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Objective. To develop a real-time imaging method to identify the rat stomach lymph node basin with quantum dots (Qdots). Material and methods. Six Sprague-Dawley rats received injections of 0.05 ml Qdots (1 mg/ml) in the subserosal layer in the lesser curvature of the gastric antrum. Subsequently, draining lymphatic channels and lymph nodes were visualized with a near-infrared fluorescence imaging system. Histological examination was required to confirm the presence of lymph nodes. Additionally, rats received injections of Qdots and underwent 2 weeks of observation to confirm if there was any abnormality. The distribution of Qdots was measured by inductively coupled plasma-mass spectrometry. Results. After injection of the Qdots, the gastric sentinel lymph nodes were visualized 15 min later. The fluorescence then began to spread. The intensity of fluorescence increased in the perigastric area at 60 min, and declined at 360 min. Histological analysis of the fluorescent tissue confirmed the presence of nodal tissue. The results of a cadmium assay showed that Qdots were mainly distributed in the liver, spleen and kidney of the rats. No apparent toxicity could be seen during the 2 weeks of observation. Conclusions. NIR fluorescence imaging of lymph nodes with Qdots is a novel and reliable real-time technique that can be used to assist with identification and resection of stomach lymph nodes. The optimal observation time of perigastric SLNs was 15 min after the injection, and the optimal observation time of perigastric lymph nodes beyond the SLNs was 60-120 min after the injection. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Nanoscale poly(cyclohexyl methacrylate) (PCHMA) particles were prepared by a modified microemulsion polymerization procedure. 13C-NMR analysis suggested that such PCHMA samples were higher in syndiotactic content (61-72% rr) and lower in isotactic content (1-3% mm). The glass transition temperatures (Tg's) of the products were also higher than that reported in the literature. The polymer properties, such as particle size, molecular weight, tacticity, and Tg were affected by the reaction conditions. The smaller the particle size, the higher the syndiotacticity, the lower the isotacticity and the greater the molecular weight, then the higher the Tg of the PCHMA samples. Possible mechanism of rich-syndiotacticity was also discussed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Modified microemulsion polymerization is a useful method to prepare nanoscale poly(methyl methacrylate) (PMMA) latex with a high solid content (10–30 wt%) and nanoscale (20–40 nm) particles by only using 1–2 wt% surfactant. The main feature of modified microemulsion polymerization is that most of the monomer is post‐added gradually into the initiated pre‐microemulsion, and the surfactant can be utilized adequately. We find that the polymerization rate increases with the increasing of the post‐addition rates, using the Mettler Toledo Reaction Calorimeter to accurately record the heat of reactions and calculate data. Furthermore, after analyzing the products in GPC, the post‐addition rate is found to significantly influence the molecular weight of polymer: the molecular weight also increases with the increasing of the post‐addition rate. [ABSTRACT FROM AUTHOR]

Semi-transparent reactive microgel in nanosize has been prepared by modified microemulsion polymerization using a common emulsifier, crosslinking agent and functional monomer. The microgels are translucent reactive nanoparticles, with the size of 40–100 nm, consisting of inner-crosslinked polymer up to 40%. FT-IR proved the functional groups, such as epoxy and hydroxy, are on the surface of the microgel nanoparticles. Rheological detection demonstrated the apparent pseudoplasticity of the non-aqueous microgel dispersion prepared by the phase transfering from the O/W microlatexes. [ABSTRACT FROM AUTHOR]

Nanoscale poly(ethyl methacrylate) (PEMA) particles were prepared by a monomer post-added microemulsion polymerization procedure. ¹H NMR analysis suggested that the PEMA samples were rich in syndiotactic content (58-64% rr) and lower in isotactic content (4-6%mm). The glass transition temperatures (Tg's) of the products were also higher than those of the PEMA samples prepared by ordinary free-radical polymerization. The polymer properties, such as particle size, molecular weight, tacticity, and Tg were affected by the reaction conditions. The smaller the particle size, the higher the syndiotacticity, the lower the isotacticity, the greater the molecular weight, then the higher the Tg of PEMA. A possible mechanism of rich-syndiotacticity was also discussed primarily. [ABSTRACT FROM AUTHOR]

A fluorophore-enriched polymer was synthesized through modification of a kind of copolymer by fluorescein isothiocyanate (FITC). The copolymer was obtained by batch emulsion polymerization of t-butyl acrylate (t-BA) and an amino-containing monomer M2, which was produced in our laboratory. According to various characterizations, such as gel permeability chromatography (GPC), 1H-NMR, fluorescence spectroscopy, the amount of amino and fluorescein groups of the obtained fluorescent polymer could be controlled and its polarity could be converted from hydrophobic to hydrophilic through hydrolysis. These water-soluble fluorescent polymers had a high luminescence, which were visible under the conventional microscope. Such an advantage made them suitable for further bioconjunction as probes with their targets, such as biomacromolecules and cells. [ABSTRACT FROM AUTHOR]

A series of hexylamine modified polysuccinimide (PSI–HA) copolymers were synthesized by aminolysis of polysuccinimide (PSI) with hexylamine. FTIR and 1H NMR measurements confirmed the structure of the copolymers and the substitution degree of the N-hexyl aspartamide units ranged from 7 to 92 mol%. Stable nanoparticles formed when the DMF solution of PSI–HA copolymers was dropped into excess water, and the particle size reduced as increasing the substitution degree. 1H NMR analysis indicated that hexyl chain and succinimide units interacted to form the hydrophobic core, while, the nanoparticles were stabilized by the amide groups which formed hydrogen bonds with the surrounding water molecules. The nanoparticles became more compact at higher temperature due to the break of hydrogen bonds between amide groups and water molecules. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) results showed that the nanoparticles were nearly spherical. Larger nanoparticles formed when the dispersion concentration increased from 0.1% to 1.0% according to the DLS and steady-state fluorescence measurements. After the nanoparticles formed in water, a sequential dilution can't influence the particles size of the nanoparticles any longer. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Copolymer microspheres consisting of styrene and N-vinyl carbazole (NVC) have been prepared by dispersion polymerization. The effects of various polymerization parameters on the particle size were systematically studied. The particle size increased with the decrease of the system's initial solubility parameter and stabilizer concentration. When a small amount of inhibitor was added into the system, the particle size notably increased and the particle size distribution widened. The ratio of styrene to NVC in the monomer mixture had no obvious effect on particle size. The amount of NVC in the copolymers increases with the increase of NVC in the monomers. [ABSTRACT FROM AUTHOR]