Sulfonated Microspheres Research Articles

Biocompatible Magnetic and Molecular Dual-Targeting Polyelectrolyte Hybrid Hollow Microspheres for Controlled Drug Release

Well-defined biocompatible magnetic and molecular dual-targeting polyelectrolyte hybrid hollow microspheres have been accomplished via the layer-by-layer (LbL) self-assembly technique. The hybrid shell was fabricated by the electrostatic interaction between the polyelectrolyte cation, chitosan (CS), and the hybrid anion, citrate modified ferroferric oxide nanoparticles (Fe3O4-CA), onto the uniform polystyrene sulfonate microsphere templates. Then the magnetic hybrid core/shell composite particles were modified with a linear, functional poly(ethylene glycol) (PEG) monoterminated with a biotargeting molecule (folic acid (FA)). Afterward the dual targeting hybrid hollow microspheres were obtained after etching the templates by dialysis. The dual targeting hybrid hollow microspheres exhibit exciting pH response and stability in high salt-concentration media. Their pH-dependent controlled release of the drug molecule (anticancer drug, doxorubicin (DOX)) was also investigated in different human body fluids. As expected, the cell viability of the HepG2 cells which decreased more rapidly was treated by the FA modified hybrid hollow microspheres rather than the unmodified one in the in vitro study. The dual-targeting hybrid hollow microspheres demonstrate selective killing of the tumor cells. The precise magnetic and molecular targeting properties and pH-dependent controlled release offers promise for cancer treatment.

Aggregation-Resistant Superparamagnetic Noncovalent Hybrid Multilayer Hollow Microcapsules in High Ionic Strength Media

In order to avoid the aggregation and/or fusion of the polyelectrolyte multilayer hollow microcapsules self-assembled via the noncovalent bonds, superparamagnetic polyelectrolyte hybrid hollow microcapsules surface-modified with polyethylene glycol (PEG) brushes were designed and fabricated. After the layer-by-layer (LbL) self-assembly of chitosan (CS) and citric acid-modified magnetic nanoparticles (Fe3O4–CA) as the polycation and the hybrid anion on the polystyrene sulfonate microsphere (PSS) templates, respectively, the aldehyde group terminated polyethylene glycol-4000 (APEG) was grafted onto the surface of the superparamagnetic polyelectrolyte hybrid multilayer coated template microspheres via the nucleophilic addition between the aldehyde groups of APEG and the amino groups of CS. Then, the modified superparamagnetic polyelectrolyte hybrid hollow microcapsules were obtained after the templates were removed by dialysis. It was found that the surface PEGylation could prevent aggregation among the hollow microcapsules in the media with high salt concentration by dynamic light scattering (DLS), besides the increase in biocompatibility. The technique developed is expected to realize the application of the polyelectrolyte multilayer hollow microcapsules in real physiological environments.

Synthesis of polyaniline/carbon black hybrid hollow microspheres by layer-by-layer assembly used as electrode materials for supercapacitors

The polyaniline (PAn)/carbon black (CB) hybrid hollow microspheres have been prepared by the layer-by-layer assembly technique alternately adsorbing of PAn and CB onto the polystyrene sulfonate microsphere templates after etching the templates by dialysis. The hollow structure of the obtained hybrid hollow microspheres was characterized by transmission electron microscopy, which indicated that the external diameter of the hollow microspheres was about 3.0μm. When the hybrid hollow microsphere were used as the electrode material for supercapacitors, the results showed that the specific capacitance increased with the increase in the adsorption numbers of PAn and CB, which was as high as 532Fg−1 at a charge–discharge current density of 10mAcm−2 in 1.0M H2SO4 electrolyte after alternately adsorbing of PAn and CB six times.

The relationship of interaction forces in the protein adsorption onto polymeric microspheres

The relationship between hydrophobic and electrostatic interactions in protein adsorption was studied with various sulfonated microspheres, and it was compared with carboxylated microspheres. Hydrophobic interaction governed the adsorption in the low sulfonated microspheres and electrostatic interaction did in the high sulfonated ones. The transition point was observed when the two forces were exactly balanced, but it was shifted to the left compared to the case of the carboxylated microspheres. The above adsorption experiments with different kinds of surface functionality revealed the following general mechanism of protein adsorption. The protein adsorption mainly occurs by hydrophobic interaction when the hydrophobic surface is slightly modified with weak or strong acid, while it primarily occurs by hydrogen bonding (or electrostatic) interaction when the surface is mostly modified with weak (or strong) acid. The adsorption by electrostatic interaction is higher than that by any other interactions, but the rate of adsorption is slowest.

Interpretation of protein adsorption phenomena onto functional microspheres

The relationship between hydrophobic and electrostatic interactions in protein adsorption was studied for the various sulfonated microspheres, and it was compared with that for carboxylated microspheres. Hydrophobic interaction governed the adsorption in the low sulfonated microspheres whereas electrostatic interaction governed it in the high sulfonated microspheres. The transition point was observed when the two forces were exactly balanced, but it was shifted to the left compared with the case of the carboxylated microspheres. The above adsorption experiments with different kinds of surface functionality revealed the following general mechanism of protein adsorption. The protein adsorption occurs mainly by hydrophobic interaction when the hydrophobic surface is slightly modified with weak or strong acid, while it occurs primarily by hydrogen bonding (or electrostatic) interaction when the surface is mostly modified with weak (or strong) acid. Adsorption by electrostatic interaction is higher than that by any other interactions, but the rate of adsorption is slowest. Bovine serum albumin adsorbed onto carboxylated microspheres always undergoes an irreversible conformational change to the end-on mode, while this would not occur around the transition point in the case of the sulfonated microspheres.