Detection of Subtle Environmental Changes by Structural Colors of Soft Colloidal Nanoparticle Films

Tae Soup Shim(심태섭) 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1

Structural colors of a self-assembled colloidal particles and a thin polymer film have long been studied for engineering stimuli-responsive colorimetric sensors. Because structural color of colloidal structure is determined by various parameters such as refractive index, lattice spacing, and angle of incident light, a flexible-, and soft colloidal structure is promising tools for designing stimuli-responsive colorimetric sensors. Here, I introduce two examples of structural color sensors made of self-assembled colloidal structures that response chemical and physical stimulus. By introducing thin colloidal crystal membrane and high refractive index dopamelanin nanoparticles film, subtle changes of physical and chemical stimulus can be detected, respectively. Such strategy can offer preparation of sensitive, cost-effective and energy-efficient colorimetric sensors that can be applied to miniaturized devices and disposable chemical indicators.

Shape changing thin films powered by DNA hybridization

Shim, Tae Soup,Estephan, Zaki G.,Qian, Zhaoxia,Prosser, Jacob H.,Lee, Su Yeon,Chenoweth, David M.,Lee, Daeyeon,Park, So-Jung,Crocker, John C. Nature Publishing Group, a division of Macmillan P 2017 Nature nanotechnology Vol.12 No.1

<P>Active materials that respond to physical(1-3) and chemical(4-6) stimuli can be used to build dynamic micromachines that lie at the interface between biological systems and engineered devices(7,8). In principle, the specific hybridization of DNA can be used to form a library of independent, chemically driven actuators for use in such microrobotic applications and could lead to device capabilities that are not possible with polymer- or metal-layer-based approaches. Here, we report shape changing films(9) that are powered by DNA strand exchange reactions with two different domains that can respond to distinct chemical signals. The films are formed from DNA-grafted gold nanoparticles(10,11) using a layer-by-layer deposition process. Films consisting of an active and a passive layer show rapid, reversible curling in response to stimulus DNA strands added to solution. Films consisting of two independently addressable active layers display a complex suite of repeatable transformations, involving eight mechanochemical states and incorporating self-righting behaviour.</P>

Dynamic Modulation of Photonic Bandgaps in Crystalline Colloidal Arrays Under Electric Field

Shim, Tae Soup,Kim, Shin‐,Hyun,Sim, Jae Young,Lim, Jong‐,Min,Yang, Seung‐,Man WILEY‐VCH Verlag 2010 Advanced Materials Vol.22 No.40

<P><B>Dynamic modulation of photonic bandgaps</B> in crystalline colloidal arrays is achieved by application of electric field. Highly charged polystyrene particles spontaneously create the crystal lattice, which is compressed or relaxed under external electric field by electrokinetic force. As a result, structural color of colloidal crystals as a photonic bandgap can be tuned or fixed with unprecedentedly fast and precise manner. </P>

Stimuli-Responsive Self-Folding of Polymeric Bilayers toward Programmable Microactuator

Tae Soup Shim,Daeyeon Lee,So-Jung Park,John C. Crocker 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

Lateral particle migration in shear-thinning colloidal dispersion

Kim Young Hwan,Shim Tae Soup,Kim Ju Min 한국유변학회 2022 Korea-Australia rheology journal Vol.34 No.4

Colloidal dispersions have been frequently encountered in a wide range of industrial applications, such as foods, paints, and Li-ion electrode slurries. Therefore, it is essential to understand the rheological and flow characteristics of colloidal dispersions to improve the quality and optimize the processing conditions of colloidal products. The shear viscosity of a colloidal dispersion deviates from Newtonian behavior, exhibiting shear thinning and/or shear thickening as the volume fraction of the colloidal particles increases. However, there are not many reports on the non-Newtonian flow phenomena caused by the normal stress differences of colloidal dispersion due to their small magnitude. Recently, these normal stress differences in colloidal dispersions with a constant shear viscosity lead to a single-line focused streams of micron-sized particles along the centerline of microchannels. In this study, the lateral migration of single micron-sized particles suspended in poly (N-isopropylacrylamide) microgel dispersions with a shear-thinning viscosity was investigated. The micron-sized particles migrated toward the centerline or between the centerline and wall of a microchannel depending on the volume fraction of the colloidal particles and the flow conditions. The current findings are expected to contribute to our understanding of the non-Newtonian fluid dynamics in colloidal dispersions and flow-induced particle segregation phenomenon.

거대분자체 자기조립 및 응용

이승우(Seungwoo Lee),심태섭(Tae Soup Shim) 한국고분자학회 2019 고분자 과학과 기술 Vol.30 No.2

Droplet Microfluidics for Producing Functional Microparticles

Kim, Ju Hyeon,Jeon, Tae Yoon,Choi, Tae Min,Shim, Tae Soup,Kim, Shin-Hyun,Yang, Seung-Man American Chemical Society 2014 Langmuir Vol.30 No.6

<P>Isotropic microparticles prepared from a suspension that undergoes polymerization have long been used for a variety of applications. Bulk emulsification procedures produce polydisperse emulsion droplets that are transformed into spherical microparticles through chemical or physical consolidation. Recent advances in droplet microfluidics have enabled the production of monodisperse emulsions that yield highly uniform microparticles, albeit only on a drop-by-drop basis. In addition, microfluidic devices have provided a variety of means for particle functionalization through shaping, compartmentalizing, and microstructuring. These functionalized particles have significant potential for practical applications as a new class of colloidal materials. This feature article describes the current state of the art in the microfluidic-based synthesis of monodisperse functional microparticles. The three main sections of this feature article discuss the formation of isotropic microparticles, engineered microparticles, and hybrid microparticles. The complexities of the shape, compartment, and microstructure of these microparticles increase systematically from the isotropic to the hybrid types. Each section discusses the key idea underlying the design of the particles, their functionalities, and their applications. Finally, we outline the current limitations and future perspectives on microfluidic techniques used to produce microparticles.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2014/langd5.2014.30.issue-6/la403220p/production/images/medium/la-2013-03220p_0013.gif'></P>

Regenerative Astaxanthin Extraction from a Single Microalgal (<i>Haematococcus pluvialis</i>) Cell Using a Gold Nano-Scalpel

Praveenkumar, Ramasamy,Gwak, Raekeun,Kang, Mijeong,Shim, Tae Soup,Cho, Soojeong,Lee, Jiye,Oh, You-Kwan,Lee, Kyubock,Kim, Bongsoo American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.40

<P>Milking of microalgae, the process of reusing the biomass for continuous production of target compounds, can strikingly overcome the time and cost constraints associated with biorefinery. This process can significantly improve production efficiency of highly valuable chemicals, for example, astaxanthin (AXT) from <I>Haematococcus pluvialis</I>. Detailed understanding of the biological process of cell survival and AXT reaccumulation after extraction would be of great help for successful milking. Here we report extraction of AXT from a single cell of <I>H. pluvialis</I> through incision of the cell wall by a gold nanoscalpel (Au-NS), which allows single-cell analysis of wound healing and reaccumulation of AXT. Interestingly, upon the Au-NS incision, the cell could reaccumulate AXT at a rate two times faster than the control cells. Efficient extraction as well as minimal cellular damage, keeping cells alive, could be achieved with the optimized shape and dimensions of Au-NS: a well-defined sharp tip, thickness under 300 nm, and 1–3 μm of width. The demonstration of regenerative extraction of AXT at a single cell level hints toward the potential of a milking process for continuous recovery of target compounds from microalgae while keeping the cells alive.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-40/acsami.5b07651/production/images/medium/am-2015-07651u_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5b07651'>ACS Electronic Supporting Info</A></P>

Inertio-elastic flow instabilities in a 90° bent microchannel

Kim, Junghee,Hong, Sun Ok,Shim, Tae Soup,Kim, Ju Min The Royal Society of Chemistry 2017 SOFT MATTER Vol.13 No.34

<▼1><▼1><P>We report the novel inertio-elastic flow instability in dilute polymer solutions for a microchannel having a 90° bent geometry.</P></▼1><▼2><P>Biological samples having viscoelastic properties are frequently tested using microfluidic devices. In addition, viscoelastic fluids such as polymer solutions have been used as a suspending medium to spatially focus particles in microchannels. The occurrence of flow instability even at low Reynolds number is a unique property of viscoelastic fluids. In this study, we report the instability in viscoelastic flow for a channel having a 90° bent geometry, which is a characteristic of many microfluidic devices. Interestingly, we observed that the flow instability in aqueous poly(ethylene oxide) (PEO) solution occurs when the concentration of PEO is as low as 50 ppm. We systematically investigated the effects of the polymer concentration, flow rate, and elasticity number on the flow instability. The results show that the flow is stabilized in shear-thinning fluids, whereas the flow instability is amplified when both elastic and inertial effects are pronounced. We believe that this study is useful to design microfluidic devices such as cell-deformability measurement devices based on viscoelastic particle focusing.</P></▼2></▼1>

Hydrogel micropost-based qPCR for multiplex detection of miRNAs associated with Alzheimer's disease

Choi, Woongsun,Yeom, Sang Yun,Kim, Junsun,Jung, Seungwon,Jung, Seungho,Shim, Tae Soup,Kim, Sang Kyung,Kang, Ji Yoon,Lee, Soo Hyun,Cho, Il-Joo,Choi, Jungkyu,Choi, Nakwon Elsevier Applied Science 2018 Biosensors & bioelectronics Vol. No.

<P><B>Abstract</B></P> <P>Quantitative polymerase chain reaction (qPCR) renders profiling of genes of interest less time-consuming and cost-effective. Recently, multiplex profiling of miRNAs has enabled identifying or investigating predominant miRNAs for various diseases such as cancers and neurodegenerative diseases. Conventional multiplex qPCR technologies mostly use colorimetric measurements in solution phase, yet not only suffer from limited multiplexing capacity but also require target-screening processes due to non-specific binding between targets and primers. Here, we present hydrogel micropost-based qPCR for multiplex detection of miRNAs associated with Alzheimer's disease (AD). Our methodology promises two key advantages compared with the conventional solution-based PCR: 1) nearly no non-specific crosstalks between targets and primers, and 2) practically valuable multiplexing by spatial encoding within a single microchamber. Specifically, we immobilized hydrogel microposts (~ 400µm in diameter) within commercially available polycarbonate PCR chips by multi-step ultraviolet (UV, 365nm) exposure. We optimized this photoimmobilization for thermal cycles of PCR as well. Acrylated forward primers incorporated in polyethylene glycol diacrylate (PEGDA) posts played a crucial role to confine fluorescent signal of cDNA amplification within the PEGDA hydrogel. To demonstrate the potential of our platform, we successfully verified multiplex detection of five miRNAs, which were reported to be highly correlated with AD, from a complex buffer of human plasma.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrogel micropost-based multiplex qPCR is reported for detection of miRNAs. </LI> <LI> Multi-step UV-exposure allows for immobilization of PEGDA microposts in PCR chips. </LI> <LI> Hydrogel-based qPCR results in the significant elimination of non-specific binding. </LI> <LI> 5-plex detection of miRNAs is presented with excellent specificity & selectivity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>