Earticle

본 연구는 피부청결 화장품에 첨가된 미세플라스틱의 미세구조와 형태적 특성을 주사전자현미경(scanning electron microscope)으로 관찰 분석하였다. 미세플라스틱의 크기는 직경이 250㎛에서부터 1.5㎜까지 아주 다양한 크기 로 존재하였다. 비교적 작은 미세플라스틱은 길쭉한 입자 모양을 하고 있었고 커다란 미세플라스틱은 입방형의 형태를 하 고 있었다. 입방형의 미세플라스틱은 대부분 정사면체나 직사면체의 형태로 관찰되었다. 입방형 미세플라스틱의 표면은 돌출된 부위 없이 매끄럽게 관찰되었지만 불규칙하게 많은 틈이 형성되어 있었다. 벌어진 틈의 간격은 약 5㎛에서부터 20㎛ 까지 측정되었다. 이들 틈은 미세플라스틱의 표면에서부터 내부 까지 형성되어 있는지는 확인되지 않았다.

We investigated the microstructure and morphological characteristics of microplastics added to rinse off cosmetics by scanning electron microscope. The size of the microplastic was in a wide range of sizes, from 250㎛ to 1.5㎜ in diameter. The small microplastics were in the shape of elongated particles and the large microplastics were cuboidal. Most cubic microplastics were observed in the form of squares or rectangles. The surface of the cubic microplastic was smoothly observed without protruding portions, but irregularly many gaps were formed. The gap between openings was measured from about 5㎛ to 20㎛. It has not been confirmed that these gaps are formed from the surface of the microplastic to the inside there of.

본 연구는 스크럽 화장품을 사용하여 피부상태의 변화를 피부분석장비로 분석하고 마이크로비드의 형태적 특징을 더마스코프와 주사전자현미경으로 관찰하였다. 더마스코프 관찰에서 클렌징을 하는 과정 중의 얼굴피부에 붙어있는 마이 크로비드는 서로 밀착되어 존재하고 있거나 분산되어 있었다. 클렌징 한 피부는 깨끗하고 매끄럽게 관찰되었으며 표피 각 질세포들 사이의 미세한 주름이 줄어든 것을 확인하였다. 주사전자현미경 관찰에서 구슬모양의 마이크로비드 표면은 심한 굴곡이나 거친 표면을 가지고 있지 않았다. 스크럽을 하기 전과 후의 유분, 수분, pH의 변화를 비교분석한 결과 스크럽을 하기전의 피부가 스크럽 후의 피부보다 수분과 유분의 함량이 높게 나타났고 pH의 변화는 큰 차이가 없었다.

In this study, the change of skin condition was analyzed by skin analysis equipment using scrub cosmetics, and the morphological characteristics of microbead were observed by dermascope and scanning electron microscope. In the dermascope observation, during the process of cleansing, the microbeads attached to the skin existed in close contact with each other or dispersed. The skin after scrubbing was clean and smooth and the fine wrinkles between epidermal keratinocytes were reduced. In the scanning electron microscopic observation, the microbead surface did not have severe bending or rough surface. The skin moisture and oil content were higher than the scrub skin before the scrub, and there was no significant difference in the pH.

We develop a micro analysis and detection system for replicase of the hepatitis C virus. The fabricated analysis system consists of a bead based microchip and a computer based controller. A microheater, a micro temperature sensor and a microreator for bead packing is integrated in one microchip to realize several sequences for the capture and the elution of replicase. In this study, we used the PEG-grafted PS bead on which RNA aptamers are immobilized and performed thermal denaturation for releasing target molecules, and analyzed by MALDI-TOF MS. We performed several experiments to optimize conditions. As a result, we could acquire several matched peaks (26 % sequence coverage) of HCV replicase using the following condition: at room temperature for 20 min of binding time and at 85℃ for 30s of thermal denaturation time.

Au nanoparticles (AuNPs) have been widely used not only as optical labels or ‘weight” labels for the detections of biorecognition events but also an amplifier of surface plasmon resonance biosensors. The intrinsic property of gold nuclei composing of a group of Au atoms to catalyze the reduction of metal ions on the NPs and thereby to enlarge the metallic nanoparticles is employed in different biosensing paths. In a solution containing Au+ ions (e.g. HAuCl4) and the Au clusters, hydrated electrons which are reduced from oxidation of reducers (H2O2, sodium citrate, ascorbic acid, or NaBH4) will be used to reduce the Au+ ion leading to the deposition of Au+ to the Au0 (Au clusters). The reaction will be catalyzed continuously by the Au0 until the Au+ ions and hydrated electrons are exhausted. As a result, the AuNPs will be grown and their optical properties are also changed. If the AuNP nanoclusters are used as probes, the color change will be dependent on amount of analytes, thus give a quantitative monitoring of the analytes. In this study, we incorporate the use of magnetic beads with the nanocrystalline growth to quantify a target protein based on immunoreactions. Prostate specific antigen (PSA) is chosen as the target analyte because of its values in diagnosis of prostate cancer. A double-sandwiched immunoassay is performed by gold-tagged monoclonal PSA antibody-PSA antigen – magnetic bead-tagged polyclonal PSA antibody interactions. After the immunoreactions, the target analytes are preconcentrated and separated by the magnetic beads while the nanogrowth plays a role of colorimetric signal developer. The result shows that this is a very sensitive, robust and excellent strategy to detect biological interactions. PSA antigen is detected at femtomolar level with very high specificity under the presence of undesired proteins of crude samples. Furthermore, the method also shows great potential to detect other biological interactions. More details will be described in our presentation.

This study aims to provide microstructural characterization for the matrix graphite which molten salt reactors (MSRs) use, and improve resistance to molten salt infiltration of the matrix graphite for fuel elements. Mesocarbon microbeads (MCMB) densified matrix graphite A3-3 (MDG) was prepared by a quasi-isostatic pressure process. After densification by MCMBs with average particle sizes of 2, 10, and 16 ㎛, the pore diameter of A3-3 decreased from 924 nm to 484 nm, 532 nm, and 778 nm, respectively. Through scanning electron microscopy, the cross-section energy spectrum and time-of-flight secondary ion mass spectrometry, resistance levels of the matrix graphite to molten salt infiltration were analyzed. The results demonstrate that adding a certain proportion of MCMB powders can improve the anti-infiltration ability of A3-3. Meanwhile, the closer the particle size of MCMB is to the pore diameter of A3-3, the smaller the average pore diameter of MDG and the greater the densification. As a matrix graphite of fuel elements in MSR was involved, the thermal and mechanical properties of matrix graphite MDG were also studied. When densified by the MCMB matrix graphite, MDGs can meet the molten salt anti-infiltration requirements for MSR operation.

The Planar Hall effect in a spin valve structure has been applied as a biosensor being capable of detecting $Dynabeads^{(R)}$ M-280. The sensor performance was tested under the application of a DC magnetic field where the output signals were obtained from a nanovoltmeter. The sensor with the pattern size of $50{\times}100{\mu}m^2$ has produced high sensitivity; especially, the real-time profiles by using that sensor revealed significant performance at external applied magnetic field of around 7.0 Oe with the resolution of 0.04 beads per $\mu m^2$. Finally, a successful array including 24 patterns with the single sensor size of $3{\times}3{\mu}m^2$ has shown the uniform and stable signals for single magnetic bead detection. The comparison of this sensor signal with the others has proved feasibility for biosensor application. This, connecting with the advantages of more stable and high signal to noise of PHR sensor's behaviors, can be used to detect the biomolecules and provide a vehicle for detection and study of other molecular interaction.

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.

Chitosan microcapsules and microbeads were prepared by W/O emulsion method, and their morphologies were observed through SEM. The microcapsules have skin layer of 8 Um and 250 Um of mean diameter, The swelling test showed higher s welling ability in protic solvents than in aphotic solvents. After containing moth-yl violet in the microcapsules, the release patterns were investigated. The results sho wed that the addition of Iysozyme in pH 5.1 acetate buffer accelerated the re-lease rate. In case of the microbeads, the mean diameter was about 70 Um. The surface of the microbeads showed porous structures. The swelling ability of the beads revealed two times higher than the one of the microcapsules.

This paper describes a micro total analysis system ($\mu$ TAS) for detecting and digesting the target protein which includes a bead based temperature controllable microchip and computer based controllers for temperature and valve actuation. We firstly combined the temperature control function with a bead based microchip and realized the on-chip sequential reactions using two kinds of beads. The PEG-grafted bead, on which RNA aptamer was immobilized, was used for capturing and releasing the target protein. The target protein can be chosen by the type of RNA aptamer. In this paper, we used the RNA aptamer of HCV replicase. The trypsin coated bead was used for digesting the released protein prior to the matrix assisted laser desorption ionization time of flight mass spectrometer (MALDI TOF MS). Heat is applied for release of the captured protein binding on the bead, thermal denaturation and trypsin digestion. PDMS microchannel and PDMS micro pneumatic valves were also combined for the small volume liquid handling. The entire procedures for the detection and the digestion of the target protein were successfully carried out on a microchip without any other chemical treatment or off-chip handling using $20\;{\mu}l$ protein mixture within 20 min. We could acquire six matched peaks (7% sequence coverage) of HCV replicase.