• Archives of Pharmacal Research
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• v.9 no.3
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• pp.145-152
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• 1986

Magnetically reponsive gelatin microspheres for the targeting of drugs have been prepared using a water-in-oil emulsion technique with chemical cross-linking of the protein. The manufacturing variables affecting microsphere size, size distribution and surface characteristics have been examined as well as the magnetic responsiveness in vitro. Sesame oil was utilized for non-aqueous phase and magentic gelatin microspheres of different size from 1. 89 to 14.88 $\mu\textrm{m}$ in mean diameter could be obtained with variation of HLB values of non-ionic surfactants. The content of magnetite which uniformly distributed throughout the microspheres was 26.7% (w/w). It was possible to control the localization of magnetic gelatin microspheres at specific sites within capilary models by using external magnetic field of under 5K gauss.

• Biomolecules & Therapeutics
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• v.17 no.1
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• pp.98-103
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• 2009

Superparamagnetic iron oxide nanoparticles (SPIOs)-embedded chitosan microspheres were developed for magnetic resonance (MR)-traceable embolotherapy. SPIOs-loaded chitosan microspheres were prepared by emulsion and cross-linking technique and 100-200 ${\mu}m$ sized spherical microsparticles were obtained. Loading efficacy and loading amount of SPIOs in microspheres were about 40% and 0.26-0.32%, respectively, when measured by inductively coupled plasma atomic emission spectroscopy. Within 30 days, about 60% of the incorporated SPIOs were released from low cross-linked microspheres, whereas only about 40% of SPIOs was released from highly cross-linked microspheres. Highly cross-linked microspheres were more efficient for lower degree of swelling leading to secure entrapment of SPIOs in matrix. Prepared novel embolic microspheres are expected to be practically applicable for traceable embolotherapy with high resolution and sensitivity through magnetic resonance imaging (MRI).

• Archives of Pharmacal Research
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• v.16 no.4
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• pp.312-317
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• 1993

To confirm a new evaluation tedhnique for biodegradability of biopolymer microsphers in vivo condition, magnetic microsphere sytem was adopted for tracing the microspheres injected and lodged in micr. Microsphers of poly(DL-lactic acid), poly(L-alctic acid) and poly(DL-lactide-coglycolide)(PLGA) were prepared by solvent-extraction method and their organ distribution and biodegradation in mice was examined. Magnetic microspheres lodged in mice organs were recollected from the homogenates of mice organs with a constant flow magnetic separation apparatus. Recollected microspheres were observed by scanning electron microscopy and also were assayed for their magnetite ocntent by atomic absorption spectrophotometry to evaluate the biodegradability of polymeric microspheres. This method seems to be practical and simple to estimate the biodegradability of biopolymers over the conventional methods.

• Nano
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• v.13 no.11
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• pp.1850128.1-1850128.10
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• 2018

Glutathione (GSH), the protective agent and reducing agent, has been widely used to prepare gold nanoclusters (GSH-Au NCs) with stable fluorescence properties and negative charge of the surface. Meanwhile, polyethyleneimine (PEI) was used as the modification agent to synthesize magnetic ferroferric oxide nanoparticles ($Fe_3O_4$) with fantastic dispersibility and positive charge of the surface. Based on the electrostatic adsorption force, magnetic nano-$Fe_3O_4@GSH-Au$ NCs core-shell microspheres composed of magnetic $Fe_3O_4$ nanoparticles modified by PEI as the core and GSH-Au NCs as the shell were assembled. The prepared $Fe_3O_4@GSH-Au$ NCs microspheres harbored a uniform size (88.6 nm), high magnetization (29.2 emu/g) and excellent fluorescence. Due to the coordination bond action between Au atom and sulfhydryl (-SH), amino ($-NH_2$), carboxyl (-COOH) in sweat, $Fe_3O_4@GSH-Au$ NCs could combine with latent fingerprints. In addition, $Fe_3O_4@GSH-Au$ NCs with good fluorescence and magnetism could detect fingerprints on various objects. Significantly, the powders were not easy to suspend in the air, which avoided the damage to the health of forensic experts and the fingerprints by only powder contacting. Above all, $Fe_3O_4@GSH-Au$ NCs was successfully applied to the latent fingerprint visualization, which has great potential in forensic science.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.05
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• pp.7-14
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• 1993

Nowadays, microspheres are expected to be applied to biomedical areas and many studies are being performed. For biomedical applications, many kinds of microspheres were synthesized by emulsion polymerization, emulsifier-free emu]sion polymerization, and emulsifier-free emulsion polymerization with ionic surface-active comonomers. Further synthesis techniques about microencapsulation and magnetic microspheres are introduced. Among the practical applications of microspheres, some interesting subjects are introduced. These include solid-phase immunoassays, labeling and identification of lymphocyte populations, extracorporeal and hemoperfusion systems, drug delivery systems, and immunomagnetic cell separation. In addition, basic theories, problems and research trends are also introduced.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.172-177
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• 2017

A novel biosorbent, immobilized Saccharomyces cerevisiae in magnetic chitosan microspheres was prepared, characterized, and used for the removal of $Sr^{2+}$ from aqueous solution. The structure and morphology of immobilized S. cerevisiae before and after $Sr^{2+}$adsorption were observed using scanning electron microscopy with energy dispersive X-ray spectroscopy. The experimental results showed that the Langmuir and Freundlich isotherm models could be used to describe the $Sr^{2+}$ adsorption onto immobilized S. cerevisiae microspheres. The maximal adsorption capacity ($q_m$) was calculated to be 81.96 mg/g by the Langmuir model. Immobilized S. cerevisiae was an effective adsorbent for the $Sr^{2+}$ removal from aqueous solution.

• Journal of the Korean Magnetics Society
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• v.16 no.4
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• pp.221-227
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• 2006

We have synthesized uniform nanometer sized magnetite particles using chemical coprecipitation technique through a sonochemical method with surfactant such as oleic acid. Magnetite phase nanoparticles could be observed from X-ray diffraction. Magnetite nanoparticles is surface phase morphology and biopolymer-microspheres for Application Medical. Magnetite nanoparticles coated biopolymer. Atomic Force Microscope (AFM) was used to image the coated nanoparticles. Magnetic colloid suspensions containing particles with sodium oleate, chitosan and $\beta$-glucan have been prepared. The morphology of the magnetic biopolymer microsphere particles were characterized using optical microscope. Magnetic hysteresis measurement were performed using a superconducting quantum interference device (SQUID) magnetometer at room temperature to investigate the magnetic properties of the biopolymer microspheres and magnetite coated biopolymer including magnetite nanoparticles. Magnetic Resonance (MR) imaging was used to investigate biopolymer coated nanoparticles and biopolymer microspheres.

• Journal of the Korean Magnetics Society
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• v.15 no.2
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• pp.67-75
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• 2005

For th aim of lightweight microwave absorbers, conductive and magnetic microspheres are fabricated by plating of Co films on hollow ceramic microspheres of low density. Metal plating was carried out in a two-step electroless plating process (pre-treatment of activation and plating). Uniform coating of the film with about $2{\~}3{\cal}um$ thickness was identified by SEM. High-frequency magnetic and microwave absorbing properties were determined in the rubber composites containing the Co-coated microspheres. Due to conductive and ferromagnetic behavior of the Co thin films, high dielectric constant and magnetic loss can be obtained in the microwave frequencies. Due to those electromagnetic properties, high absorption rate (25 dB) and thin matching thickness ($2.0{\~}2.5{\cal}mm$) are predicted in the composite layers containing the metal-coated microspheres of low density (about 0.84 g/cc) for the electromagnetic radiation in microwave frequencies.

• Proceedings of the Korean Magnestics Society Conference
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• 2004.12a
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• pp.97-98
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• 2004

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.10a
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• pp.275-276
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• 2017