Shoukuan Fu

Magnetic mesoporous silica microspheres with thermo-sensitive polymer shell for controlled drug release

A controlled drug release system was designed based on the combination of three advantages into one entity, which was composed of Fe3O4 magnetic nanoparticle as the core, mesoporous silica as the sandwiched layer, and thermo-sensitive P(NIPAM-co-NHMA) copolymer as the outer shell. The hydrophilic comonomer content affected the volume phase-transition temperature (VPTT) of this composite microsphere and the behavior of the temperature-triggered drug release. Zn(II) phthalocyanine tetrasulfonic acid (ZnPcS4), a well-known photodynamic therapy (PDT) drug, was used as a model drug to assess the release system. The results demonstrated that the drug release behavior was dependent on the temperature and had a close correlation with the VPTT. Above the VPTT, the drug release rate was much faster than that below the VPTT, which showed a great potential application in tumor therapy.

High solids-content nanosize polymer latexes made by microemulsion polymerization

Polymer nanoparticles were prepared from monomers such as styrene (St), butyl methacrylate (BMA), butyl acrylate (BA), methyl methacrylate (MMA), and methyl acrylate (MA) using a modified microemulsion polymerization process. With this process high polymer: surfactant weight ratios (7 : 1 or greater), relatively concentrated (10–30 wt.-%) latexes and small (10–20 nm) particle diameters were attained. Nucleation mechanisms were investigated through observations of the particle size change during the polymerization.

The brain targeting efficiency following nasally applied MPEG-PLA nanoparticles in rats

The aim of this study was to encapsulate nimodipine (NM) within methoxy poly(ethylene glycol)-poly(lactic acid) (MPEG-PLA) nanoparticles and to investigate its brain targeting efficiency following intranasal administration. NM-loaded nanoparticles, prepared through an emulsion/solvent evaporation technique, were characterized in terms of size, zeta potential, NM loading and in vitro release. The nanoparticles were administered intranasally to rats, and the concentrations of NM in blood, cerebrospinal fluid (CSF) and brain tissues were monitored. The contribution of the olfactory pathway to the uptake of NM in the brain was determined by calculating the brain/plasma concentration ratios and “brain drug direct transport percentage (DTP)” following intranasal administration of the nanoparticles and the solution formulation. The results showed that MPEG-PLA nanoparticles had a mean particle size of 76.5 ± 7.4 nm, a negative surface charge and a 5.2% NM loading. In vitro release was moderate under sink conditions. The intranasal administration of nanoparticles resulted in a low but constant NM level in plasma. The ratio of AUC values of the nanoparticles to the solution was 1.56 in CSF. The olfactory bulb/plasma and CSF/plasma concentration ratios were significantly higher (P < 0.05) after application of nanoparticles than those of the nasal solution, except the ratio in olfactory bulb at 5 min. Furthermore, nasally administered nanoparticles yielded 1.6–3.3-fold greater DTP values in CSF, olfactory bulb and other brain tissues compared to nasal solution. Thus, MPEG-PLA nanoparticles demonstrated its potential on improving the efficacy of the direct nose–brain transport for drugs.

Preparation, characterization and application of magnetic silica nanoparticle functionalized multi-walled carbon nanotubes

Magnetic silica nanoparticle functionalized multi-walled carbon nanotubes (MS-MWNTs) were prepared, characterized and used for the convenient, rapid and efficient separation of trace aromatic compounds.

LAYER-BY-LAYER ASSEMBLY OF NANOZEOLITE BASED ON POLYMERIC MICROSPHERE: ZEOLITE COATED SPHERE AND HOLLOW ZEOLITE SPHERE

ABSTRACT Zeolite β, silicalite-1, ZSM-5, and TS-1 coated spheres have been prepared successfully through layer-by-layer assembly of nanozeolite/polymer multilayers on polystyrene (PS) microspheres, and hollow zeolite spheres have been obtained by removal of the core by calcination. In the adsorption process of nanozeolites onto the polyelectrolyte-modified template spheres, it has been found that zeta potential of the zeolite colloidal solution that determines the electrostatic interaction has important effects on the zeolite adsorption procedure. The charge on the original sphere template is not necessary, because proper polyelectrolyte modification could change the surface property of the template and make it suitable for layer-by-layer adsorption. The influences of zeolite type and/or size (40–120 nm), the number of zeolite/poly(diallyl-dimethyl-ammonium) layer pairs, and the template sphere size (0.53–10.3 µm) on the preparation of the hollow zeolite spheres were also discussed.

Dispersion copolymerization of styrene and other vinyl monomers in polar solvents

Dispersion polymerization is a very attractive method for preparing micrometer-size monodisperse polymer particles. The applications of microspheres have been greatly expanded by the use of copolymers. Here, the dispersion copolymerization of styrene and seven other vinyl monomers was carried out in polar solvents. The effect of the different comonomers on the particle size was systematically investigated. The particle size first decreased and then increased with an increasing fraction of acrylamide in the monomer feed, and at a higher fraction of such a comonomer, only a gel-like polymer was obtained. The particle size also increased with the increase in the contents of the hydrophilic comonomers in the monomer mixtures, and the copolymer molecular weight decreased meanwhile. Although the amount of the hydrophobic comonomer in the monomer mixture changed, the particle size was hardly affected.

Synthesis of C60 end-capped polymers from azide functional polystyrene via Atom transfer radical polymerization

Atom transfer radical polymerization (ATRP) was performed to prepare azide end-functional polystyrene (PSt-N3) with predesigned molecular weight and narrow polydispersity. Then C60 end-capped polystyrene was synthesized by reacting C60 with PSt-N3. The UV-VIS, DSC, GPC characterizations indicated that C60 was chemically bonded to the end of polystyrene chain, and the brown powder products, which can be dissolved in THF, CHCl3, DMF, and so forth, were monoadditional and diadditional according to C60.

Synthesis and Striking Fluorescence Properties of Hyperbranched Poly(amido amine)

Hyperbranched poly(amido amine) (h‐PAMAM) was synthesized from different feed ratios of diethylene triamine and methyl acrylate by the simple one‐pot and commercial synthesis method. Reaction procedures and products were intensively studied by FTIR, inherent viscosity and fluorescence techniques. The ill‐structured h‐PAMAM shared similar chemical and physical properties with well defined poly(amido amine) (PAMAM) dendrimers in generation 2 or 3. Its strong fluorescence properties were influenced by pH values, solvents, concentrations, terminal groups and other factors.

Synthesis and characterization of the narrow polydispersity fullerene-end-capped polystyrene

SummaryA living free radical polymerization process was adopted to synthesize a narrow polydispersity fullerene-end-capped polystyrene(NPFECPS). The UV-Vis, DSC, GPC demonstrated that fullerene(C60) was chemically bonded to polystyrene successfully, and C60 was almost monosubstituted. The NPFECPS can be dissolved in a variety of solvents, such as THF, toluene, trichloromethane, and so on. The good photoconductivity is also found for NPFECPS.

The Relationship of Reaction Temperature, Tg and Rich‐Syndiotacticity of Poly(alkyl methacrylate)s in Modified Microemulsion Polymerization

Nanoscale poly(alkyl methacrylate)s including poly(methyl methacrylate), poly(ethyl methacrylate), poly(cyclohexyl methacrylate), poly(iso‐butyl methacrylate) and poly(benzyl methacrylate) were prepared by a modified microemulsion polymerization procedure. NMR analysis suggested that these poly(methacrylate)s samples were higher in syndiotactic content, lower in isotactic content and the glass transition temperatures (Tgs) of them were also higher than those reported in the literature. The tacticities of the poly(methacrylate)s, beside the restricted volume effect of nanoparticles during the modified microemulsion polymerization, were mainly influenced by the reaction temperature, the lower the reaction temperature, the higher the syndiotacticity of the products. The syndiotacticity of the product decreased obviously when the polymerization was carried out at a temperature far above the Tg of the resulting polymer. It was also shown that the tacticity of the polymer was affected by the monomer structure, a monomer with the bulkier alkyl side group would liable to result in a polymer with richer syndiotacticity. Possible mechanism of rich‐syndiotacticity was also discussed.