Multilayer microsphere

Polyelectrolyte multilayer microspheres, prepared by alternating adsorption of dextran sulfate and protamine on melamine formaldehyde cores followed by the partial decomposition of the core, were used to immobilise the peroxidase and glucose oxidase. Retention of enzymic activity of the peroxidase/glucose oxidase system incorporated into the microspheres was demonstrated. These bienzyme system immobilised in the microspheres can be applied for kinetic glucose assays [ 156]. 

Scheme 15.12. Synthesis of PAMAM dendrons on multilayer microspheres.

In recent years, PAMAM on polystyrene was also synthesized by other groups. " A similar methodology was used by Wang and coworkers to assemble PAMAM dendrons on multilayer microspheres consisting of a magnetite core covered by an intermediate methyl methacrylate-divinylbenzene polymer shell and polyglycidyl methacrylate outer layer (Scheme 15.12)." ... 

Coatings for inertial confinement microsphere targets comprised of multilayers of Be, Au, Pt, and Ta.P l... 

Teraoka, I. Arnold, S., Coupled whispering gallery modes in a multilayer coated microsphere, Opt. Lett. 2007, 32, 1147 1149... 

Carty, P. White, S. Price, D. Lu, L. (1999) Smoke suppression in plasticised chlorinated poly(vinyl) chloride (CPVC). Polymer Degradation Stability 63 465-468 Caruso, F. Susha, A.S. Giersig, M. Moh-wald, H. (1999) Magnetic core-shell particles Preparation of magnetite multilayers in polymer latex microspheres. Adv. Mater. 11 950-952... 

In a few studies sonochemistry was used to coat polymers with nanosized par-tides [48-50]. Of these three reports one [50] dealt with metals, more specifically with noble metals (Pt, Pd, and Au). In this research, metal colloids are adsorbed to the surface of neutral functionalized polystyrene microspheres, PSMS. The authors report on the synthesis and characterization of catalytically important noble monometallic colloids using various chemical and sonochemical methods. These metal colloids are then adsorbed onto suitably functionalized PSMS. The metal-immobilized microspheres are reacted with a linker such as 4-mercaptobutyl phosphonic acid and subsequently used to grow multilayers. 

Zhou J, Chen M, Qiao XG, et al. (2006) Facile preparation method of Si02/PS/Ti02 multilayer core-sheU hybrid microspheres. Langmuir 22 10175-10179... 

Srivastava R, Brown JQ, Zhu HG, et al. (2005) Stable encapsulation of active enzyme by application of multilayer ntmofilm coatings to alginate microspheres. Macromol Biosci 5 717-727... 

In encapsulation process, microspheres and microcapsules can be obtained. Microspheres are microbeads composed of a biopolymer gel network entrapping an active, whereas microcapsules are constituted by an active ingredient (small droplets of liquid or particles) that is inside a hollow and involved by thin walls(s) (Madene et al 2006 Umer et al 2011). The simplest of the microcapsules may have a core surrounded by a wall of uniform or nonuniform thickness. The core material may have one or several different types of ingredients. The wall may be single or multilayered (Madene et al., 2006). 

Multiple purpose systems also include multiple wall or layered microspheres. An interesting multilayer microcapsule (microsphere) was first prepared by Mathiowitz and Langer " in a single step process. The approach relies in on a modification of Harkin s equation for spreading equilibrium... 

In this chapter, we introduce the ESA modified membranes by forming electrostatic alternate layers of cetyl trimethyl ammonium chloride (CTAC) and poly(acrylic acid) (PAA) onto charged copolyacrylonitrile membranes (Scheme 1). Along with surface characterization of the ESA multilayer, infrared analysis was carried out. Finally, we evaluated the adsorptive properties of ESA multilayer for Fe and Fe, and ESA membranes with chitosan microspheres / PAA for removing of Cu2+. 

In order to confirm the fabrication of the multilayer of chitosan or chitosan microsphere and PAA layers. Here, the FTIC labeled-chitosan and PAA layers were alternatively deposited onto charged glass slide for UV-vis measurement (Scheme 4-3). 

However, much less change in the surface roughness was observed for the membrane with chitosan/PAA ESA layers. The values of the surface roughness were 8.0 nm, 8.6 nm, 9.0 nm, 12.2 nm, and 13.7 nm for the cycled layers of 0, 1, 2, 3 and 4, respectively. Therefore, the introduction of the chitosan microspheres for the ESA multilayer could be effectively for roughing the base of membrane surfaces. Therefore, this approach could be attractive in the uses of adsorption of such metal ions. 

Especially the chitosan microspheres/PAA system demonstrated low adsorption at pH 7. This meant that the increase of the solution pH restrained the coordination of Cu2+ ions, which was induced by the destruction of the ESA multilayer at pH 7. However, at pH 5 and 6, partial amino group remained on the protonation form which was favorable for the stability of chitosan or chitosan microspheres layers on resultant membranes. Also, Figure 4-7 was plotted for comparing the adsorption capacity of resultant membranes with chitosan/PAA ESA layers and chitosan microspheres/PAA ESA layers. It was seen that... 

DDS systems may be ascribed to more than one type, e.g. nanoparticles or microspheres coated with multilayer films. Cationic polymers are extensively used in nucleic acid delivety and the respective delivery systems may also be considered as DDSs. However, since non-viral nucleic acid delivery with a great potential in gene therapy has become such an intensively studied area, it is out of the scope of the present chapter. 

Sukhorukov, G.B., Multilayer Hollow Microspheres, in Dendrimers, Assemblies. Nanocomposites, MML Series, Arshady, R. and Guyot, A., Eds., Citus Books, London, 2002, pp. 111-147. 

Uniform PANI thin shells and hollow capsules have been formed using polyelectrolyte-coated microspheres as a template [285]. Multilayers of poly (diallyldimethylammonium chloride) and PSS pre-coated onto melamine formaldehyde particle via the LBL self-assembly procedure was used as a template for the subsequent deposition of PANI. 

A possibility to consider polyciystalline platinum surface as some combination of low index surfaces or as some disordered single crystalline surface surely caimot be immediately concluded from the values of zero charge potentials exclusively. Experiments with some intermediate model systems more or less reduceable to simple additive combinations of several planes, or of terraces and steps, are of increasing interest. Microfacetted electrodes, various types of nanoparticles prepared by precise non-electrochemical techniques, non-coalesced electrodeposited particles, " and single platinum microspheres deposited on micro-electrodes, as well as highly ordered templated electrdeposits can be considered as most ordered real platinum materials helpful to discover stractural effects at atomic level. However they all are still too simple to compare with, to say, platinized platinum, and attempts to electrodeposit the dispersed metallic multilayers of more and more ordered type ° are also relevant. 

J. Lee, M. Senna, Preparation of monodispersed polystyrene microspheres uniformly coated by magnetite via heterogeneous polymerization. Colloid Polym. Sci. 1995,273, 76-82 (c) F. Camso, A.S. Susha, M. Giersig, H. Moh-wald. Magnetic core-shell particles preparation of magnetite multilayers on polymer latex microspheres, Adv. Mater. 1999, 11,950-953. 

Xu C, Xu G, Liu Y, Zhao X, Guanghou WG (2002) Preparation and characterization of SnO nanorods by thermal decomposition of SnC O precursor. Seri Mater 46 789-794 Yang HX, Qian JF, Chen ZX, Ai XP, Cao YL (2007) Multilayered nanocrystaUine SnO hollow microspheres S3mthe-sized by chemically induced self-assembly in the hydrothermal environment. J Phys Chem 111 14067-14071 Yuan L, Hyodo T, Shimizu Y, Egashira M (2011) Preparation of mesoporous and/or macroporous SnO -based powders and their gas-sensing properties as thick film sensors. Sensors 11 (2) 1261-1276 Yue W, Zhou W (2008) Crystalline mesoporous metal oxide. Progr Nat Sci 18 1329-1338... 

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