Superparamagnetic pH‐sensitive multilayer hybrid hollow microspheres for targeted controlled release

Abstract

The superparamagnetic multilayer hybrid hollow microspheres have been fabricated using the layer-by-layer assembly technique by the electrostatic interaction between the polyelectrolyte cation chitosan (CS) and the hybrid anion citrate modified ferroferric oxide nanoparticles (Fe 3 O 4 -CA) onto the sacrificial polystyrene sulfonate microspheres templates after etching the templates by dialysis. The saturation magnetization and magnetite contents of the superparamagnetic multilayer hybrid hollow microspheres were 32.46 emu/g and 51.3%, respectively. The hybrid hollow microspheres showed pH-sensitive characteristics. The adsorption and release of the basic dye (methylene blue) were applied to investigate the interaction between the amino groups of CS and the carboxyl groups of the Fe 3 O 4 -CA nanoparticles in different pH media. The superparamagnetic pH-sensitive multilayer hybrid hollow microspheres are expected to be used for the targeted controlled release of drugs or in diagnostics. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3135-3144, 2010 KEYWORDS: hybrid hollow microspheres; layer-by-layer assembly; pH sensitive; superparamagnetic; targeted controlled releaseRecently, surface-charged nanoparticles have been used for the fabrication of the multilayer hybrid hollow microspheres.

Green oxidation of alcohols by using hydrogen peroxide in water in the presence of magnetic Fe3O4nanoparticles as recoverable catalyst

“…In most cases, the aldehyde selectivity was quite high (>99%) and the competing reaction such as overoxidation of aldehydes to the corresponding carboxylic acids was not observed, either. The oxidation of various benzylic alcohols gave the carbonyl compounds in high yields and short reaction times in comparison with the other procedures (17). The oxidation time for aliphatic alcohols was long.…”

“…The search for catalytic oxidation of alcohols in an aqueous medium in the absence of an additional base is still a significant challenge (16). Among the numerous methods in the synthetic organic chemistry, free nano Fe 2 O 3 is the most promising; but overoxidation of nano Fe 2 O 3 catalyst is accomplished at high temperatures and long reaction times (17).…”

Layer-by-Layer Engineered Superparamagnetic Polyelectrolyte Hybrid Hollow Microspheres With High Magnetic Content as Drug Delivery System

“…The polystyrene sulfonate (PSS) microspheres and the citrate modified ferroferric oxide (Fe 3 O 4 -CA) were prepared according to the procedure reported previously [16]. The layer-by-layer assembly technique was used to prepare the multilayer magnetic polyelectrolyte hybrid hollow microspheres.…”

“…The nanometer scaled C60-like Keplerate type (Mo 72 Fe 30 ) [13] and the magnetite (Fe 3 O 4 ) nanoparticles [14] were also deposited as the interlayer in the polyelectrolyte bilayers to fabricate the magnetic microcapsules using the LbL technique. Liu et al [15] fabricated several magnetic polyelectrolyte hybrid multilayer hollow microspheres via the LbL assembly with one natural biocompatible polyelectrolyte (alginate or chitosan) and the pristine Fe 3 O 4 nanoparticles, or the citrate modified ferroferric oxide nanoparticles (Fe 3 O 4 -CA) as hybrid anion [16][17][18].…”

“…So in the preparation of the CS-PEG-(Fe 3 O 4 -CA=Fe 3 O 4 -LYs) 4 -CS-PEG hollow microspheres, the copolymer CS-PEG layers acted as the stabilizer for the magnetic shells [12]. Furthermore, at low pH media, the ionization of the carboxyl groups of the Fe 3 O 4 -CA nanoparticles was normally depressed and the amino groups in CS-PEG and the Fe 3 O 4 -LYs nanoparticles were protonated [16]. It is favorable to the drug-release in the media with lower pH values such as the acidic tumor microenvironments [29].…”