating in chemical reactions in organisms and regulating homeostasis in the body. Therefore, rapid and sensitive detection of H2O2 is a significant task in cell biology research. Furthermore, it has been found that cells cultured in different formats can result in different cellular responses and biological activities. In order to investigate the H2O2 secretion from the cells cultured in different formats, a hydrogel-based substrate is exploited to separate relatively large molecular (e.g., proteins) for direct measurement of H2O2 secreted from living cells in complete cell culture medium containing serum. The substrate takes advantage of the localized surface plasmon resonance (LSPR) method based on enzyme immunoprecipitation. In addition, the H2O2 secreted from the cells cultured in different dimensions (suspension of single cells and three-dimensional cell spheroids) treated with identical drugs is measured and compared. The spheroid samples can be prepared with ample amount using a designed microfluidic device with precise control of size. The results show that the H2O2 secretion from the cells are great affected by their culture formats.

Production of siRNA-Loaded Lipid Nanoparticles using a Microfluidic Device

The development of functional lipid nanoparticles (LNPs) is one of the major challenges in the field of drug delivery systems (DDS). Recently, LNP-based RNA delivery systems, namely, RNA-loaded LNPs have attracted attention for RNA therapy. In particular, mRNA-loaded LNP vaccines were approved to prevent COVID-19, thereby leading to the paradigm shift toward the development of next-generation nanomedicines. For the LNP-based nanomedicines, the LNP size is a significant factor in controlling the LNP biodistribution and LNP performance. Therefore, a precise LNP size control technique is indispensable for the LNP production process. Here, we report a protocol for size controlled LNP production using a microfluidic device, named iLiNP. siRNA loaded LNPs are also produced using the iLiNP device and evaluated by in vitro experiment. Representative results are shown for the LNP size, including siRNA-loaded LNPs, Z-potential, siRNA encapsulation efficiency, cytotoxicity, and target gene silencing activity.

Production of siRNA-Loaded Lipid Nanoparticles using a Microfluidic Device.

The development of functional lipid nanoparticles (LNPs) is one of the major challenges in the field of drug delivery systems (DDS). Recently, LNP-based RNA delivery systems, namely, RNA-loaded LNPs have attracted attention for RNA therapy. In particular, mRNA-loaded LNP vaccines were approved to prevent COVID-19, thereby leading to the paradigm shift toward the development of next-generation nanomedicines. For the LNP-based nanomedicines, the LNP size is a significant factor in controlling the LNP biodistribution and LNP performance. Therefore, a precise LNP size control technique is indispensable for the LNP production process. Here, we report a protocol for size controlled LNP production using a microfluidic device, named iLiNP. siRNA loaded LNPs are also produced using the iLiNP device and evaluated by in vitro experiment. Representative results are shown for the LNP size, including siRNA-loaded LNPs, Z-potential, siRNA encapsulation efficiency, cytotoxicity, and target gene silencing activity.

Shape-specific microfabricated particles for biomedical applications: a review

The storied history of controlled the release systems has evolved over time; from degradable drug-loaded sutures to monolithic zero-ordered release devices and nano-sized drug delivery formulations. Scientists have tuned the physico-chemical properties of these drug carriers to optimize their performance in biomedical/pharmaceutical applications. In particular, particle drug delivery systems at the micron size regime have been used since the 1980s. Recent advances in micro and nanofabrication techniques have enabled precise control of particle size and geometry–here we review the utility of microplates and discoidal polymeric particles for a range of pharmaceutical applications. Microplates are defined as micrometer scale polymeric local depot devices in cuboid form, while discoidal polymeric nanoconstructs are disk-shaped polymeric particles having a cross-sectional diameter in the micrometer range and a thickness in the hundreds of nanometer range. These versatile particles can be used to treat several pathologies such as cancer, inflammatory diseases and vascular diseases, by leveraging their size, shape, physical properties (e.g., stiffness), and component materials, to tune their functionality. This review highlights design and fabrication strategies for these particles, discusses their applications, and elaborates on emerging trends for their use in formulations.Graphical abstract

Synchronous Preparation of Length-Controllable 1D Nanoparticles via Crystallization-Driven In Situ Nanoparticlization of Conjugated Polymers

Precise size control of semiconducting nanomaterials from polymers is crucial for optoelectronic applications, but the low solubility of conjugated polymers makes this challenging. Herein, we prepared length-controlled semiconducting one-dimensional (1D) nanoparticles by synchronous self-assembly during polymerization. First, we succeeded in unprecedented living polymerization of highly soluble conjugated poly(3,4-dihexylthiophene). Then, block copolymerization of poly(3,4-dihexylthiophene)-block-polythiophene spontaneously produced narrow-dispersed 1D nanoparticles with lengths from 15 to 282 nm according to the size of a crystalline polythiophene core. The key factors for high efficiency and length control are a highly solubilizing shell and slow polymerization of the core, thereby favoring nucleation elongation over isodesmic growth. Combining kinetics and high-resolution imaging analyses, we propose a unique mechanism called crystallization-driven in situ nanoparticlization of conjugated polymers (CD-INCP) where spontaneous nucleation creates seeds, followed by seeded growth in units of micelles. Also, we achieved "living" CD-INCP through a chain-extension experiment. We further simplified CD-INCP by adding both monomers together in one-shot copolymerization but still producing length-controlled nanoparticles.

Oligodendrocyte precursor cells sculpt the visual system by regulating axonal remodeling

Many oligodendrocyte precursor cells (OPCs) do not differentiate to form myelin, suggesting additional roles of this cell population. The zebrafish optic tectum contains OPCs in regions devoid of myelin. Elimination of these OPCs impaired precise control of retinal ganglion cell axon arbor size during formation and maturation of retinotectal connectivity and degraded functional processing of visual stimuli. Therefore, OPCs fine-tune neural circuits independently of their canonical role to make myelin.

Fabrication of Functional Polycatechol Nanoparticles.

While low-dimensional (1D and 2D) polycatechol materials have been widely described for a range of biomedical and surface engineering applications, very few examples have been explored that focus on the construction of functional polycatechol nanoparticles. Herein, we report the facile fabrication of a series of polycatechol nanoparticles via a general and robust strategy based on the one-step oxidation reaction. IO3--induced catechol redox chemistry could facilitate the precise size control of the resulting nanoparticles and also allow the successful transfer and amplification of microscopic monomer function into macroscopic polycatechol material properties. The ease, facileness, and controllability of such a one-step fabrication process could highly promote the development of polycatechol nanomaterials for various applications.

Size-Dependent Thermal Stability and Optical Properties of Ultra-Small Nanodiamonds Synthesized under High Pressure.

Diamond properties down to the quantum-size region are still poorly understood. High-pressure high-temperature (HPHT) synthesis from chloroadamantane molecules allows precise control of nanodiamond size. Thermal stability and optical properties of nanodiamonds with sizes spanning range from <1 to 8 nm are investigated. It is shown that the existing hypothesis about enhanced thermal stability of nanodiamonds smaller than 2 nm is incorrect. The most striking feature in IR absorption of these samples is the appearance of an enhanced transmission band near the diamond Raman mode (1332 cm). Following the previously proposed explanation, we attribute this phenomenon to the Fano effect caused by resonance of the diamond Raman mode with continuum of conductive surface states. We assume that these surface states may be formed by reconstruction of broken bonds on the nanodiamond surfaces. This effect is also responsible for the observed asymmetry of Raman scattering peak. The mechanism of nanodiamond formation in HPHT synthesis is proposed, explaining peculiarities of their structure and properties.

Optimal colloidal synthesis and quality judgment of low-dimensional Cs3Cu2Cl5 nanocrystals with efficient green emission

Low-dimensional copper (I)-based ternary metal halides, having the features of nontoxicity, outstanding optical performance and great air-stability, is becoming the promising substitutes for traditional metal perovskite halides. Despite the impressive progress in copper halides, highly effective synthesis of their nanocrystals with precise shape and size control, compared to that of conventional lead halide semiconductors, is still remained to be explored. In this work, we report a systematically optimized finds for the colloidal synthesis conditions of Cs3Cu2Cl5 nanocrystals (NCs). The Cs3Cu2Cl5 NCs are modulated from nanoparticles to nanorods and to nanoplates by adjusting reaction temperature and reaction time. Cs3Cu2Cl5 nanorods give a wide emission at 510 nm, being caused by self-trapped exciton state with exciton binding energy of 137 meV and phonon–electron interaction of 25 meV as determined by temperature-dependent photoluminescence spectra. The photoluminescence quantum yield (PLQY) of the nanorods that were reacted at 150 °C for 1200 s, an optimal reaction condition, reaches up to 80.19%. We also find for the first time that the optical quality of Cs3Cu2Cl5 NCs is positively related to the full width at half maximum of main peak in X-ray diffraction pattern. The findings in this work give a view to the future planning for Cs3Cu2Cl5’s colloidal synthesis and raise an intuitive criterion for the quality of as-synthesized Cs3Cu2Cl5 NCs.

Precise size-control and functionalization of gold nanoparticles synthesized by plasma-liquid interactions: using carboxylic, amino, and thiol ligands.

Using gold nanoparticles (GNPs) in high-standard applications requires GNPs to be fabricated with high-quality size and surface properties. Plasma-liquid interactions (PLIs) have the unique ability to synthesize GNPs without using any reducing agents, and the GNP surface is free of stabilizing agents. It is an extreme advantage that ensures success for the subsequent functionalization processes for GNPs. However, fabricating GNPs via PLIs at the desired size has still been a challenge. Here, we present a simple approach to achieving the precise size-control of GNPs synthesized by PLIs. By adding suitable ligands to the precursor solution, the ligands wrap GNPs which interrupts and slows down the rapid growth of GNPs under PLIs. This way, the size of the GNPs can be precisely controlled by adjusting the ligand concentration. Our results showed that the size of the GNPs in the range of 10-60 nm can be fitted to reciprocal functions of the ligand concentration. The potency of the size-control depends on the type of ligands in the order of thiol > amine > carboxylate. The size-control has been well investigated with four common ligands: l-cysteine, glucosamine, salicylic acid, and terephthalic acid. XPS, FTIR, and zeta potential techniques confirmed the presence of these ligands on GNPs. The results indicated that functionalized ligands could be utilized to control the size and functionalize the GNP surface. Hence our approach could simultaneously achieve two goals: precise size-control and functionalization of GNPs without the ligand-exchange step.

Redispersion strategy for high-loading carbon-supported metal catalysts with controlled nuclearity.

Supported low-nuclearity metal catalysts integrating single atoms or small clusters have emerged as promising materials for diverse applications. While sophisticated synthetic methods provide a high level of nuclearity control in the subnanometre regime, these routes do not fulfil the requirements for translation into industrial practice of (i) effectiveness for high metal contents and (ii) facile scalability. Herein, we present a gas-phase redispersion strategy consisting of sequential C2H2 and HCl treatments to gradually disperse Ru, Rh and Ir nanoparticles supported on commercial activated carbon with metal content up to 10 wt% and initial average sizes of ≈ 1 nm into small clusters and eventually single atoms. Avoidance of nanoparticle surface overchlorination, which hinders C2H2 adsorption, is identified as key for the redispersion process, as demonstrated by the inefficacy of both C2H2–HCl cofeeding and inverse sequence (i.e., HCl first) treatments. Precise size control (±0.1 nm) is enabled by regulating the number of C2H2–HCl cycles. Detailed characterisation by X-ray absorption spectroscopy, electron paramagnetic resonance and time-resolved mass spectrometry reveals that the redispersion occurs via a layer-by-layer mechanism. Specifically, the migration of surface chlorinated metal species to the carbon support is induced by the C2H2 treatment, depleting accessible surface Cl atoms, while the subsequent HCl treatment rechlorinates the cluster surface. The strategy paves the way for the generation of high-density metal sites with tuneable nuclearity for tailored applications.

Silver nano-particles' size prediction using deep learning model with green method

When it comes to casting technologies and other production processes such as welding, DL models minimise the need for costly experimental inquiry. One of the most important criteria in nanotechnology is the measurement of particle size. They've received a lot of interest for their chemical, physical, and clinical uses because of their outstanding qualities. By adopting a green chemical reduction process, the nano-silver crystals are generated in the biopolymer interface without any agglomeration. Nano-metal production relies on precise control of particle size, and this approach provides that. For the prediction size of Ag-NPs via the green approach, a hybrid ideal of Long-Short Term Memory (LSTM) and Convolutional Neural Network (CNN) and model is presented in this research. Temperature, starch stabiliser, and AgNO3 concentration are among the experimental variables fed into the CNN-LSTM model. The size of a nano particle is the output of the CNN-LSTM model. Making three subsets of the experimental data for training, validation, and testing was one of the initial steps in creating an adapting model. The silver nanoparticles were identified using X-ray diffraction and transmission electron microscopy. Ag-NPs' crystallographic airplanes were found to be face-centered cubic, according to XRD analysis (fcc).When comparing with other existing classifiers, DNN achieved high performance on precision, i.e. 89.87%, and this is due to the presence of simple structure. The CNN and auto encoder achieved nearly 82% and 80% of accuracy, where LSTM achieved 77.25% of accuracy and proposed CNN-LSTM achieved 83.50% of recall.

Carbon dots as a ‘green’ reagent to produce shape and size controlled gold nanoparticles for application in pollutant degradation

Gold nanoparticles (Au NPs) have attracted wide attention as catalysts for in situ degradation of organic pollutants. Current synthetic methods that enable precise control of Au NPs size and shape cause adverse effects on the environment. In this work, a sustainable, one-step method was used to synthesize Au NPs by reducing Au3+ with norepinephrine and ethylamine-based carbon dots (NE/EA CDs). CDs not only act as reducing agent but also stabilize the resulting Au NPs. The mechanism of Au3+ reduction was investigated by studying the effects of functional groups present in the CDs, which were confirmed from UV–Vis and XPS spectral analysis. Three different morphologies of Au NPs were observed after reduction: nanotriangles, nanourchins and nanospheres. Fabricated Au NPs were used to study a model catalytic reaction, reduction of 4-nitrophenol, indicating that CDs are an attractive option for fabrication of Au NPs for water treatment applications.

A picket fence function for adherens junctions in epithelial cell polarity.

Adherens junctions are a defining feature of all epithelial cells, providing cell-cell adhesion and contractile ring formation that is essential for cell and tissue morphology. In Drosophila, adherens junctions are concentrated between the apical and basolateral plasma membrane domains, defined by aPKC-Par6-Baz and Lgl/Dlg/Scrib, respectively. Whether adherens junctions contribute to apical-basal polarization itself has been unclear because neuroblasts exhibit apical-basal polarization of aPKC-Par6-Baz and Lgl in the absence of adherens junctions. Here we show that, upon disruption of adherens junctions in epithelial cells, apical polarity determinants such as aPKC can still segregate from basolateral Lgl, but lose their sharp boundaries and also overlap with Dlg and Scrib - similar to neuroblasts. In addition, control of apical versus basolateral domain size is lost, along with control of cell shape, in the absence of adherens junctions. Manipulating the levels of apical Par3/Baz or basolateral Lgl polarity determinants in experiments and in computer simulations confirms that adherens junctions provide a 'picket fence' diffusion barrier that restricts the spread of polarity determinants along the membrane to enable precise domain size control. Movement of adherens junctions in response to mechanical forces during morphogenetic change thus enables spontaneous adjustment of apical versus basolateral domain size as an emergent property of the polarising system.

Microfluidic mixing system for precise PLGA-PEG nanoparticles size control

In this study, a microfluidic device was employed to produce polymeric nanoparticles (NPs) with well-controlled sizes. The influence of several parameters in the synthesis process, namely, polymer concentration, flow rate and flow rate ratio between the aqueous and organic solutions was investigated. To evaluate the NPs size effect, three diameters were selected (30, 50 and 70 nm). Their cytocompatibility was demonstrated on endothelial cells and macrophages. Additionally, their efficacy to act as drug carriers was assessed in an in vitro inflammatory scenario. NPs loaded and released diclofenac (DCF) in a size-dependent profile (smaller sizes presented lower DCF content and higher release rate). Moreover, 30 nm NPs were the most effective in reducing prostaglandin E2 concentration. Therefore, this study demonstrates that microfluidics can generate stable NPs with controlled sizes, high monodispersity and enhanced batch-to-batch reproducibility. Indeed, NPs size is a crucial parameter for drug encapsulation, release and overall biological efficacy.

Influencing factors and size prediction of bubbles formed by flow focusing in a cross-channel

Formation of uniform-sized bubbles in microchannels by gas–liquid two-phase flow is the basis for applications such as microreactors and micro/nano preparation. In this study, a two-phase flow regime was investigated in a cross-channel controlled by the liquid-phase flow rate and gas-phase pressure. The size of the monodisperse bubbles was predicted based on the factors influencing the bubble length obtained from the dimensional analysis. The transition line between flow patterns was calculated using the bubble length prediction equation, and the flow phase diagram of the gas–liquid two-phase flow in the microfluidic channel was completed. The relationship between the inlet conditions, including the gas-phase pressure and liquid-phase flow rate, and the flow pattern in the microchannel was studied in depth. The results are relevant to the design of microbubble production devices and the precise control of bubble size.

Plasmonic Bismuth Nanoparticles: Thiolate Pyrolysis Synthesis, Size-Dependent LSPR Property, and Their Oxidation Behavior.

Plasmonics, especially the localized surface plasmon resonance (LSPR) in non-noble metal bismuth nanoparticles (Bi NPs), and its spectral features and applications have stimulated increasing research interest in recent years. However, the lack of mature methods to prepare Bi NPs with a well-controlled size and/or shape significantly limits the experimental investigations concerning the LSPR optical properties. Herein, we realize the size-tunable synthesis of nearly monodisperse spherical Bi NPs through a thiolate pyrolysis reaction in solution. The instantaneous thermolysis of a layered molecular intermediate, bismuth dodecanethiolate [Bi(SC12H25)3], results in a classical LaMer mechanism for the nucleation and growth of Bi NPs, allowing for a precise size control from 65 to 205 nm in the average diameter. The diameter tunability enables a systematic study on the size dependence of LSPR optical properties of Bi NPs, and we observe rich ultraviolet-visible-near-infrared spectral responses arising from the LSPR absorption and scattering of Bi NPs as their size varies, which will greatly benefit the light harvesting and manipulation in the solar spectrum. Furthermore, we find that a complete oxidation occurs to Bi NPs under air flow at the temperature when they melt and accordingly generate metastable tetragonal-phase β-Bi2O3 NPs that show an optical band gap of 2.15 eV and interesting temperature-dependent β → α → δ → (γ + β) polymorphic transitions.