• 한국세라믹학회지
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• 제49권6호
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• pp.518-522
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• 2012

Hyaluronic acid (HA) microbeads were synthesized by dropping 0.5 wt% of sodium hyaluronate dissolved in NaOH into 0.2 vol% of divinyl sulfone dissolved in 2-methyl-1propanol at a speed of 0.005 ml/min. HA microbeads were collected from a divinyl sulfone crosslinker solution stirred at 200 to 400 rpm for 5 h at temperatures from room temperature to $60^{\circ}C$ at intervals of $10^{\circ}C$. The crosslinked microbeads were then cleaned thoroughly using distilled water and ethanol. SEM results revealed that the microbeads were white-colored spheres. The 3-D porous network structure of the microbeads became dense with an increase in the crosslinking temperature; however, no dependence of the crosslinking temperature on the microbead size was detected. The extent of swelling decreased from 970% to 670% with an increase in the crosslinking temperature from room temperature to $60^{\circ}C$, most likely due to the increase in the degree of crosslinking.

• 한국세라믹학회지
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• 제43권8호
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• pp.458-462
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• 2006

A simple pressing process using a SiC powder, $Al_2O_3-Y_2O_3$ sintering additive, and polymer microbeads for fabricating cellular SiC ceramics is demonstrated. The strategy for making the cellular ceramics involves: (i) forming certain shapes using a mixture of a SiC powder, $Al_2O_3-Y_2O_3$ sintering additive, and polymer microbeads by pressing; (ii) heat-treatment of the formed body to burn-out the microbeads; and (iii) sintering the body. By controlling the microsphere content and sintering temperature, it was possible to adjust the porosity in a range of 16% to 69%. The flexural and compressive strengths of cellular SiC ceramics with $\sim$40% porosity were $\sim$60 MPa and $\sim$160 MPa, respectively.

• 대한화장품학회지
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• 제30권3호
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• pp.399-404
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• 2004

새로운 Gly-His-Lys (약자로 GHK)가 결합된 키토산을 $N^{\alpha}-Fmoc$ 아미노산과 BOP 커플링 시약을 사용한 고상법에 의해 제조하였다. 이를 위해 키토산 마이크로 비드를 W/O 에멀젼 상분리법으로 평균 입자크기 70 마이크로미터로 얻었다. GHK 펩타이드는 순차적으로 고상법에 의해 키토산 마이크로비드 위에 커플링 하였다. 아미노산 분석을 실시한 결과 Gly, His, kys의 비율이 1.02:1.13:0.96의 비율로 나타나 이론치와 거의 일치함을 확인할 수 있었다. GHK 펩타이드가 결합된 마이크로비드의 세포증식 효과는 MTT 분석으로 측정하였다. 측정결과 GHK 펩타이드가 결합된 키토산 마이크로비드는 대조군인 펩타이드가 결합되지 않은 키토산 마이크로비드 자체에 비해 높은 세포증식 효과를 보였다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVI)
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• pp.19-19
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• 2005

This paper reports a novel magnetic force-based microfluidic immunoassay using microbeads and magnetic nanoparticles. The magnetic force-based immunoassay was devised first and successfully applied to detect the rabbit IgG as the model analyte of microfluidic sandwich immunoassay. The microchannels were fabricated by poly(dimethysiloxane) (PDMS) molding processes and bonded on a slide glass by plasma treatment. At the part of the inlet, sample solution was hydrodynamically focused. The focused microbeads of sample solution were flowed through the 150 ${\mu}m$ width channel of outlet. However, when the microbeads are conjugated with the superparamagnetic nanoparticles under the applied magnetic fields, they will switch their flow path and flow through the 95 ${\mu}m$ width channel of outlet. The movements of microbeads conjugated with magnetic nanoparticles were demonstrated by magnetic field $gradients.^{1)}$ High magnetic field gradients using micro electromagnets could be applied to this detection method for high sensitivity and lower detection limit. In addition, the multiplexed $immunoassay^{2)}$ using an encoded microbead which is immobilized with a certain antibody could be possible using this detection principle.

• 센서학회지
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• 제13권5호
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• pp.378-382
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• 2004

A micromachined fluidic structure for the introduction of liquid samples into a chip-based sensor array composed of individually addressable polymeric microbeads has been developed. The structure consists of a separately attached cover glass, a single silicon chip having micromachined channels and microbead storage cavities, and a glass carver. In our sensor array, transduction occurs via colorimetric and fluorescence changes to receptors and indicator molecules that are covalently attached to termination sites on the polymeric microbeads. Data streams are acquired for each of the individual microbeads using a CCD. One of the key parts of the structure is a passive fluid introduction system driven only by capillary force. The velocity of penetration of a horizontal capillary for the device having a rectangular cross section has been derived, and it is quite similar to the Washburn Equation calculated for a pipe with a circular cross section having uniform radius. The test results show that this system is useful in a ${\mu}$-TAS and biomedical applications.

• 대한화장품학회지
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• 제21권2호
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• pp.49-56
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• 1995

키토산 마이크로캡슐 및 마이크로비드를 W/O emulsion법에 의해 제조하였으며, SEM을 통해 이들의 morphology를 관찰하였다. 마이크로캡슐은 SEM을 통해 관찰한 결과 약 8$mu extrm{m}$ 정도의 표피층을 가지고 있었으며, 평균 입자의 크기는 약 250$\mu\textrm{m}$ 이였다. 마이크로캡슐의 팽윤부피를 측정한 결과 양성자성 용매가 비양성자성 용매에 비해 상대적으로 높은 팽윤성을 보였다. 또한 메칠바이올렛을 함유시킨 후 그 방출거동을 pH 변화 및 라이소자임 첨가에 따라 관찰한 결과, pH 5.1에서 라이소자임 첨가시 방출속도가 높게 나타났다. 한편 W/O emulsion법에 의해 제조한 마이크로비드의 경우 70$\mu\textrm{m}$정도의 크기를 보였으며 다공성의 표면구조를 나타내었다. 용매 종류별 팽윤성을 측정한 결과 수용액에서 마이크로캡슐에 비해 2배 이상의 팽윤부피를 나타내었다.

• 한국가시화정보학회지
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• 제14권3호
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• pp.38-45
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• 2016

Separation of particles based on different sizes, detection of pathogenic bacteria and isolation of leukocytes from whole blood are typical applications of spiral or helical microchannels. The present study focuses on developing a CD4+ T-cell counting device for monitoring HIV/AIDS patients with the aid of a helical minichannel used for a sample cartridge. For the experiment, $10{\mu}m$ sized microbeads were used for visualization with a fluorescence imaging system. Alignment of microbeads was investigated in a stationary and spinning sample cartridge filled with glycerol-water mixtures of different densities. The helical minichannel was spun using a DC motor controlled by an Arduino board with a Bluetooth shield. It was found that when the sample cartridge was made stationary, no bead alignment was achieved for a medium with density (0% and 20% glycerol) lower than that of the beads, but when it was spun at 2000-3000 rpm for 1-4 min, an alignment was obtained at the top of the channel facilitating optical detection and enumeration of those microbeads. Since an alignment of microbeads was achieved for a medium with density as that of blood plasma, the same approach can be applied for aligning and counting CD4+ T-lymphocytes in whole blood samples collected from patients.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권6호
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• pp.503-509
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• 2006

Molecularly imprinted polymeric microbeads (MIPMs) were prepared by the suspension and modified suspension polymerization methods using D-phenylalanine as the template, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, toluene as the porogen, polyvinyl alcohol as the stabilizer, and sodium dodecyl sulfate as the surfactant. The addition of a surfactant to the conventional suspension polymerization mixture decreased the mean particle size of the MIPMs and increased the adsorption selectivity. For the modified suspension polymerization method, the mean particle size of the MIPMs was smaller than the particle size of MIPMs prepared via conventional suspension polymerization. Moreover, the adsorption selectivity improved considerably compared to the adsorption selectivities of MIPs reported previously.

• Bulletin of the Korean Chemical Society
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• 제27권1호
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• pp.37-38
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• 2006

• Journal of Microbiology and Biotechnology
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• 제25권12호
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• pp.2058-2071
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• 2015

A comparative study was conducted to evaluate precision and accuracy in controlling the temperature dependence of encapsulated microbial time-temperature integrators (TTIs) developed using two different emulsification techniques. Weissela cibaria CIFP 009 cells, immobilized within 2% Na-alginate gel microbeads using homogenization (5,000, 7,000, and 10,000 rpm) and Shirasu porous glass (SPG) membrane technologies (10 μm), were applied to microbial TTIs. The prepared micobeads were characterized with respect to their size, size distribution, shape and morphology, entrapment efficiency, and bead production yield. Additionally, fermentation process parameters including growth rate were investigated. The TTI responses (changes in pH and titratable acidity (TA)) were evaluated as a function of temperature (20℃, 25℃, and 30℃). In comparison with conventional methods, SPG membrane technology was able not only to produce highly uniform, small-sized beads with the narrowest size distribution, but also the bead production yield was found to be nearly 3.0 to 4.5 times higher. However, among the TTIs produced using the homogenization technique, poor linearity (R²) in terms of TA was observed for the 5,000 and 7,000 rpm treatments. Consequently, microbeads produced by the SPG membrane and by homogenization at 10,000 rpm were selected for adjusting the temperature dependence. The E_a values of TTIs containing 0.5, 1.0, and 1.5 g microbeads, prepared by SPG membrane and conventional methods, were estimated to be 86.0, 83.5, and 76.6 kJ/mol, and 85.5, 73.5, and 62.2 kJ/mol, respectively. Therefore, microbial TTIs developed using SPG membrane technology are much more efficient in controlling temperature dependence.