Functional Polymeric Microspheres Research Articles

Amine‐Functionalized Polyglycidyl Methacrylate Microsphere as a Unified Template for the Synthesis of Gold Nanoparticles and Single‐Crystal Gold Plates

Polyglycidyl methacrylate (PGMA) microspheres, crosslinked and surface-functionalized by amine, can be used as a solid-state template for the synthesis of gold (Au) crystals in the forms of either nanoparticles (NPs) or plates. It is discovered that the polymer microsphere acts as an internal template to cultivate Au NPs inside the microsphere or an external template to generate the single-crystal plates depending on the critical concentration (Ccr ) of gold ions. The ion-dipole interaction and the structure-dependent solubility of gold induce two distinct gold nanostructures in the presence of the functionalized polymer microspheres. The catalytic activity and long-term storage of the developed gold nanostructures that can be easily scaled-up for mass production through the developed novel methodology is demonstrated.

Photoinitiated RAFT Dispersion Polymerization: A Straightforward Approach toward Highly Monodisperse Functional Microspheres

A straightforward dispersion polymerization procedure for the synthesis of monodisperse functional polymeric microspheres is proposed in this article. This method overcomes the problems deriving from the highly sensitive nucleation stage by introducing both photoinitiation and a RAFT chain transfer agent to the reaction. The process of the formation and growth of particles in the procedure was investigated and found to be quite different from that in a traditional dispersion polymerization. Various kinds of PMMA-based functional microspheres with high size uniformity were synthesized in a single step by this strategy. The microspheres remained uniform in size, even at concentrations of cross-linker or functional comonomer up to 10 wt %.

A Facile Route to Boronic Acid Functional Polymeric Microspheres via Epoxide Ring Opening

Boronic acid-functionalized microspheres are prepared for the first time via mild epoxide ring opening based on porous cross-linked polymeric microspheres (diameter ≈ 10 μm, porosity ≈ 1000 Å). Quantitative chemical analysis by XPS and EA evidences that there is a greater functionalization with boronic acid when employing a sequential synthetic method [1.7 atom% boron (XPS); 1.12 wt% nitrogen (EA)] versus a one-pot synthetic method [0.2 atom% boron (XPS); 0.60 wt% nitrogen (EA)] yielding grafting densities ranging from approximately 2.5 molecules of boronic acid per nm(2) to 1 molecule of boronic acid per nm(2), respectively. Furthermore, the boronic acid-functionalized microspheres are conjugated with a novel fluorescent glucose molecule demonstrating a homogeneous spatial distribution of boronic acid.

Immobilisation and characterisation of biocatalytic co-factor recycling enzymes, glucose dehydrogenase and NADH oxidase, on aldehyde functional ReSyn™ polymer microspheres

The use of enzymes in industrial applications is limited by their instability, cost and difficulty in their recovery and re-use. Immobilisation is a technique which has been shown to alleviate these limitations in biocatalysis. Here we describe the immobilisation of two biocatalytically relevant co-factor recycling enzymes, glucose dehydrogenase (GDH) and NADH oxidase (NOD) on aldehyde functional ReSyn™ polymer microspheres with varying functional group densities. The successful immobilisation of the enzymes on this new high capacity microsphere technology resulted in the maintenance of activity of ∼40% for GDH and a maximum of 15.4% for NOD. The microsphere variant with highest functional group density of ∼3500μmolg−1 displayed the highest specific activity for the immobilisation of both enzymes at 33.22Umg−1 and 6.75Umg−1 for GDH and NOD with respective loading capacities of 51% (0.51mgmg−1) and 129% (1.29mgmg−1). The immobilised GDH further displayed improved activity in the acidic pH range. Both enzymes displayed improved pH and thermal stability with the most pronounced thermal stability for GDH displayed on ReSyn™ A during temperature incubation at 65°C with a 13.59 fold increase, and NOD with a 2.25-fold improvement at 45°C on the same microsphere variant. An important finding is the suitability of the microspheres for stabilisation of the multimeric protein GDH.

A supramolecular route towards core–shell polymeric microspheres in water via cucurbit[8]uril complexation

Core-shell polymeric microspheres with a cleavable shell were prepared in water using cucurbit[8]uril to bring together functional polymeric microspheres and functional polymers. This supramolecular approach was employed to switch the cytotoxicity of the polymeric microspheres, leading to potential applications in the eradication of cancer cells.

Ambient temperature synthesis of narrow or monodisperse, highly cross-linked, and “living” polymer microspheres by atom transfer radical precipitation polymerization

A facile ambient temperature atom transfer radical precipitation polymerization (ATRPP) approach is developed for the efficient one-pot synthesis of narrow or monodisperse, highly cross-linked, and “living” polymer microspheres under mild reaction conditions. The simple introduction of an atom transfer radical polymerization (ATRP) mechanism into a precipitation polymerization system, together with the rational use of polar alcoholic solvents, allows the direct ambient temperature preparation of uniform “living” polymer microspheres with their number-average diameters ranging from 0.36–1.95 μm and their particle size distributions being typically less than 1.01. The polymerization parameters (including the monomer loading, polymerization time, and kind of alcoholic solvent) proved to have a pronounced influence on the yields and morphologies of the polymer microspheres, which makes it very convenient to tailor the particle sizes by tuning the polymerization conditions. The general applicability of ambient temperature ATRPP was demonstrated by its successful application in a range of alcoholic solvents as well as its versatility in the synthesis of a series of uniform copolymer microspheres of different monovinyl functional monomers (4-vinylpyridine, glycidyl methacrylate, methyl methacrylate, and 2-hydroxyethyl methacrylate) with ethylene glycol dimethacrylate. In addition, the “livingness” of the resulting polymer microspheres was confirmed by their direct grafting of hydrophilic polymer brushes via surface-initiated ambient temperature ATRP, leading to advanced functional polymer microspheres with significantly improved surface hydrophilicity.

Synthesis of polymer microspheres functionalized with chiral ligand by precipitation polymerization and their application to asymmetric transfer hydrogenation

Monodisperse, crosslinked poly(divinylbenzene) and poly(methacrylic acid-co-ethylene glycol dimethacrylate) microspheres with (1R,2R)-N1-toluenesulfonyl-1,2-diphenylethylene-1,2-diamine ((R,R)-TsDPEN) moiety were successfully prepared by precipitation polymerization. Introduction site of the (R,R)-TsDPEN moiety into the polymer microspheres could be controlled by changing the order of addition of the corresponding monomers. The functionalized polymer microspheres were applied to asymmetric transfer hydrogenation of ketone and imine. Polymer microsphere-supported chiral catalysts showed good reactivity and enantioselectivity in the catalytic asymmetric transfer hydrogenations. Chiral secondary alcohol was quantitatively obtained with 94% ee in the asymmetric transfer hydrogenation of acetophenone in water. We also found that introduction site of the chiral catalyst and hydrophobicity of the microspheres, as well as degree of the crosslinking, affected the yield and enantioselectivity of chiral product in this reaction. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3340–3349, 2010

Synthesis of Microspheres as Versatile Functional Scaffolds for Materials Science Applications

Functional polymeric microspheres are of great interest as they have high potential as functional scaffolds in material science applications. Highly cross-linked poly(divinyl benzene) (pDVB) microspheres can be synthesized via the precipitation polymerization technique. Recently, various methods of controlled polymerization techniques (e.g., atom transfer radical polymerization (ATRP), reversible addition fragmentation chain transfer (RAFT), and anionic ring-opening polymerization (AROP)) and highly orthogonal conjugation methods (e.g., copper-catalyzed Huisgen 1,3-dipolar cycloaddition of azides and terminal alkynes (CuAAc), thiol-ene addition and RAFT hetero Diels-Alder cycloaddition (RAFT-HDA)) have been applied to functionalize microspheres via the “grafting from” and “grafting to” approaches. The synthesis of pDVB microspheres, their susbsequent modification via grafting of polymer strands to the surface, and the characterization of the obtained functional particles are reviewed.

ADSORPTION OF DINITROBENZOATE-MODIFIED HEMA/NVP MICROSPHERE FOR CREATININE AND THE MECHANISM OF CHEMISORPTION

制备了平均粒径为180μm的甲基丙烯酸β-羟乙酯（HEMA）与N-乙烯基吡咯烷酮（NVP）交联共聚物微球（HEMA/NVP）,使用3,5-二硝基苯甲酰氯（DNBC）对其进行了化学改性,制得了表面键合有大量3,5-二硝基苯甲酸酯基（DNBZ）的功能微球DNBZ-HEMA/NVP;采用红外光谱（FTIR）与化学分析法对其化学结构及组成进行了表征;重点研究了功能微球DNBZ-HEMA/NVP对肌酐的吸附特性与吸附机理.静态吸附实验表明,DNBZ-HEMA/NVP对肌酐具有强的吸附作用,交联微球HEMA/NVP经DNBC化学改性后,对肌酐的吸附容量提高了20倍;DNBZ-HEMA/NVP对肌酐的吸附性能受介质pH值及盐度的影响很大;当pH值较小或较大时,吸附容量都较低,pH=8.5时,吸附容量最大;介质的盐度越大,吸附容量越小.研究结果表明,DNBZ-HEMA/NVP对肌酐的吸附属化学吸附,而且是静电相互作用驱动下的化学吸附.

Preparation of silica/polymer hybrid microspheres and the corresponding hollow polymer microspheres with functional groups

AbstractMonodisperse functional silica/polymer core–shell hybrid microspheres were prepared by a two‐stage reaction with silica grafting of 3‐(methacryloxy)propyl trimethoxysiliane (MPS) as core and polymer as shell having various functional groups such as chloromethyl, pyridyl, carboxylic acid, hydroxyl, and ester. MPS‐modified silica core was synthesized by the Stöber method and subsequently grafted with MPS as the first‐stage reaction. The functional polymer shell was then encapsulated over the MPS‐modified silica by distillation precipitation copolymerization of divinylbenzene (DVB) as a crosslinker and comonomers with different functional groups, including chloromethylstyrene (CMSt), vinyl pyridine (VPy), methacrylic acid (MAA), 2‐hydroxyethylmethacrylate (HEMA), ethyl methacrylate (EMA), ethyleneglycol dimethacrylate (EGDMA), and trimethylol propanetrimethacrylate (Trim), in neat acetonitrile with 2,2′‐azobisisobutyronitrile (AIBN) as an initiator. The encapsulation of the functional polymer shell onto the MPS‐modified silica core particles was driven by the capture of oligomer radicals the vinyl groups on the surface of the MPS‐modified silica cores during the second‐stage distillation precipitation copolymerization in the absence of any stabilizer or surfactant. The functionality and the shell thickness of the inorganic/polymer core–shell hybrid particles were controlled by the amount of DVB crosslinker and the functional comonomers during the copolymerization. The corresponding hollow polymer microspheres with various functional groups, including chloromethyl, pyridyl, carboxylic acid, and ester groups were further developed after the selective removal of silica core with hydrofluoric acid. The functional core–shell silica/polymer hybrid microspheres and the corresponding functional hollow polymer microspheres were characterized with transmission electron microscopy (TEM) and Fourier transform infrared spectra (FT‐IR). Copyright © 2008 John Wiley & Sons, Ltd.

An Optical Chemical Sensor Based on Swellable Dicarboxylate Functionalized Polymer Microspheres for pH Copper and Calcium Determination

An optical chemical sensor based on polymer swelling and shrinking has been studied by way of optical transmission. Polyvinylbenzyl chloride cross-linked with divinylbenzene and derivatized as the dicarboxylate was dispersed as microspheres in a hydrogel membrane. The absorbance was measured vs. the wavelength upon exposing the modified membrane to solutions of varying pH (3.0–9.0). At low pH (3.0), the absorbance had the highest value (1.34), while the absorbance decreased significantly (1.10) when the pH was increased to 9.0, indicating polymer swelling. The modified membrane was also used for sensing metal ions, in particular calcium and copper. Complex formation with the dicarboxylate functionality caused the polymer to shrink. This resulted in an increase in absorbance for a concentration ranging from 1.0×10−3 to 4.0×10−3 M.

Functional polymeric microspheres synthesized by radiation polymerization

New functional microspheres consisting of diethylene glycol dimethacrylate (2G) and a methacryloyl monomer containing four amino acids, l-asparagynyl- l-alanyl- l-asparagynyl l-proline methyl ester (MA-NANPOMe) were synthesized by radiation induced co-polymerization. These four amino acids were previously identified as a part of the immunodominant region of the circumsporozoite (CS) protein of Plasmodium falciparum. The use of this synthetic peptide as an antigen in immunoassay for malaria is promising: the microspheres exposed to the sera of malaria patients showed marked fluorescence, while the spheres contacted with sera of healthy donors showed no fluorescence.

Preparation of Functional Polymer Microspheres by Dispersion Polymerization.

Monodispersed polymer spheres having irregular surface were prepared using monodispersed polystyrene spheres of 10μm diameter as nucleus. They were then patched with n-butyl methacrylate polymer particles by dispersion polymerization of n-butyl methacrylate.The surface condition of the monodispersed polymer spheres was controlled by controlling the mixing rate during the dispersion polymerization.More uniformly patched and more minute polymer particles were recognized on the surface of each sphere at higher mixing rates.

Properties of functional polymeric microspheres obtained by radiation polymerization of acrolein

Radiation polymerization of acrolein in the bulk state was studied, and it was found that the microspheres of polyacrolein particles were formed in the absence of an emulsifing agent. The polymerization yield curve as a function of irradiation temperature had a break point at an irradiation temperature range of −20 to 0°C, in which an increase in particle size was observed. The size of the particles varied with irradiation temperature. Particles formed at low and high temperatures were relatively small. The size of particles formed in O 2 or under air bubbling conditions increased markedly with increasing irradiation dose, and that formed in an air atmosphere without air bubbling increased slightly with increasing irradiation dose. The particles formed under O 2 bubbling conditions had a narrow size distribution. The polymer structure was elucidated by IR spectrophotometry by which the aldehyde group concentration was monitored. The aldehyde content of the particles decreased with increasing irradiation dose. It was confirmed that polyacrolein particles having aldehyde groups can be bound easily to antibodies such as goat anti-rabbit IgG labeled with peroxidase. It was shown that polyacrolein particles can yield important immunoreagents for biological research.

Preparation of functional polymer‐microspheres by suspension copolymerization of ethylene glycol dimethacrylate with hydrophilic monomers

AbstractA study was made of suspension copolymerization of ethylene glycol dimethacrylate (EDMA) with some hydrophilic monomers (M2) to prepare gel particles having a large number and various kind of functional groups on their surface. Delayed charge of M2 to partially prepolymerized EDMA suspension resulted in the formation of favorable particles. The polymerization leveled off despite an appreciable amount of remaining M2 in the aqueous phase, and the amount of copolymerized M2 and the fraction of on‐surface M2 units depended significantly on the kind of M2 as well as the mode of M2 charge. These dependences were explained in terms of the partition coefficient of M2 between EDMA and water and the monomer reactivity ratio.

Preparation of functional polymer microspheres by suspension copolymerization of diallyl phthalate with carboxylic monomers

A study was made of the suspension copolymerization of diallyl phthalate (DAP) and acrylic and methacrylic acid (AAc and MAc, respectively, which were charged after delay to the suspension of partially prepolymerized DAP) and the structure of resulting gel particles. In the copolymerization of DAP with AAc, the conversion of AAc leveled off despite an appreciable amount of AAc remaining in the aqueous phase, whereas in DAP–MAc copolymerization most MAc was polymerized in the particles. The particle structure depended significantly on the mode of comonomer charge. Earlier charge of the comonomer to the reaction system resulted in the formation of particles having comonomer unit-rich surface layer. This was interpreted in terms of phase separation through loosely crosslinked structure in the particles and supported by an adsorption test using a dye and the observation of surface structure of the particles. The timing of comonomer charge changed the amount of comonomer units in the surface layer from 0.06 to 0.60 mmole/g particle.

Light microscope identification of murine B and T cells by means of functional polymeric microspheres

Covalent bonding of purified antibodies to polymeric microspheres of 0.4 to 0.8 μm diameter yields conjugates which can be used to label lymphocytes in the light microscope. Nonadherent microspheres can be separated by means of a discontinuous density gradient and quantitative measurements of adherent microsphere distributions can be made through examination of Wright's stained dry mounts or through fluorescent microscopic examination of cells in suspension. In general the distributions of adherent microspheres on mouse splenic and thymic lymphocytes in direct or indirect labelling assays show good agreement with results obtained from fluorescent antibody techniques. In comparison to fluorescent antibody the use of these antibody-microsphere conjugates has the advantage of allowing direct correlations between the surface antigens of cells and their histologie morphology.

Functional polymeric microspheres based on 2-hydroxyethyl methacrylate for immunochemical studies.

Co gamma irradiation of 2-hydroxethyl methacrylate in the presence or in the absence of other acrylic monomers was found to constitute an effective technique for the synthesis of hydrophilic functional microspheres in the size range of approxumately 0.3 to 3 mu in diameter. The effect of monomer concentration, steric stabilization, and electrostatic interaction on the particle size was investigated. Experimental conditions were determined to obtain desired particle sizes of relatively narrow distribution. It was shown that particles may be formed without intermediate micelles, i.e., by homogeneous nucleation, and the rate of particle formation is affected primarily by the rate of particle coalescence in the initial stages of the reaction. When covalently bound to antibodies these microspheres were successfully used to label murine and human lymphocytes.