Preparation and application of new monosized polymer particles

Shaped Magnetogel Microparticles for Multispectral Magnetic Resonance Contrast and Sensing

Multispectral magnetic resonance imaging (MRI) contrast agents are microfabricated three-dimensional magnetic structures that encode nearby water protons with discrete frequencies. The agents have a unique radiofrequency (RF) resonance that can be tuned by engineering the geometric parameters of these microstructures. Multispectral contrast agents can be used as sensors by incorporating a stimulus-driven shape-changing response into their structure. These geometrically encoded magnetic sensors (GEMS) enable MRI-based sensing via environmentally induced changes to their geometry and their corresponding RF resonance. Previously, GEMS have been made using thin-film lithography techniques in a cleanroom environment. While these approaches offer precise control of the microstructure, they can be a limitation for researchers who do not have cleanroom access or microfabrication expertise. Here, an alternative approach for GEMS fabrication based on soft lithography is introduced. The fabrication scheme uses cheap, accessible materials and simple chemistry to produce shaped magnetic hydrogel microparticles with multispectral MRI contrast properties. The microparticles can be used as sensors by fabricating them out of shape-reconfigurable, "smart" hydrogels. The change in shape causes a corresponding shift in the resonance of the GEMS, producing an MRI-addressable readout of the microenvironment. Proof-of-principle experiments showing a multispectral response to pH change with cylindrical shell-shaped magnetogel GEMS are presented.

Magnetic Dendritic Polymer Nanospheres for High-Performance Separation of Histidine-Rich Proteins

Magnetic nanospheres are becoming a promising platform for a wide range of applications in pharmacy, life science, and immunodiagnostics due to their high surface area, ease of synthesis and manipulation, fast separation, good biocompatibility, and recyclable performance. In this work, an innovative and efficient method is developed by in situ reducing and growing Ni(OH)₂ for the preparation of dendritic mesoporous nanocomposites of silica@Fe₃O₄/tannic acid@nickel hydroxide (dSiO₂@Fe₃O₄/TA@Ni(OH)₂). The flower-like nanospheres have good magnetic response, large surface area, and high histidine-rich protein (His-protein) purification performance. The dSiO₂@Fe₃O₄/TA@Ni(OH)₂ nanospheres were synthesized on the basis of a φ(NaSal/CTAB) of 1/1 and a mass of ferrous chloride tetrahydrate of 0.3 g, resulting in a saturation magnetization value of 48.21 emu/g, which means it can be collected within ∼1 min using a magnetic stand. Also, the BET test showed that the surface area is 92.47 m²/g and the pore size is ∼3.9 nm for dSiO₂@Fe₃O₄/TA@Ni(OH)₂ nanocomposites. Notably, the nickel hydroxide with unique flower-like structural features enables the combination of a large number of Ni²⁺ ions and His-proteins for high performance. The isolation and purification experiments of the synthesized dSiO₂@Fe₃O₄/TA@Ni(OH)₂ were performed by separating His-proteins from a matrix composed of bovine hemoglobin (BHb), bovine serum albumin (BSA), and lysozyme (LYZ). The result showed that the nanospheres have a high combination capacity of ∼1880 mg/g in a rapid equilibrium time of 20 min, which was selective for the adsorption of BHb. In addition, the stability and recyclability of BHb are 80% after seven cycles. Furthermore, the nanospheres were also used to isolate His-proteins from fetal bovine serum, proving its utility. Therefore, the strategy of separating and purifying His-proteins using dSiO₂@Fe₃O₄/TA@Ni(OH)₂ nanospheres is promising for practical applications.

Two Sides of the Same Coin: Light as a Tool to Control and Map Microsphere Design

Herein, we establish the effect of intensity and wavelength on the size of microparticles formed via precipitation polymerization, employing photocrosslinkable prepolymers. Simultaneous measurement of backscattered laser irradiation enabled real-time tracking of particle growth and provides the ability to vary the LED intensity (λ_max = 415 nm) during various stages of particle growth. Critically, particle diameters can be controlled between 200 and 700 nm by varying the LED power from 73 to 0.63 mW, respectively. High intensities during the nucleation phase-spanning only the initial seconds-were found to dictate the particle diameter, irrespective of the energy used during the growth phase. Finally, a bathochromic shift was observed between the wavelength generating the highest rate of particle formation and the absorbance maxima of the photoactive group. We submit that these findings are broadly applicable in the continuously developing field of photoinitiated synthesis of polymer particles.

Magnetic Nanoparticles in Biology and Medicine: Past, Present, and Future Trends

The use of magnetism in medicine has changed dramatically since its first application by the ancient Greeks in 624 BC. Now, by leveraging magnetic nanoparticles, investigators have developed a range of modern applications that use external magnetic fields to manipulate biological systems. Drug delivery systems that incorporate these particles can target therapeutics to specific tissues without the need for biological or chemical cues. Once precisely located within an organism, magnetic nanoparticles can be heated by oscillating magnetic fields, which results in localized inductive heating that can be used for thermal ablation or more subtle cellular manipulation. Biological imaging can also be improved using magnetic nanoparticles as contrast agents; several types of iron oxide nanoparticles are US Food and Drug Administration (FDA)-approved for use in magnetic resonance imaging (MRI) as contrast agents that can improve image resolution and information content. New imaging modalities, such as magnetic particle imaging (MPI), directly detect magnetic nanoparticles within organisms, allowing for background-free imaging of magnetic particle transport and collection. "Lab-on-a-chip" technology benefits from the increased control that magnetic nanoparticles provide over separation, leading to improved cellular separation. Magnetic separation is also becoming important in next-generation immunoassays, in which particles are used to both increase sensitivity and enable multiple analyte detection. More recently, the ability to manipulate material motion with external fields has been applied in magnetically actuated soft robotics that are designed for biomedical interventions. In this review article, the origins of these various areas are introduced, followed by a discussion of current clinical applications, as well as emerging trends in the study and application of these materials.

Unique Oil-in-Brine Pickering Emulsion Using Responsive Antipolyelectrolyte Functionalized Latex: A Versatile Emulsion Stabilizer

A simple and straightforward approach to synthesize oil-in-water (O/W) emulsions under high salinity and temperature using zwitterion-functionalized latexes are presented in this work. First, well-defined functionalized latexes were synthesized by emulsifier-free emulsion copolymerization in the presence of precursor sulfobetaine comonomer using brine as a continuous phase. The surface-functionalized latex particles were then characterized by DLS, SEM, TEM, XPS, and TGA. The functionalized latex exhibited antipolyelectrolyte behavior in high salinity brine and at high temperatures. The effects of salinity, temperature, and pH on the long-term stability of the particles were investigated. Further, to evaluate the potential in high salinity brine and high temperature, the saltphilic functionalized latexes were utilized to stabilize the oil/brine (O/W) interface without any other additives. The latex enabled the formation of a stable Pickering emulsion system with low solid content (<0.02% w/w) in the presence of 50% v/v n-decane. The functionalized latexes were self-assembled at the O/W interface as a spherical colloidosome in high salinity brine through hydrophobic interactions and irreversible adsorption. The supraparticles were imaged with SEM, providing an insight that the exterior of the emulsion droplets is stabilized by the saltphilic latex particles, forming a protective layer at the oil-water interface through electrostatic repulsion. The antipolyelectrolyte latex can be utilized as a novel emulsion stabilizer, which can provide a versatile alternative for applications in a complex environment such as high salinity, temperature, and low or high pH.

On-demand acid-gated fluorescence switch-on in photo-generated nanospheres

Polymer particles are synthesized using a photo-activeortho-methyl benzaldehyde with a terminal alkyne for cross-linking. The reactive 1,4-dihydronaphthalene at every cross-linking point undergoes aromatisation to a fluorescent naphthalene upon exposure to acid.

Synthesis and characterization of antibacterial magnetite-activated carbon nanoparticles

Magnetite iron oxide nanoparticles synthesized using the co-precipitation methods were further functionalized with activated carbon. The magnetite-activated carbon nanoparticles were characterized by scanning electron microscopy equipped with energy dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and UV-Vis spectroscopy. X-ray diffraction and Fourier transform infrared confirmed the functionalization of the Fe3O4 nanoparticles with the activated carbon. The X-ray diffraction studies demonstrate that magnetite-activated carbon nanoparticles were indexed into the spinel cubic lattice with a lattice parameter of 0.833 nm and an average particle size of about 14 nm. Various parameters such as dislocation density, microstrain, and surface morphological studies were calculated. However, this work implicated the use of magnetite-activated carbon nanoparticles in antibacterial studies. Further, the antibacterial effect of magnetite-activated carbon nanoparticles was evaluated against three pathogenic bacteria, which showed that the nanoparticles have moderate antibacterial activity against both Gram-positive ( Staphylococcus aureus) and Gram-negative ( Proteus mirabilis and Pseudomonas aureginosa) pathogenic bacterial strains in the presence of different magnetite-activated carbon nanoparticle concentrations at room temperature.

Colloidal Stabilizer-Assisted Polymerization-Induced Precipitation Method for Colloidally Stable Polyacid Particles

Near-monodispersed, colloidally stable, submicrometer-sized poly(acid phosphoxy ethyl methacrylate) (PAPEMA) latex particles were synthesized by free-radical dispersion polymerization using poly( N-vinylpyrrolidone) (PNVP) as both a steric colloidal stabilizer and a precipitating agent. Polymerization in the absence of PNVP led to a homogeneous transparent solution of PAPEMA, which indicates that the PNVP is essential for latex formation and the complex of PNVP and PAPEMA was formed during the dispersion polymerization. Dispersion copolymerizations with a divinyl cross-linking comonomer (∼20 wt % based on acid phosphoxy ethyl methacrylate) were also successful in synthesizing near-monodispersed, colloidally stable cross-linked PAPEMA latex particles, and the softness and p K_a values of the resulting PAPEMA latex particles can be controlled by varying the divinyl comonomer concentration. These sterically stabilized latex particles were characterized by electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy, elemental microanalysis, and Fourier transform infrared spectroscopy. Characterization results indicated that the PNVP colloidal stabilizer was likely to be located homogeneously on the particle surfaces and within the interior of particles. Finally, it was demonstrated that the PAPEMA latex particles worked as an effective surface modifier for metal surfaces.

Modern Approach to Medical Diagnostics - the Use of Separation Techniques in Microorganisms Detection

Background:

Analytical chemistry and biotechnology as an interdisciplinary fields of science have been developed during many years and are experiencing significant growth, to cover a wide range of microorganisms separation techniques and methods, utilized for medical therapeutic and diagnostic purposes. Currently scientific reports contribute by introducing electrophoretical and immunological methods and formation of devices applied in food protection (avoiding epidemiological diseases) and healthcare (safety ensuring in hospitals).

Methods:

Electrophoretic as well as nucleic-acid-based or specific immunological methods have contributed tremendously to the advance of analyses in recent three decades, particularly in relation to bacteria, viruses and fungi identifications, especially in medical in vitro diagnostics, as well as in environmental or food protection.

Results:

The paper presents the pathogen detection competitiveness of these methods against conventional ones, which are still too time consuming and also labor intensive. The review is presented in several parts following the current trends in improved pathogens separation and detection methods and their subsequent use in medical diagnosis.

Discussion:

Part one, consists of elemental knowledge about microorganisms as an introduction to their characterization: descriptions of divisions, sizes, membranes (cells) components. Second section includes the development, new technological and practical solution descriptions used in electrophoretical procedures during microbes analyses, with special attention paid to bio-samples analyses like blood, urine, lymph or wastewater. Third part covers biomolecular areas that have created a basis needed to identify the progress, limitations and challenges of nucleic-acid-based and immunological techniques discussed to emphasize the advantages of new separative techniques in selective fractionating of microorganisms.

Rapid Self-Assembly of Au Nanoparticles on Rigid Mesoporous Yeast-Based Microspheres for Sensitive Immunoassay

A simple, rapid, inexpensive, eco-friendly, and high-throughput biological strategy for the preparation of functional microspheres on a yeast-cell platform was introduced. Microspheres prepared through the treatment of yeast cells with formaldehyde and decoating buffer exhibited excellent characteristics, such as superior mechanical strength, high sulfhydryl group content, and mesoporous structure. Au nanoparticles (NPs) easily and rapidly self-assembled onto the surfaces of the yeast-based microspheres within 5 min to form rigid yeast@Au microspheres with high monodispersity and uniformity. The rapid formation of yeast@Au microspheres mainly involved the enhancement of sulfhydryl groups and mesoporosity. The yeast@Au microspheres were successfully used in a flow cytometry immunoassay to detect Pseudorabies viral infection events. Signal-to-noise ratio was enhanced by approximately 49.4-fold. The presence of Au NPs on the yeast-based microspheres greatly improved sensitivity by decreasing noise through reducing nonspecific adsorption, highly enhancing the fluorescence signal caused by the surface plasmon resonance effect, and increasing the coupling efficiency of the capture protein. The presented method was used to analyze 81 clinical swine serum specimens. The results obtained by this developed method were compared to those of commercial diagnostic kits. The sensitivity, specificity, and efficiency of the developed method were 92.31, 88.24, and 88.89%, respectively. The excellent characteristics of the yeast@Au microspheres illustrate its great potential for high-throughput immunoassay applications in the fields of disease diagnosis, environmental analysis, and food safety.

Interactions between micro-scale oil droplets in aqueous surfactant solution determined using optical tweezers

HYPOTHESIS

The stability of the emulsions is crucial, which relies on a well-developed understanding of dynamic interaction forces between single dispersed droplets. In the previous studies, many interests focus on the oil droplets of size range of 20-200 µm. However, emulsion droplets with diameter below 10 µm are rarely mentioned, which is the size scale of real emulsion droplets in various applications, such as toners, spacers for liquid crystal displays, and materials in biomedical and biochemical analysis. The micro-scale droplets have many differences on the deformation, internal pressure and hydrodynamic effects. It is necessary to understand the interaction mechanisms between two real size scales of oil droplets for guiding practical production and application.

EXPERIMENTS

In this work, tetradecane was chosen as the model oil phase in all experiments. The interaction forces of two tetradecane droplets with the diameter of 5.0 µm in water in the presence of surfactant and salt solution were directly measured using optical tweezers. The force-distance curves were established, and the zeta potential of tetradecane droplets was studied using Zetasizer Nano ZSP.

FINDINGS

The absolute value of zeta potential of tetradecane droplets was found to decrease with the increase of salt concentration and increase with the increase of surfactant concentration. The repulsive force between two tetradecane droplets was found to decrease with the increase of salt concentration because the electrostatic double-layer force was suppressed gradually with the increase of salt concentration. The "hydrodynamic suction" effect during the process of retraction becomes more pronounced due to the corresponding increase in the hydrodynamic force with the increase of the approaching velocity between the tetradecane droplets. Furthermore, we found the existing model for the measurement of large droplets by atomic force microscope (AFM) is invalid for the measurement of micro-scale droplets by optical tweezers. The deformation of colliding micro-scale droplets can be safely ignored, which is quite different from the large droplets. Our results provide a useful method to study the interaction forces between micro-scale emulsion droplets with pN force resolution, and gives a deep insight of the stabilization mechanism of real size scale of O/W emulsions. These findings have significant implications on the stability of emulsions in many food, cosmetics, medicine, and advanced materials.

Design of polymer particle dispersions (latexes) in the course of radical heterophase polymerization for biomedical applications

Dispersions of polymer particle (DPPs) are increasingly being exploited both as biomolecule carriers, and as markers in various DPP biomedical applications related to cell and molecular biology, enzymology, immunology, diagnostics, in vitro and in vivo visualization, bioseparation, etc. Their potential to reduce reaction scales, lower costs, improve the rate, sensitivity, selectivity, stability and reproducibility of assays governs the diversity of their bioapplications. This review focuses on the design of DPPs with innovative special properties in the course of free radical heterophase polymerization that provides careful control of both macromolecular and colloidal properties. We demonstrate approaches that, according to the polymerization technique, regulate the particle size, shape, particle size distribution, morphology, surface chemistry and functionality, as well as the formation of organic-inorganic hybrid DPPs. The production of bioreagents based on DPPs and their use in bioassay are also reviewed.

Preparation of iron oxide silica particles for Zika viral RNA extraction

In this work, a robust synthetic pathway for magnetic core preparation and silica surface coating of magnetic microparticles is presented. Silica-coated magnetic particles are widely used to extract DNA and RNA from various biological samples. We present a novel route for the synthesis of iron oxide silica particles (Fe₃O₄@Silica) and demonstrate their performance for extracting ZIKA viral RNA from serum. The iron (II, III) oxide (Fe₃O₄), magnetite core is first prepared by ammonia neutralization of ferrous and ferric chloride aqueous solution under argon, followed by the addition of citrate salt to stabilize the surface of the resultant magnetic nanospheres. After this one-pot, two-step synthesis, the magnetic nanospheres are consumed during silica coating by hydrolysis of tetraethoxysilane (TEOS) under alkaline condition. The final product is a sphere-like magnetic aggregate with a size range of 1–2 micron. By simply suspending the magnetic aggregates in guanidinium chloride solution, the silica surface can be prepared for RNA binding. The RNA extraction efficiency was evaluated by extracting ZIKA viral RNA from serum followed by a PCR-based assay. The data indicate excellent recovery of target RNA and removal of PCR inhibitors. This manufacturing procedure for the silica coated microparticles provides a low-cost, effective and ready for scale-up method whose performance is equivalent to commercial alternatives such as magnetic silica surface particles for DNA and RNA sample preparations. The cost of the clinical assays could be largely decreased due to the 100 fold reduction in cost by replacing the commercially available magnetic particles with the developed material for RNA extraction.

Molecular mechanisms for delicately tuning the morphology and properties of Fe3O4 nanoparticle clusters

After being oxidized, dihydric alcohols drive the formation of monodisperse Fe₃O₄ particle clusters.

Self-Stabilized Precipitation Polymerization and Its Application

An effective, value-added use of the large amounts of olefinic compounds produced in the processing of petroleum, aside from ethylene and propylene, has been a long outstanding challenge. Here, we developed a novel heterogeneous polymerization method, beyond emulsion/dispersion/suspension, termed self-stabilized precipitation (2SP) polymerization, which involves the nucleation and growth of nanoparticles (NPs) of a well-defined size without the use of any stabilizers and multifunctional monomers (crosslinker). This technique leads to two revolutionary advances: (1) the generation of functional copolymer particles from single olefinic monomer or complex olefinic mixtures (including C4/C5/C9 fractions) in large quantities, which open a new way to transform huge amount of unused olefinic compounds in C4/C5/C9 fractions into valuable copolymers, and (2) the resultant polymeric NPs possess a self-limiting size and narrow size distribution, therefore being one of the most simple, efficient, and green strategies to produce uniform, size-tunable, and functional polymeric nanoparticles. More importantly, the separation of the NPs from the reaction medium is simple and the supernatant liquid can be reused; hence this new synthetic strategy has great potential for industrial production.

Cell Isolation and Recovery Using Hollow Glass Microspheres Coated with Nanolayered Films for Applications in Resource-Limited Settings

Established cell isolation and purification techniques such as fluorescence-activated cell sorting (FACS), isolation through magnetic micro/nanoparticles, and recovery via microfluidic devices have limited application as disposable technologies appropriate for point-of-care use in remote areas where lab equipment as well as electrical, magnetic, and optical sources are restricted. We report a simple yet effective method for cell isolation and recovery that requires neither specialized lab equipment nor any form of power source. Specifically, self-floating hollow glass microspheres were coated with an enzymatically degradable nanolayered film and conjugated with antibodies to allow both fast capture and release of subpopulations of cells from a cell mixture. Targeted cells were captured by the microspheres and allowed to float to the top of the hosting liquid, thereby isolating targeted cells. To minimize nonspecific adhesion of untargeted cells and to enhance the purity of the isolated cell population, an antifouling polymer brush layer was grafted onto the nanolayered film. Using the EpCAM-expressing cancer cell line PC-3 in blood as a model system, we have demonstrated the isolation and recovery of cancer cells without compromising cell viability or proliferative potential. The whole process takes less than 1 h. To support the rational extension of this platform technology, we introduce extensive characterization of the critical design parameters: film formation and degradation, grafting with a poly(ethylene glycol) (PEG) sheath, and introducing functional antibodies. Our approach is expected to overcome practical hurdles and provide viable targeted cells for downstream analyses in resource-limited settings.

Synthesis and Characterization of Polystyrene Core/Polyacrolein Shell Latexes

The poly(styrene/acrolein) latexes were synthesized in an emul sifier-free emulsion-precipitation polymerization. Monodisperse particles from 0.30 μm to 0.52 μm, depending on the acrolein monomer feed, were obtained. More acrolein in the monomer feed yielded latex particles with smaller di ameters. Analyses indicate that the particles have a core-shell morphology. The core is rich in the hydrophobic (polystyrene) component whereas the shell is composed mainly of hydrophilic polyacrolein. Significant changes in polyacro lein in the latexes (from 0.03 to 0.28) has less influence on the composition of the shell (from 0.5 to 0.84, respectively). The surface of the latex particles is smooth and can be penetrated by 2,4-dinitrophenyl hydrazine to the depth from 1.5 to 3.5 Å. These poly(styrene/acrolein) latexes are capable of binding ca. 3 mg of human globulins or ca. 1 mg of human serum albumin on 1 m2 of the latex surface.

Synthesis of Monodispersed Submillimeter-Sized Molecularly Imprinted Particles Selective for Human Serum Albumin Using Inverse Suspension Polymerization in Water-in-Oil Emulsion Prepared Using Microfluidics

We synthesized monodispersed submillimeter-sized (100 μm-1 mm) microgels by inverse suspension polymerization of water-soluble monomer species with a photoinitiator in water-in-oil (W/O) droplets formed by the microchannel. After fundamental investigations of the selection of suitable surfactants, surfactant concentration, and flow rate, we successfully prepared monodispersed submillimeter-sized W/O droplets. Because radical polymerization based on thermal initiation was not appropriated based on colloidal stability, we selected photoinitiation, which resulted in the successful synthesis of monodispersed submillimeter-sized microgels with sufficient colloidal stability. The microgel size was controlled by the flow rate of the oil phase, which maintained the monodispersity. In addition, the submillimeter-sized microgels exhibit high affinity and selective binding toward HSA utilizing molecular imprinting. We believe the monodispersed submillimeter-sized molecularly imprinted microgels can be used as affinity column packing materials without any biomolecules, such as antibodies, for sample pretreatment to remove unwanted proteins without a pump system.

Fundamentals and application of magnetic particles in cell isolation and enrichment: a review

Magnetic sorting using magnetic beads has become a routine methodology for the separation of key cell populations from biological suspensions. Due to the inherent ability of magnets to provide forces at a distance, magnetic cell manipulation is now a standardized process step in numerous processes in tissue engineering, medicine, and in fundamental biological research. Herein we review the current status of magnetic particles to enable isolation and separation of cells, with a strong focus on the fundamental governing physical phenomena, properties and syntheses of magnetic particles and on current applications of magnet-based cell separation in laboratory and clinical settings. We highlight the contribution of cell separation to biomedical research and medicine and detail modern cell-separation methods (both magnetic and non-magnetic). In addition to a review of the current state-of-the-art in magnet-based cell sorting, we discuss current challenges and available opportunities for further research, development and commercialization of magnetic particle-based cell-separation systems.

Calf thymus histone-conjugated magnetic poly(2-oxoethyl methacrylate) microspheres for affinity isolation of anti-histone IgGs from the blood serum of patients with systemic lupus erythematosus

Affinity isolation of anti-histone immunoglobulins from blood serum of systemic lupus erythematosus patients using histone-conjugated magnetic poly(2-oxoethyl methacrylate) microspheres (IO-iron oxide, HIS-histone).

Macrocyclic receptors immobilized to monodisperse porous polymer particles by chemical grafting and physical impregnation for strontium capture: a comparative study

Separation of strontium is of great significance for radioactive waste treatment and environmental remediation after nuclear accidents. In this work, a novel class of adsorbent (Crown-g-MPPPs) was synthesized by chemical grafting a macrocyclic ether receptor to monodisperse porous polymer particles (MPPPs) for strontium adsorption. Meanwhile, a counterpart material (Crown@MPPPs) with the receptor molecules immobilized to the MPPPs substrate by physical impregnation was prepared. To investigate how the immobilization manner and distribution of the receptors influence the adsorption ability, a comparative study on the adsorption behaviour of the two materials towards Sr(II) in HNO3 media was accomplished. Due to the shorter diffusion path and covalently-bonded structure, Crown-g-MPPPs showed faster adsorption kinetics and better stability for cycle use. While Crown@MPPPs had the advantages of facile synthesis and higher adsorption capacity, owing to the absence of conformational constraint to form complexation with Sr(II). Kinetic functions (Lagergren pseudo-first-order/pseudo-second-order functions) and adsorption isotherm models (Langmuir/Freundlich models) were used to fit the experimental data and examine the adsorption mechanism. On this basis, a chromatographic process was proposed by using Crown@MPPPs for an effective separation of Sr(II) (91%) in simulated high level liquid waste (HLLW).

Polystyrene Microbeads by Dispersion Polymerization: Effect of Solvent on Particle Morphology

Polystyrene microspheres (PS) were synthesized by dispersion polymerization in ethanol/2-Methoxyethanol (EtOH/EGME) blend solvent using styrene (St) as monomer, azobisisobutyronitrile (AIBN) as initiator, and PVP (polyvinylpyrrolidone) K-30 as stabilizer. The typical recipe of dispersion polymerization is as follows: St/Solvent/AIBN/PVP = 10 g/88 g/0.1 g/2 g. The morphology of polystyrene microspheres was characterized by the scanning electron microscopy (SEM) and the molecular weights of PS particles were measured by the Ubbelohde viscometer method. The effect of ethanol content in the blend solvent on the morphology and molecular weight of polystyrene was studied. We found that the size of polystyrene microspheres increased and the molecular weight of polystyrene microspheres decreased with the decreasing of the ethanol content in the blend solvent from 100 wt% to 0 wt%. What is more, the size monodispersity of polystyrene microspheres was quite good when the pure ethanol or pure 2-Methoxyethanol was used; however when the blend ethanol/2-Methoxyethanol solvent was used, the polystyrene microspheres became polydisperse. We further found that the monodispersity of polystyrene microspheres can be significantly improved by adding a small amount of water into the blend solvent; the particles became monodisperse when the content of water in the blend solvent was up to 2 wt%.

Synthesis of monodisperse nanocolloidal microspheres with controlled size by vesicle bilayer templating

Uniform PS colloidal particles with controllable size ranging from 60 to 150 nm were prepared on a mass scale by using the bilayers of hyperbranched polymer vesicles as templates.