• 제목/요약/키워드: Colloidal systems

검색결과 7건 처리시간 0.08초

Confocal Microscopy of Colloidal Suspensions

  • Kim, Jin Young;Weon, Byung Mook
    • Applied Microscopy
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    • 제44권1호
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    • pp.30-33
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    • 2014
  • Colloidal systems or colloids consist of microparticles or nanoparticles (solute) uniformly suspended in a liquid (solvent), also called colloidal suspensions. They can mimic and exhibit microscopic or atomic aspects of molecular and atomic systems. They have been increasingly studied because of their similarity with atomic systems. They can be microscopically observed by optical microscopes because they are large enough in size and slow in motion to be monitored; microscopic methods are very useful and powerful in research on colloidal systems. Recently, confocal laser microscopy has been known as a powerful tool to obtain information of real-space and real-time behaviors of colloidal suspensions. In particular, it is possible to exactly track individual colloids in three dimensions with confocal microscopy. In this article, we briefly discuss the usefulness of confocal microscopy in colloidal systems that are currently used as model systems to resolve important questions in materials science.

Fundamentals of Particle Fouling in Membrane Processes

  • Bhattacharjee Subir;Hong Seungkwan
    • Korean Membrane Journal
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    • 제7권1호
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    • pp.1-18
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    • 2005
  • The permeate flux decline due to membrane fouling can be addressed using a variety of theoretical stand-points. Judicious selection of an appropriate theory is a key toward successful prediction of the permeate flux. The essential criterion f3r such a decision appears to be a detailed characterization of the feed solution and membrane properties. Modem theories are capable of accurately predicting several properties of colloidal systems that are important in membrane separation processes from fundamental information pertaining to the particle size, charge, and solution ionic strength. Based on such information, it is relatively straight-forward to determine the properties of the concentrated colloidal dispersion in a polarized layer or the cake layer properties. Incorporation of such information in the framework of the standard theories of membrane filtration, namely, the convective diffusion equation coupled with an appropriate permeate transport model, can lead to reasonably accurate prediction of the permeate flux due to colloidal fouling. The schematic of the essential approach has been delineated in Figure 5. The modern approaches based on appropriate cell models appear to predict the permeate flux behavior in crossflow membrane filtration processes quite accurately without invoking novel theoretical descriptions of particle back transport mechanisms or depending on adjust-able parameters. Such agreements have been observed for a wide range of particle size ranging from small proteins like BSA (diameter ${\~}$6 nm) to latex suspensions (diameter ${\~}1\;{\mu}m$). There we, however, several areas that need further exploration. Some of these include: 1) A clear mechanistic description of the cake formation mechanisms that clearly identifies the disorder to order transition point in different colloidal systems. 2) Determining the structure of a cake layer based on the interparticle and hydrodynamic interactions instead of assuming a fixed geometrical structure on the basis of cell models. 3) Performing well controlled experiments where the cake deposition mechanism can be observed for small colloidal particles (< $1\;{\mu}m$). 4) A clear mechanistic description of the critical operating conditions (for instance, critical pressure) which can minimize the propensity of colloidal membrane fluting. 5) Developing theoretical approaches to account for polydisperse systems that can render the models capable of handing realistic feed solutions typically encountered in diverse applications of membrane filtration.

A new versatile Microemulsion Gel Technology with flexible Viscosity

  • Ulrich Kux;Jorg Schreiber;Diec, Khiet-Hien;Sabine Ripke;Wittern, Klaus-Peter
    • 대한화장품학회:학술대회논문집
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    • 대한화장품학회 2003년도 IFSCC Conference Proceeding Book I
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    • pp.232-257
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    • 2003
  • It has been shown that transparent microemulsion gels of flexibly adjustable viscosity containing less than 10% w/w surfactants can be obtained just by cooling down through a new 1-step preparation procedure (via 4 different in-situ colloidal systems) using PIT-technology with a range of emulsifiers, co-emulsifiers and lipids. They can be used for a wide scope of applications. Specific examples have been given with antiperspirant formulas that proof the stability of these thickened microemulsions even with high content of electrolytes and low pH. We propose that the structure of these microemulsion gels can be described by cross-linking of nano-fine oil droplets via an ABA-triblock copolymer. A new generation of transparent antiperspirant roll-ons with significantly improved skin tolerance can now be formulated as an attractive alternative to alcohol-based products.

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마이크로 채널 내부 전기삼투 유속 측정을 통한 유리표면의 Zeta-potential 측정 (Zeta-potential Measurement on Glass Surface by Measuring Electro-osmotic Velocity inside a Micro-channel)

  • 한수동;이상준
    • 한국가시화정보학회:학술대회논문집
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    • 한국가시화정보학회 2005년도 추계학술대회 논문집
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    • pp.80-84
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    • 2005
  • Many important properties in colloidal systems are usually determined by surface charge ($\zeta$-potential) of the contacted solid surface. In this study, $\zeta$-potential of glass $\mu$-channel was evaluated from the electro-osmotic velocity distribution. The electro-osmotic velocity inside a glass $\mu$-channel was measured using a micro-PIV velocity field measurement technique. This evaluation method is more simple and easy to approach, compared with the traditional streaming potential technique. The $\zeta$-potential in the glass $\mu$-channel was measured for two different mole NaCl solutions. The effect of an anion surfactant, sodium dodecyl sulphate (SDS), on the electro-osmotic velocity and $\zeta$-potential in the glass surface was also studied. In the range of $0\∼6$mM, the surfactant SDS was added to NaCl solution in four different mole concentrations. As a result, the addition of SDS increases $\zeta$-potential in the surface of the glass $\mu$-channel. The measured $\zeta$-potential was found to vary from-260 to-70mV. When negatively charged particles were used, the flow direction was opposite compared with that of neutral particles. The $\zeta$-potential has a positive sign for the negative particles.

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Recent Progress in Drug Delivery Systems for Anticancer Agents

  • Kim, Chong-Kook;Lim, Soo-Jeong
    • Archives of Pharmacal Research
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    • 제25권3호
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    • pp.229-239
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    • 2002
  • Recent progress in understanding the molecular basis of cancer brought out new materials such as oligonucleotides, genes, peptides and proteins as a source of new anticancer agents. Due to their macromolecular properties, however, new strategies of delivery for them are required to achieve their full therapeutic efficacy in clinical setting. Development of improved dosage forms of currently marketed anticancer drugs can also enhance their therapeutic values. Currently developed delivery systems for anticancer agents include colloidal systems (liposomes, emulsions, nanoparticles and micelles), polymer implants and polymer conjugates. These delivery systems have been able to provide enhanced therapeutic activity and reduced toxicity of anticancer agents mainly by altering their pharmacokinetics and biodistribution. Furthermore, the identification of cell-specific receptor/antigens on cancer cells have brought the development of ligand- or antibody-bearing delivery systems which can be targeted to cancer cells by specific binding to receptors or antigens. They have exhibited specific and selective delivery of anticancer agents to cancer. As a consequence of extensive research, clinical development of anticancer agents utilizing various delivery systems is undergoing worldwide. New technologies and multidisciplinary expertise to develop advanced drug delivery systems, applicable to a wide range of anticancer agents, may eventually lead to an effective cancer therapy in the future.

마이크로 채널 내부 전기삼투 유동의 Zeta-potential 계측 (Measurement of Zeta-potential of Electro-osmotic Flow Inside a Micro-channel)

  • 한수동;이상준
    • 대한기계학회논문집B
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    • 제30권10호
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    • pp.935-941
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    • 2006
  • Many important properties in colloidal systems are usually determined by surface charge $({\zeta}-potential)$ of the contacted solid surface. In this study, ${\zeta}-potential$ of glass ${\mu}-channel$ was evaluated from the electro-osmotic velocity distribution. The electro-osmotic velocity inside a glass f-channel was measured using a micro-PIV velocity field measurement technique. This evaluation method is more simple and easy to approach, compared with the traditional streaming potential technique. The ${\zeta}-potential$ in the glass ${\mu}-channel$ was measured fur two different mole NaCl solutions. The effect of an anion surfactant, sodium dodecyl sulphate (SDS), on the electro-osmotic velocity and f-potential in the glass surface was also studied. In the range of $0{\sim}6mM$, the surfactant SDS was added to NaCl solution in few different mole concentrations. As a result, the addition of SDS increases ${\zeta}-potential$ in the surface of the glass ${\mu}-channel$. The measured $\zeta-potential$ was found to vary from -260 to -70mV. When negatively charged particles were used, the flow direction was opposite compared with that of neutral particles. The ${\zeta}-potential$ has a positive sign for the negative particles.

Nano-Bio 융합 연구를 위한 콜로이드 공학 (Colloidal Engineering for Nano-Bio Fusion Research)

  • 문준혁;이기라;이상엽;소재현;김영석;윤여균;조영상;양승만
    • Korean Chemical Engineering Research
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    • 제46권4호
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    • pp.647-659
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    • 2008
  • 콜로이드는 거시적으로 균일한 성질을 갖는 입자분산계이다. 콜로이드 입자는 다양한 입자분산계의 모델로서 많은 기초연구가 이루어져 왔을 뿐만 아니라, 산업적으로 다양하게 응용이 되었다. 최근에는 나노-바이오 관련 연구에 적용되어 새롭게 각광을 받고 있는 나노 소재중 하나이다. 본 총설에서는 입자 분산계의 정의 및 분류에 대해 간략히 기술하고, 나노-바이오 응용을 위한 표면 성질 및 표면 개질방법에 대해 다룰 것이다. 또한, 기존의 구형의 입자분산계에서 더 나아가, 모양과 크기가 제어된 입자 분산계의 합성에 관한 최근 결과를 소개하였다. 마지막으로, 콜로이드 입자의 나노-바이오 응용분야로서, 금속 콜로이드 잉크와, 3차원 콜로이드 결정을 활용한 나노-바이오 센서, 및 2차원 콜로이드 구조를 이용한 패턴제작과 응용 연구에 대해 살펴보았다.