Functional Microspheres Research Articles

Removal of uranium and fluorine from wastewater by double-functional microsphere adsorbent of SA/CMC loaded with calcium and aluminum

A novel dual functional microsphere adsorbent of alginate/carboxymethyl cellulose sodium composite loaded with calcium and aluminum (SA/CMC-Ca-Al) is prepared by an injection device to remove fluoride and uranium, respectively, from fluoro-uranium mixed aqueous solution. Batch experiments are performed at different conditions: pH, temperature, initial concentration and contact time. The results show that the maximum adsorption amount for fluoride is 35.98mg/g at pH 2.0, 298.15K concentration 100mg/L, while that for uranium is 101.76mg/g at pH 4.0, 298.15K concentration 100mg/L. Both of the adsorption process could be well described by Langmuir model. The adsorption kinetic data is fitted well with pseudo-first-order model for uranium and pseudo-second-order model for fluoride. Thermodynamic parameters are also evaluated, indicating that the adsorption of uranium on SA/CMC-Ca-Al is a spontaneous and exothermic process, while the removal of fluoride is non-spontaneous and endothermic process. The mechanism of modification and adsorption process on SA/CMC-Ca-Al is characterized by FT-IR, SEM, EDX and XPS. The results show that Ca (II) and Al (III) are loaded on SA/CMC through ion-exchange of sodium of SA/CMC. The coordination reaction and ion-exchange happen during the adsorption process between SA/CMC-Ca-Al and uranium, fluoride. Results suggest that the SA/CMC-Ca-Al adsorbent has a great potential in removing uranium and fluoride from aqueous solution.

Encapsulating quantum dots with amino functionalized mesoporous hollow silica microspheres for the sensitive analysis of formaldehyde in seafood

We developed a hybrid fluorescent material using amino functional mesoporous hollow silica microspheres (MHSM) encapsulated with CdTe quantum dots (QDs).

Shaping of Alginate–Silica Hybrid Materials into Microspheres through Vibrating-Nozzle Technology and Their Use for the Recovery of Neodymium from Aqueous Solutions

The vibrating-nozzle technology is very interesting to very easily and very rapidly produce industrial amounts of functional microspheres. The technology was used to make hybrid alginate–silica microspheres by droplet coagulation. The microspheres were formed starting from suspensions of sodium alginate, and coagulation occurred in an aqueous solution of calcium ions. To enhance the mechanical properties of the alginate raw material, it was combined with two different silica sources: tetramethyl orthosilicate (TMOS) and commercial silica powder. The two different batches of alginate–silica microspheres were fully compared with regard to their morphology, composition, shrinking behavior, and stability in acidic conditions. It was shown that the incorporation of an inorganic matrix resulted in a material with a better stabilized porous structure and a higher resistance in an acidic environment. Both are important when functional particles are designed to be used for adsorption of metal ions, either as a sti...

Functional porous carboxymethylcellulose microspheres – preparation and reduction of hydrogen cyanide yield in cigarette smoke

To selectively reduce the yield of hydrogen cyanide in cigarette smoke, porous carboxymethylcellulose microspheres were prepared through the sol–gel method. Cupric ions, the functional groups that have high complexing ability to hydrogen cyanide, were introduced to the carboxymethylcellulose microspheres during the sol–gel process. The microspheres were characterised using nitrogen adsorption and scanning electron microscopy. The microspheres have a predominantly macroporous structure indicating weak physisorption properties, but sufficient functional cupric ions groups to selectively adsorb hydrogen cyanide. With these carboxymethylcellulose microspheres as filter additives, the smoke yield of hydrogen cyanide could be reduced by up to 42%, indicating great potential of these microspheres as absorbents for removing hydrogen cyanide from cigarette smoke.

Preparation and Application of Functional Inorganic/Polymer Hollow Microspheres Via Double In Situ Mini-Emulsion Polymerization

Silica/polymer hollow microspheres were prepared via double in situ mini-emulsion polymerization by taking advantage of phase separation between the growing polymer and inorganic TEOS phase. Then hybrid hollow microspheres were surface modified by the addition of GMA during the process of polymerization. The obtained surface–functional hybrid hollow microspheres were applied as a filler in polysulfide sealant system. The inorganic/polymer hollow microspheres were characterized by Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), thermogravimetric/derivative thermal gravimetric analysis (TGA/DTG), and thixotropic experiment, respectively. The results showed that the as-prepared inorganic/polymer microspheres had a hollow structure and the size was in the range of 200–600 nm. The thixotropy and heat resistance properties of polysulfide sealant were improved after the addition of hybrid hollow microspheres.

On-demand one-step synthesis of monodisperse functional polymeric microspheres with droplet microfluidics.

A simple and robust method for one-step synthesis of monodisperse functional polymeric microspheres was established by generation of reversed microemulsion droplets in aqueous phase inside microfluidic chips and controlled evaporation of the organic solvent. Using this method, water-soluble nanomaterials can be easily encapsulated into biodegradable Poly(D,L-lactic-co-glycolic acid) (PLGA) to form functional microspheres. By controlling the flow rate of microemulsion phase, PLGA polymeric microspheres with narrow size distribution and diameters in the range of ∼50-100 μm were obtained. As a demonstration of the versatility of the approach, high-quality fluorescent CdTe:Zn(2+) quantum dots (QDs) of various emission spectra, superparamagnetic Fe3O4 nanoparticles, and water-soluble carbon nanotubes (CNTs) were used to synthesize fluorescent PLGA@QDs, magnetic PLGA@Fe3O4, and PLGA@CNTs polymeric microspheres, respectively. In order to show specific applications, the PLGA@Fe3O4 were modified with polydopamine (PDA), and then the silver nanoparticles grew on the surfaces of the PLGA@Fe3O4@PDA polymeric microspheres by reducting the Ag(+) to Ag(0). The as-prepared PLGA@Fe3O4@PDA-Ag microspheres showed a highly efficient catalytic reduction of the 4-nitrophenol, a highly toxic substance. The monodisperse uniform functional PLGA polymeric microspheres can potentially be critically important for multiple biomedical applications.

Raspberrylike SiO2@reduced graphene oxide@AgNP composite microspheres with high aqueous dispersity and excellent catalytic activity.

The hybridizations of functional microspheres with graphene or graphene oxide (GO) sheets often suffer from severe agglomeration behaviors, leading to poor water dispersity of the resultant composite materials. Here, we first demonstrate that the sonication-assisted self-assembly of tiny GO sheets (whose lateral size less than 200 nm) on microspheric substrates like cationic polyelectrolyte-modified SiO2 microspheres could effectively overcome such a common drawback. On the basis of this facile strategy, we further developed reduced graphene oxide/silver nanoparticle composite film wrapped SiO2 microspheres, which not only possessed unique raspberrylike structure and high aqueous dispersity but also exhibited exceptional catalytic activity toward the reduction of 4-nitrophenol.

Different dispersion polymerization strategies influence the quality of fluorescent poly (St‐co‐GMA) microspheres

ABSTRACTThe polymerization strategy plays a vital role in the preparation of functional microspheres. In this work, fluorescent poly (styrene‐co‐glycidyl methacrylate) (PSt‐GMA) microspheres were synthesized via one‐stage and two‐stage dispersion polymerization with 4‐Bis(5‐phenyl‐1,3‐oxazol‐2‐yl)benzene (POPOP) as fluorescence agent. SEM and DLS were adopted to characterize the properties of prepared microspheres. The UV‐vis and fluorescence spectroscopy were used to analyze the mechanisms of two‐stage dispersion polymerization. The experimental results showed that the size distribution and fluorescence intensity of prepared microspheres could be improved by two‐stage dispersion polymerization compared to one‐stage dispersion polymerization. In addition, according to UV‐vis, the interactions between POPOP and Poly (N‐vinyl pyrrolidone) (PVP) as well as POPOP and Glycidyl methacrylate (GMA) could affect the particle size and its distribution. UV‐vis and fluorescence spectra implied that the POPOP existed outside of the particle's core via two‐stage strategy. The monomer conversion of styrene was similar at the beginning of reaction; however, the monomer conversion of styrene by two‐stage strategy was higher than that of by one‐stage strategy. In a word, two‐stage dispersion polymerization could prepare fluorescent microspheres with the monodispersion micrometer‐size and high quality. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41927.

Preparation and Characterization of Platinum and Rhodium Nanoparticles Stabilized by Functional Polymer Microspheres

Preparation and Characterization of Platinum and Rhodium Nanoparticles Stabilized by Functional Polymer Microspheres

Enantioselective absorption of enantiomers with maleic anhydride-β-cyclodextrin modified magnetic microspheres

Multifunctional magnetic microspheres have enormous potential in diverse fields. In this work, surface chiral-modified magnetic microspheres as chiral selectors, are prepared by polymerizing maleic anhydride-β-cyclodextrin (MAH-β-CD) for the enantioselective absorption of four enantiomers. The successful grafting of MAH-β-CD onto the surface of magnetic microspheres is confirmed by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. The prepared functional microspheres have a three-ply structure with an average particle size of 550 nm and a high saturation magnetization of 60 emu g−1. The amount of MAH-β-CD modified on the P(MBAAm)@Fe3O4 was about 149.1 mg g−1. The analysis results of specific rotation and capillary electrophoresis reveal that the MAH-β-CD-modified Fe3O4 microspheres show stronger complexation of (−)-enantiomers than (+)-enantiomers. In addition, the MAH-β-CD-modified Fe3O4 microspheres have stronger enantioselective absorption for double-ring chiral compounds. These chiral-functionalized magnetic microspheres are therefore expected to be an efficient and economical chiral separation method for use in further research.

Synthesis of PMMA Microparticles with a Narrow Size Distribution by Photoinitiated RAFT Dispersion Polymerization with a Macromonomer as the Stabilizer

Macromonomers can serve as efficient and effective stabilizers for dispersion polymerization of monomers such as styrene and methyl methacrylate, but the size distributions of the polymer microparticles obtained tend to be broad. We are interested in functional microbeads which can be used for immunoassays, where the size distribution has to be very narrow. We report a photoinitiated RAFT dispersion polymerization of methyl methacrylate (MMA) in ethanol–water mixtures, with methoxy-poly(ethylene glycol) methacrylate (Mn = 2000 g/mol, EO45) as the reactive steric stabilizer. We identify reaction conditions where one can obtain PMMA microspheres with coefficient of variation in the particle diameter (CVd) less than 3%. Carboxy-functional PMMA microspheres were obtained by a two-stage (seeded) polymerization with methacrylic acid (MAA) added as a comonomer in the second stage. We show that the functional microspheres prepared in this way are effective substrates for the covalent attachment of proteins such as BSA and IgG immunoglobulins. In one set of experiments with a dye-labeled secondary antibody, we found that we could detect 104 IgGs per PMMA microbead.

Folic acid-conjugated pH/temperature/redox multi-stimuli responsive polymer microspheres for delivery of anti-cancer drug

The folic acid (FA)-conjugated pH/temperature/redox multi-stimuli responsive poly(methacrylic acid-co-N,N-bis(acryloyl)cystamine/poly(N-isopropylacrylamide-co-glycidyl methacrylate-co-N,N-bis(acryloyl)cystamine) microspheres were prepared by a two-stage distillation–precipitation polymerization with subsequent surface modification with FA. The microspheres were characterized by transmission electron microscopy, dynamical light scattering, Fourier-transform infrared spectra, UV–vis spectra and elemental analysis. The degradation of the functional microspheres could be triggered by a reductive reagent, such as glutathione, due to presence of BAC crosslinker. The drug-loaded microspheres exhibited a pH/temperature/redox multi-stimuli responsive drug release character for doxorubicin hydrochloride as a model anti-cancer drug, which was efficiently loaded into the microspheres with a high loading capacity of 208.0% and an encapsulation efficiency of 85.4%. In vitro drug delivery study indicated that the FA-conjugated microspheres could deliver Dox into MCF-7 cells more efficiently than the microspheres without functionalization of FA. Furthermore, WST-1 assay showed that the microspheres had no obvious toxicity to MCF-7 cells even at a high concentration of 2000μgmL−1. The resultant microsphere may be a promising vector for delivery of anti-cancer drugs as it exhibits a low cytotoxicity and degradability, precise molecular targeting property and multi-stimuli responsively controlled drug release.

Inverse Opal Spheres Based on Polyionic Liquids as Functional Microspheres with Tunable Optical Properties and Molecular Recognition Capabilities

Based on the combination of the unique features of both polyionic liquids and spherical colloidal crystals, a new class of inverse opaline spheres with a series of distinct properties was fabricated. It was found that such photonic spheres could not only be used as stimuli-responsive photonic microgels, but also serve as multifunctional microspheres that mimic the main characteristics of conventional molecules, including intrinsic optical properties, specific molecular recognition, reactivity and derivatization, and anisotropy.

Monodisperse functional microspheres from step-growth “click” polymerizations: preparation, functionalization and implementation

We introduce a new paradigm in microparticles, where “click” chemistry enables the fabrication of functional monodisperse microspheres from step-growth polymerization at ambient conditions.

Engineering PLGA doped PCL microspheres with a layered architecture and an island–sea topography

Composite polymer devices have gained considerable interest in biomedical applications. In this work, a composite poly(lactic-co-glycolic acid)/poly(e-caprolactone) (PLGA/PCL) microsphere with a layered architecture and an island–sea topography was developed. PCL was found to occupy the shell layer of the microsphere, while PLGA constituted surface islands and the internal core. This subtle structure was derived from the different external and internal rates of phase separation between PCL and PLGA. The existence of the PLGA islands enhanced the hydrophilicity of the PCL shell. Mouse mesenchymal stem cells (mMSCs) were cultured and they grew well on the PLGA/PCL microspheres. The surface of the microsphere was microscopically composed of PCL sea and PLGA islands, and the mMSCs showed a trend to attach to the more hydrophilic PLGA islands and bridged between adjacent microspheres. This paper provides a new alternative to design functional microspheres for potential application in tissue repair.

Synthesis of Highly Monodisperse Surface-Functional Microspheres by Photoinitiated RAFT Dispersion Polymerization Using Macro-RAFT Agents

Highly monodisperse PMMA microspheres have been synthesized by photoinitiated RAFT dispersion polymerization in the presence of a Macro-RAFT agent and a small molecular RAFT agent. A particle yield of over 90% was achieved within 3 h under UV irradiation at room temperature. The Macro-RAFT agent acts as a stabilizer and stabilizes the particles via formation of block copolymers in situ, and XPS analysis shows that about 29.9% of the particle surface was covered by the stabilizer. Various surface functional microspheres were prepared by using four kinds of Macro-RAFT agents, including poly(methoxy poly(ethylene glycol) acrylate)-based trithiocarbonate (P(mPEGA)-TTC), poly(methoxy poly(ethylene glycol) acrylate-co-acrylic acid)-based trithiocarbonate (P(mPEGA-co-AA)-TTC), poly(acrylic acid)-based trithiocarbonate (PAA-TTC), and poly(methoxy poly(ethylene glycol) acrylate-co-4-vinylpyridine)-based trithiocarbonate (P(mPEGA-co-4VP)-TTC). Ag/PMMA nanocomposite spheres were prepared using the P(mPEGA-co-AA)-TTC...

Synthesis of Poly[Cyclotriphosphazene-Co-(4, 4'-Sulfonyldiphenol)] Microspheres Grafted by Water-Soluble Chitosan

Poly [cyclotriphosphazene-co-(4, 4-sulfonyldiphenol)] microspheres grafted by water-soluble chitosan (PZSMS-g-Cs) were successfully prepared via a facile strategy. The water-soluble chitosan, which has low polymerization degree and narrow molecular weight distribution, was prepared by degradation from common macromolecular chitosan. The morphology and structure of PZSMS-g-Cs were characterized by SEM and TEM. The successful fabrication of PZSMS-g-Cs was confirmed by FTIR. The product PZSMS-g-Cs was found to have good water soluble property. The paper presents a simple, economic and efficient route to preparing functional hybrid inorganic-organic microspheres with good water soluble property.

Fabrication of distilled water-soluble chitosan/alginate functional multilayer composite microspheres

Polysaccharides-based functional microspheres were fabricated under mild conditions. Firstly, magnetic alginate microspheres were prepared by emulsification/internal gelation and acted as substrates. Then the multilayer composite microspheres (MCM) were obtained through the layer-by-layer assembly of the distilled water-soluble chitosan and alginate. The components, morphology, and size distribution of the microspheres were characterized by element analysis (EA), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and laser particle size analyzer (LPSA). Both EA and XPS analysis results indicated that alternate immersion was an effective method for preparing MCM. Vibrating sample magnetometer, SEM and LPSA results showed that the microspheres had good dispersion, uniform particle size and were superparamagnetic. In addition, in vitro drug release behaviors of the microspheres were investigated by using hemoglobin (HB) and Coomassie brilliant blue G250 (CBB) as model drugs. It was found that the release rates of both HB and CBB from the composite microspheres were slower than those from the substrates.

A new type of cation‐exchange polymeric microspheres with pendant methylenethiol groups

Synthesis and characterization of the new styrene microspheres with pendant methylenethiol groups are presented. At the first stage, the polymeric matrices were obtained by the suspension–emulsion polymerization of monomers: styrene (St) with 2,3‐(2‐hydroxy‐3‐methacryloyloxypropoxy)naphthalene (NAF.DM) or (bis[4(2‐hydroxy‐3‐methacryloyloxypropoxy)phenyl]sulfide (BES.DM) or divinylbenzene (DVB). At the second stage, the modification of the sythesized matrices was performed as follows: the matrices were reacted with paraformaldehyde in the presence of hydrochloric acid forming chloromethyl derivatives. Next, by reaction with thiourea, a thiouronium salt was obtained, and then the hydrolysis with NaOH solution and acidification with HCl were carried out. Finally, microspheres with –CH2SH groups on their surface were obtained. The –SH group content (elemental analysis), thermal properties (thermogravimetric analysis), Fourier transform infrared as well as the swelling characteristics of the functional microspheres were examined. The surface texture was also visualized by the atomic force microscopy (AFM) method. The obtained polymers were screened towards sorption of Cu(II) ions. It was found that a better correlation between the experimental Cu(II) uptake and the theoretical curves predicted by the Langmuir or Freundlich models is obtained in the case of the DVB–St–SH polymer. In the case of the BES.DM–St–SH and 2,3‐NAF–St–SH ones, the Freundlich model corresponded quite well to the experimental data. Copyright © 2013 John Wiley & Sons, Ltd.

Rapid Synthesis of Functional Carbon Microspheres: Preparation, Forming Mechanism and Application in Formic Acid and Ammonia Treatment

Rapid Synthesis of Functional Carbon Microspheres: Preparation, Forming Mechanism and Application in Formic Acid and Ammonia Treatment