• Archives of Pharmacal Research
• /
• 제9권3호
• /
• pp.145-152
• /
• 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
• /
• 제17권1호
• /
• pp.98-103
• /
• 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
• /
• 제16권4호
• /
• pp.312-317
• /
• 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
• /
• 제13권11호
• /
• pp.1850128.1-1850128.10
• /
• 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.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1993년도 춘계학술대회
• /
• pp.7-14
• /
• 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
• /
• 제49권1호
• /
• pp.172-177
• /
• 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.

• 한국자기학회지
• /
• 제16권4호
• /
• pp.221-227
• /
• 2006

균일한 마그나타이트 나노 입자를 합성하기 위해 음향화학법을 이용한 공침 기술을 적용해 합성 하였다. 입자의 크기를 제어하고 응집을 막기 위해 계면활성제로 올레인산을 사용하였다. 이 방법으로 합성한 마그네타이트 나노입자를 의학적으로 이용하기 위해 나노 입자의 표면을 개질하고 자성 미소구체를 제조 하였다. 마그네타이트 입자의 표면 개질과 자성 미소 구체를 제조하기 위해 저독성, 생분해성, 생체 친화성의 특징을 갖고 있는 키토산과 $\beta$-글루칸을 사용하였다. 생체 고분자로 마그네타이트 나노 입자를 피복하기 위해 묽은 초산 용액을 이용하여 키토산을 용해하고 $\beta$-글루칸은 묽은 수산화나트륨에 용해하여 사용 하였다.나노 입자의 피복은 자성유체를 초음파를 가해주면서 용해시킨 각각의 생체 고분자 용액을 서서히 가하여 나노 입자를 피복하였다. 자성 미소구체는 2 % 키토산과 5 %의 $\beta$-글루칸 수용액을 이용해 제조 하였다. 마그네타이트를 생체 고분자에 분산 시켜 주기 위해 콜로이드 상으로 제조 하고 초음파를 조사 해주어 분무 장치를 통해 미소 구체를 제조하였다. SQUID(SuperconductingQuantum Interference Device)를 측정한 결과 피복한 나노 입자와 미소구체에서 모두 초상자성을 나타내고 있었으며 MRI(Magnetic Resonance Imaging) 측정 결과 MRI 조영제와 색전 물질로서 사용하기 적합 하다는 것을 확인 할 수 있었다.

• 한국자기학회지
• /
• 제15권2호
• /
• pp.67-75
• /
• 2005

경량 전파흡수체 구현 방안의 하나로 저밀도(약 0.2g/cc) 중공미세구 표면에 수 ${\cal}um$ 두께의 Co 피막을 무전해 도금에 의해 코팅하고, 고주파 전자기 특성 및 전파흡수특성을 조사하였다. Co 도금은 활성화 처리와 도금공정 2단계 과정을 거쳐 시행되었다. 도금공정의 반복에 의해 두께 $2{\~}3\mu$m의 균일한 Co 피막을 얻을 수 있었다. 이 분말을 실리콘 고무와 혼합하여 복합체를 제조하고, 고주파 전자기 물성 및 전파흡수특성을 회로망 분석기로 측정하였다. Co 피막의 강자성 특성 및 전도 특성에 의해 높은 자기손실 및 유전상수를 얻을 수 있었다. 이와 같은 전자기적 특성에 의해 GHz 대역에서 우수한 전파흡수특성(두께 2.0$\~$2.5mm, 전파흡수능 20dB 이상)이 확인되었다. 특히 Co 도금 중공미세구의 밀도(0.84 g/cc)는 페라이트(5.0 g/cc)에 비해 약 1/6에 불과하기 때문에 경량 전파흡수체로서 응용가치가 매우 높음을 제시할 수 있었다.

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2004년도 동계학술연구발표회 논문개요집
• /
• pp.97-98
• /
• 2004

• 한국방사성폐기물학회:학술대회논문집
• /
• 한국방사성폐기물학회 2017년도 추계학술논문요약집
• /
• pp.275-276
• /
• 2017