Synthesis Of Microparticles Research Articles

Synthesis and photophysical behavior of fluorescent benzazole dyes and fluorescent microparticles: Their use as fingerprint developer

Novel benzazole derivatives were synthesized and their photophysical properties were determined experimentally in different types of solvents also by theoretical calculations using Density Functional Theory (DFT). The results of the theoretical computational studies were well consistent with those observed experimentally, evidencing the type of electronic transitions that occurs between the frontiers orbitals. All synthesized derivatives are highly fluorescent in the violet-green region (363–536 nm) under ultraviolet light of 365 nm with large Stokes shift due to excited state intramolecular proton transfer (ESIPT) mechanism. Furthermore, the thermogravimetric and differential thermogravimetric analysis showed their good thermal stability, with decomposition temperature up to 250 °C. The fluorescent benzazole derivative was successfully entrapped into starch-based microparticles and applied for visualization of latent fingerprints on different types of surfaces common to forensic cases (metal, plastic, paper, wood, and ceramic).

Core-shell chiral polymeric-metallic particles obtained in a single step by concurrent light induced processes

Core-shell architecture enables to impart unique customized properties to microparticles, through the proper selection of composition and aggregation state of the inner and outer materials. Here, the synthesis of microparticles with a chiral dielectric core and a metallic shell of gold nanoparticles is demonstrated. The chiral core is obtained by UV induced polymerization of the self-organized droplets of a cholesteric reactive mesogen in a chloroauric acid aqueous solution. Gold nanoparticles precipitation contemporarily occurs upon UV irradiation, covering the microparticles surface. Electron microscopy and optical spectroscopy investigations give evidence that the degree of coverage of the core by gold nanoparticles, with size less than 100 nm, depends on the chloroauric acid concentration, while their aggregation is influenced by the polymeric surface morphology. The optical properties of the chiral microparticles are modified by the gold shell. Specifically, gold coating of dye doped chiral microparticles, working as Bragg onion resonators, clearly improves the stability of omnidirectional microlasers. The proposed strategy, due to the flexibility of the chiral material and of the method, opens a route toward fabrication of microdevices with wide control over light manipulation, in term of intensity, polarization, generation.

Unusual Nanofractal Microparticles for Rapid Protein Capture and Release.

Ion exchange porous microparticles are widely used for protein separation, but their totally porous structure often leads to slow diffusion rate and long separation time. Here unusual nanofractal microparticles synthesized by a strategy of electrostatic interaction regulated emulsion interfacial polymerization are demonstrated that exhibit excellent capability of rapid protein capture, release, and separation. The growth of nanostructures at nanofractal microparticle surface can be controlled by changing electrostatic repulsion between ion groups from weak to strong. The nanofractal microparticles provide a 3D contact model between ion groups and proteins, enable fast protein diffusion rate at initial capture and release stage, and realize rapid and efficient separation of similarly sized proteins as a proof of concept, superior to porous microparticles. This strategy offers an effective and general way for the synthesis of microparticles towards rapid and efficient separation in various fields of biomedicine, environment, and food.

Hybrid silica micro-particles with light-responsive surface properties and Janus-like character

The present work highlights the synthesis and post-modification of silica-based micro-particles containing photo-responsive polymer brushes with photolabile o-nitrobenzyl ester (o-NBE) chromophores.

Sintesis dan Kararkterisasi Modifikasi Mikropartikel Magnetit (Fe3O4) Dalam Pemanfaatan Karat dengan Ekstrak Daun Ilalang (Imperata Cylindrica L)

The synthesis of magnetite (Fe3O4) microparticles has been successfully carried out using rust and leaf extract of grass (Imperata cylindrica L). The purpose of this research is the synthesis and characterization of Fe3O4 microparticles using the Green Synthesis method. The UV-Vis results showed that the absorption peak was at a wavelength of 273 nm with an absorbance value of 0.75. FTIR analysis shows the shift of the peak at wave number 3356 cm-1 to 3290 cm-1 and the appearance of a new peak at wave number 500 cm-1 which is characteristic of the Fe-O-Fe functional group and indicates the formation of Fe3O4 microparticles. XRD results showed six specific peaks, which were crystallinity of Fe3O4 microparticles at position 2 theta 30.40 °, 35.70 °, 43.30 °, 53.80 °, 57.40 °, and 63.00 °. PSA analysis showed that the mean particle size was > 100 nm, and the PZC results showed a zeta potential of 20 mV. SEM results showed the morphology of Fe3O4 microparticles with 1000x magnification, and EDS analysis results showed Fe and O's elemental composition.

Multifunctional CaCO3/polyelectrolyte sorbents for heavy metal ions decontamination of synthetic waters

Herein, new composites were obtained by co-precipitation of complementary polyions (poly(acrylic acid) (PAA), linear and branched poly(ethyleneimine) (PEIL and PEIB)) and CaCO3 crystallization from supersaturated solutions at pH ∼ 10.5. Using the step-by-step adsorption protocol, PEI or its Cu complexes and PAA were alternately adsorbed and cross-linked onto CaCO3-based microparticles. The sorption properties for Cu(II), Co(II) and Ni(II) by CaCO3 microparticles with morphology and chemical structure controlled by the polymer presence in the microparticles synthesis environment and by the step-by-step polycation/polyanion sorption, were deeply investigated. This study aims to improve the knowledge of CaCO3 formation in the presence of different macromolecules and provides an understanding of the crystal-structure-related adsorption properties of CaCO3 giving a guidance for designing CaCO3-based sorbent, efficient, and environmentally friendly for decontamination of synthetic waters.

Are reported methods for synthesizing nanoparticles and microparticles by magnetic stirrer reproducible

One of the most common tools for fabricating different drug-loaded polymeric particles is magnetic stirrer, a widely-used tool in nano-based drug delivery systems. Typically, the revolutions per minute (rpm) or G-Force of the stirrer are reported in related literature, while other parameters generate less attention and must be better understood. Reporting the rpm or G-Force is likely insufficient for producing the same vortex flow intensity and mono-dispersity as having a reliable and reproducible nanoparticle and microparticle synthesis method. We speculate that the magnetic stirrer bar’s length and diameter, and the size of the cylindrical container, affect the qualities of nanoparticles and microparticles. Given the importance of these particle characteristics in the field of nanomedicine, understanding these details would improve reporting method reliability. These data are currently missing in most related papers and must be reported. The purpose of our study is to highlight the importance of these underestimated parameters (magnetic bar’s length, diameter, and the size of the cylindrical container) and the impact on the reproducibility of particle synthesis methods using a magnetic stirrer.

Discontinuous Dewetting in a Degassed Mold for Fabrication of Homogeneous Polymeric Microparticles.

Discontinuous dewetting (DD) is an attractive technique that enables the production of large liquid arrays in microwells and is applicable to the synthesis of anisotropic microparticles with complex morphologies. However, such loading of liquids into microwells presents a significant challenge, as the liquids used in this technique should exhibit low mold surface wettability. This study introduces DD in a degassed mold (DM), a simple yet powerful technique that achieves uniform loading of microparticle precursors into large microwell arrays within 1 min. Using this technique, hydrogel microparticles are produced by different polymerization mechanisms with various shapes and sizes, ranging from a few micrometers to hundreds of micrometers. Hydrophobic oil microparticles are produced by the simple plasma treatment of the DM, and agarose microparticles encapsulating bovine serum albumin (in a well-dispersed state) are produced by submerging the DM in fluorinated oil. To demonstrate additional functionality of microparticles using this technique, high concentrations of magnetic nanoparticles are loaded into microparticles for particle-based immunoassays performed in a microwell plate, and the immunoassay performance is comparable to that of ELISA.

Scalable and Recyclable All-Organic Colloidal Cascade Catalysts.

We report on the synthesis of core–shell microparticles (CSMs) with an acid catalyst in the core and a base catalyst in the shell by surfactant‐free emulsion polymerization (SFEP). The organocatalytic monomers were separately copolymerized in three synthetic steps allowing the spatial separation of incompatible acid and base catalysts within the CSMs. Importantly, a protected and thermo‐decomposable sulfonate monomer was used as acid source to circumvent the neutralization of the base catalyst during shell formation, which was key to obtain stable, catalytically active CSMs. The catalysts showed excellent performance in an established one‐pot model cascade reaction in various solvents (including water), which involved an acid‐catalyzed deacetalization followed by a base‐catalyzed Knoevenagel condensation. The CSMs are easily recycled, modified, and their synthesis is scalable, making them promising candidates for organocatalytic applications.

Functional microparticles from multiscale regulation of multiphase emulsions for mass-transfer intensification

Mass transfer of pollutants and drugs in microparticles are important for their applications in the fields of water decontamination and drug delivery. Microparticles with controllable structures and advanced functions allow enhancement of mass transfer processes to achieve improved performances for water decontamination and drug delivery. This review summarizes recent progresses on controllable fabrication of functional microparticles from microfluidic multiphase emulsions, with intensified mass-transfer for water decontamination and drug delivery. This is started by introducing the controllable microfluidic production of diverse monodisperse emulsions, and then the template synthesis of functional microparticles from the emulsion templates for water decontamination and drug delivery. Porous microparticles with intensified mass transfer via creation of hierarchical pores and bubble-propelled motion for enhanced water decontamination are introduced. Then, compartmental microparticles with intensified mass transfer via shell permeability adjustment, shell degradation, shell shrinkage, and their combinations for advanced drug delivery are highlighted. The strategies to engineer the functional microparticles for intensified mass transfer via multiscale regulation of their multiphase emulsion templates are emphasized. Finally, perspectives on the future development of microfluidic techniques for developing advanced functional microparticles with intensified mass transfer for enhanced performances are discussed.

Optimisation of the green synthesis of Cu/Cu2O particles for maximum yield production and reduced oxidation for electronic applications

Taguchi method with an L8 orthogonal array and analysis of variance (ANOVA) were used to evaluate the effect of pH, amount of Cynara scolymus L.(artichoke) extract (AE), copper salt concentration (SC) and temperature (T) on the optimization of green synthesis of copper microparticles with respect to the maximization of the yield production and, for the first time, with respect to the minimization of the oxidation degree of the copper microparticles. Results indicate that pH and AE have greater influence on the Cu/Cu2O microparticles yield. While the pH, AE and T have greater influence on the oxidation degree of the Cu/Cu2O microparticles. XRD confirmed the minimization of Cu2O phase over Cu/Cu2O mixture, reducing Cu2O from 83% to 31%. Spherical particles of 324–711 nm were observed and the electrical resistivity of Cu/Cu2O (69/31 wt%) was 1.52 × 10 −3 Ω.cm.

Synthesis of monetite micro particles from egg shell waste and study of its environmental applications: Fuel additive and catalyst

Monetite is used in water decontamination and fuel additive due to less toxic, easy and cheap synthesis approach. Egg shell is used as precursor along with disodium phosphate for synthesis of monetite particles. Composition, phase and purity of the product are analyzed by X-ray diffraction spectroscopy. Bond angles and bond lengths of the polyhedra constituted by phosphorus and oxygen species are calculated. The morphology of particles is analyzed, and size is measured with the help of scanning electron microscopy and transmission electron microscopy. Monetite is used as catalyst for degradation of Congo red dye, a carcinogenic dye. Effect of catalyst dosage on apparent rate constant is investigated and results are compared with literature to analyze the catalytic property of monetite particles. Monetite is also used as additive for diesel fuel. Calorific value and other parameters are measured and effect of additive on efficiency of fuel is analyzed. Monetite is a promising catalyst because kapp value is increased from 0.0077 to 0.00114 min−1 by increasing catalyst dosage from 1.0 to 2.5 mg/mL. It is also a good additive because calorific value is increased from 2.55 to 8.902 MJ/kg with increase in additive dosage from 10 to 40 ppm.

Magnetically Collectable Nanocellulose-Coated Polymer Microparticles by Emulsion Templating.

Magnetic nano/microparticles offer potential benefits for environmental applications such as water purification. However, achieving functional and stable surfaces remains a critical challenge for magnetic particle design. Nanocellulose, a naturally occurring nanofiber, is a promising surface material candidate, owing to its ease of functionalization and chemical stability. Here, we developed a magnetically collectable nanocellulose-coated polymer microparticle synthesis method, based on Pickering emulsion templating. The average diameter of the core/shell microparticles was 2.7 μm, and they were well dispersed in water, owing to the coverage with surface-carboxylated nanocelluloses. Most magnetic Fe3O4 nanoparticles with a 30 nm diameter were encapsulated in the microparticles and enriched at the CNF/polymer interfaces. The nanocellulose shell showed high loading of cationic dye molecules. In addition, the nanocellulose-coated microparticles could be recovered even after the dye loading by exposing the aqueous dispersion to a magnetic field.

One-pot fabrication of uniform half-moon-shaped biodegradable microparticles via microfluidic approach

Engineering of physical parameters such as shape and texture of microparticle can provide solutions to overcome limitations of conventional microparticles. We demonstrate the fabrication of uniform half-moon-shaped microparticles using synthesized poly(d,l-lactide) via a tube-type microfluidic approach. A true half-moon appearance, which comprises of dimple patterns on a round surface and a plain flat surface, is obtained by the optimization of fabrication conditions and a new self-rupturing mechanism. A new pop out mechanism allows for the one-pot synthesis of microparticles with complicated structures. The microparticles can have promising applications such as suspension cell culture, injectable cell carrier, and inhalable particulate drug delivery system because of their excellent cell adhesion, low weight resulting from an internal porous structure, and biodegradable character.

A versatile route to the synthesis of pressure-sensitive adhesives and polyHIPE-like microparticles: an experimental study on glycerol valorization

This present work focuses on the synthesis of styrene / n-acylglycerol (n-ACG) (a macromonomer formed by glycerol esterification with acrylic acid catalyzed by methane sulfonic acid) copolymers through suspension polymerization process. The final properties of poly(styrene-co-n-acylglycerol) was strongly dependent on the n-ACG fraction into the polymer chains. The effect of n-ACG on the copolymer properties was evaluated and a huge reduction in both the thermal stability and the Tg values (from 93 °C for polystyrene homopolymer to −22 °C for styrene / n-ACG copolymers synthesized with 20 wt% of n-ACG) was observed when the n-ACG fraction was increased. The variations in the thermal properties were accompanied by drastic morphological changes of the materials, depending essentially on the n-ACG composition as for instance: i) porous spherical particles with polyHIPE-like structures (copolymers containing from 5 to 15 wt% of n-ACG), which indicates that these porous microparticles may be used as support/carries in heterogeneous catalysis, ion exchange resins, and controlled drug delivery, among others; ii) adhesive films containing n-ACG fractions higher than 15 wt%, conferring "tack" features similar to the one observed in for pressure-sensitive adhesives (PSA) evaluated by using a rolling ball test. Mechanical tests also showed that the polymer adhesives have an enormous potential to be used as PSA materials in the adhesive industry.

Single crystal synthesis of nickel micro-particles with effective involvement of surfactants

Single-crystal nickel micro-particles have been synthesized using oleylamine which perform both functions, as solvent and as reductant, along with nickel nitrate hexahydrate as the metallic salt and C-TAB as a surfactant. SEM imaging and X-ray techniques were used to confirm the presence of the single-crystal structure of nickel micro-particles. The effect of crystallinity on field-based and especially temperature based magnetic properties resulting in higher curie temperatures of nickel micro-particles was also analyzed. Their morphology and magnetic properties were compared with commercially obtained nickel micro-particles and a variety of other nickel microparticles prepared by using different surfactants in the same system.

Factorial design optimization of polystyrene microspheres obtained by aqueous dispersion polymerization in the presence of poly(2‐ethyl‐2‐oxazoline) reactive stabilizer

AbstractThe present study highlights the use of statistical design to establish an effective model for the synthesis of polystyrene microspheres by aqueous dispersion polymerization using poly(2‐ethyl‐2‐oxazoline) reactive stabilizer. The significant parameters (e.g. solvent polarity, stabilizer and initiator concentration) influencing the characteristic responses of the process such as yield, particle size and size distribution, as well as the interactions between the variables, were identified. The macromonomer concentration and solvent polarity influence both particle size and size distribution, whereas initiator concentration influences the yield. Analysis of the variance of process variables indicates that the models can be successfully used to describe the dispersion polymerization process. Moreover, the factorial design allows the development of microspheres with optimal properties with respect to size and size distribution. The experimental data regarding yield, particle size and size distribution of the optimized dispersion polymerization shows less than 7% difference compared with the predicted responses. In view of these results, the implementation of statistical design models represents an efficient solution for optimizing microparticle synthesis while aiming for industrial applications. © 2020 Society of Chemical Industry

Synthesis of Chitin Nanofiber-Coated Polymer Microparticles via Pickering Emulsion.

Chitin nanofiber (ChNF) has received significant research attention owing to its potential for use in a variety of applications, such as medicine and cosmetics. Here, we synthesize a novel ChNF material, ChNF-coated polymer microparticles, using a Pickering emulsion-templated approach. Two varieties of ChNF with different crystal structures, lengths, and surface charges were used to form the microparticle shells. When ChNFs with a shorter length and greater surface charge were used, the microparticles showed good dispersibility in water and narrow size distribution with number- and volume-median diameters of 1.46 and 1.84 μm, respectively. The microparticles were easily collected by filtration and redispersed in water, even after drying. The surface ChNF shells assembled at the microparticle surfaces showed potential as an adsorption site, effectively capturing anionic dye molecules. This technique offers new opportunities for the development of green nanocomposite materials using a facile aqueous process.

First synthesis of monodispersed microparticles of copper oxide films by pulsed spray pyrolysis (PSP): structural, optical, and morphological investigations

This work describes the first synthesis of monodispersed systems by capitalizing on the Leidenfrost effect. We report herein the synthesis of monodispersed particles of copper oxide films by spray pyrolysis technique in pulsed mode. The aim of this work is to investigate the effect of different pulse sequences on the particles’ size. One pulse sequence consists of three spray-on durations $$\tau_{{{\text{on}}}}^{{{\text{spray}}}}$$ separated by two spray-off $$\tau_{{{\text{off}}}}^{{{\text{spray}}}}$$ time intervals. In this work, we have varied the $$\tau_{{{\text{off}}}}^{{{\text{spray}}}}$$ duration from 15 to 45 s by a step of 10 s and the spray-on period is kept constant on 15 s. The effect of the spray-off duration on structural, optical and morphological properties of copper oxide material is reported. Indeed, the obtained films are characterized by XRD, spectrophotometer, Raman spectroscopy, AFM, and SEM. It was revealed that the spray-off duration has a great impact on the copper oxide particles’ size.

Facile synthesis of anhydrous microparticles using plug-and-play microfluidic reactors

Microfluidic materials synthesis techniques are an ideal approach for controlled synthesis of anhydrous microparticles. In this article, we highlight the recent developments using plug-and-play microreactors for anhydrous microparticle synthesis.