Nanosphere characterization

Various techniques can be used for the characterization of surface-modified nanoparticles (Muller, 1991). In the case of PEG-covered nanospheres, atomic force microscopy and freeze-fracture have been used to determine their morphology, light scattering has been employed to measure their size, and surface analysis techniques have been applied to detect the presence of PEG on the surface and the stability of this coating, etc. Some of these techniques are presented in this section. 

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Another nice example of nanostructuring an MIP layer is the work published by Wu et al. [138, 139] who developed a label-free optical sensor based on molecularly imprinted photonic polymers. Photonic crystals were prepared by self-assembly of silica nanospheres. The space between the spheres was then filled with MIP precursor solution. After polymerization, the silica was dissolved, leaving an MIP in the form of a 3D-ordered interconnected macroporous inverse polymer opal (Fig. 15). The authors were able to detect traces of the herbicide atrazine at low concentrations in aqueous solution [139]. Analyte adsorption into the binding sites resulted in a change in Bragg diffraction of the polymer characterized by a color modification (Fig. 15). 

Blanco, M. D., and Alonso, M. J. (1997), Development and characterization of protein-loaded poly(lactide-co-glycolide) nanospheres, Eur. J. Pharrn. Biopharm., 43, 287-294. 

Peroche, S., Degobert, G., Putaux, J. L., Blanchin, M. G., Fessi, H., and Parrot-Lopez, H. (2005), Synthesis and characterization of novel nanospheres made from amphiphilic perfluoroalkylthio-B-cyclodextrins, Eur. J. Pharm. Biopharm., 60,123-131. 

Monodisperse polystyrene (latex) spheres having a radius value in the range 30-100 run with a standard deviation of 8% or less characterizing the size uniformity. Such samples can be obtained from Duke Scientific Corp. as 3000 Series Nanospheres (www. dukescientific.com), Polymer Laboratories as PL-Latex Plain White (www.polymerlabs. com), and Polysciences, Inc., as Nanobead Traceable Size Standards (www.polysciences. com). 

Ravi Kumar M N V, Bakowsky U, Lehr C M (2004). Preparation and characterization of cationic PLGA nanospheres as DNA carriers. Biomaterials. 25 1771-1777. 

Ha JC, Kim SY, Lee YM. Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)(plueronic/poly(e-caprolactone) (PCL) amphiphilic block copolymeric nanospheres I. Preparation and characterization. J Contr Rel 1995 62 381-392. 

A. D. Ormonde, E.C. M. Hicks, J. Castillo, and R. P. Van Duyne, Nanosphere Lithography Fabrication of Large-Area Ag Nanoparticle Arrays by Convective Self-Assembly and their Characterization by Scanning UV-Visible Extinction Spectroscopy, Langmuir 20, 6927 (2004)... 

Liu XQ, Guan YP, Ma ZY, et al. (2004) Surface modification and characterization of magnetic polymer nanospheres prepared by miniemulsion polymerization. Langmuir 20 10278-10282... 

B. Sreedhar, P. Radhika, B. Neelima, N. HehaUcar, and M. V. B. Rao, Synthesis and characterization of polyaniline nanospheres, nanorods, and nanotubes-catalytic application for sulfoxidation reactions, Polym. Adv. Technol, 20, 950-958 (2008). 

S.B. Han, A.L. Briseno, X. Shi, D.A. Mah, F. Zhou, Polyelectrolyte-coated nanosphere lithographic patterning of surfaces Fabrication and characterization of electropolymerized thin polyaniline honeycomb films, J. Phys. Chem. B, 106(25), 6465-6472 (2002). 

Liu, X., Ma, Z., Xing, J., and Liu, H. Preparation and characterization of amino-silane modified super-paramagnetic silica nanospheres. J. Magnetism Magnet. Mater. 270 (2004) 1-6. 

Mukerjee A, Vishwanatha JK. Formulation, characterization and evaluation of curcumin-loaded PLGA nanospheres for cancer therapy. Anticancer Res. 2009 29(10) 3867-3875. 

Robinson DN, Peppas NA (2002) Preparation and characterization of pH-responsive poly (methacrylic acid-g-ethylene glycol) nanospheres. Macromolecules 35 3668... 

Aiping, Z., Tian, C., Lanhua, Y, Hao, W., and Ping, L. 2006. Synthesis and characterization of JV-sncdnyl-chitosan and its self-assembly of nanospheres. Carbohydr. Polym. 66 274-279. 

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