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Advanced encapsulation of active ingredients via multiple emulsions
최창형 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
We present multiple layered emulsion drops with an ultra-thin intermediate layer in a single step microfluidic emulsification, to achieve high encapsulation efficiency and retention of small actives. Using a capillary microfluidic device, we produce monodisperse triple emulsion drops, enveloping an ultra-thin water layer in between the encapsulant and the photocurable oil, which transforms into a polymeric shell upon UV illumination. We demonstrate that the ultra-thin water layer can be tuned by adding hydrogel precursor; the polymerized hydrogel shell provides a physical barrier that separates the hydrophobic cargo from directly contacting the polymer shell. This hydrogel shell enables enhanced retention of highly volatile small organic compound (fragrance) that are known to be very challenging. In addition, by utilizing the omniphobic fluorocarbon oil as the ultra-thin intermediate layer, we encapsulate a broad range of polar and non-polar cargoes in a single platform.
최창형,이지혜,황택성,이창수,김윤곤,양영헌,허강무 한국고분자학회 2010 Macromolecular Research Vol.18 No.3
This study reports a simple but efficient method for create bacteria microarrays on a predesigned functional surface consisting of two distinctive regions; a bacterial immobilizing area and a nonimmobilizing region. The functionalized surface was fabricated by a combination of self-assembled polyelectrolyte multilayers (PEL) and micromolding in the capillaries (MIMIC) of poly(ethylene glycol)-poly(D,L-lactide) diblock copolymer (PEGPLA). The PEL region provides bacterial immobilization, and the nonspecific binding of bacteria was prevented using PEG-PLA as passivation molecules. The topological change in the functionalized surface was characterized by atomic force microscopy (AFM), which suggested the occurrence of a laterally homogeneous and well defined surface modification. An analysis of the fluorescence signals from the bacteria microarray indicates that the bacteria are viable and grow after immobilization on patterned surface features. The rapid fabrication of two different functionalities on the surface results in a uniform bacteria pattern with a high signal to noise ratio and shape flexibility,such as lines, squares, and circles. Moreover, the pattern size could be controlled from 20 to 100 μm.
In Situ Microfluidic Synthesis of Monodisperse PEG Microspheres
최창형,정재훈,황택성,이창수 한국고분자학회 2009 Macromolecular Research Vol.17 No.3
This study presents a microfluidic method for the production of monodisperse poly(ethylene glycol) (PEG) microspheres using continuous droplet formation and in situ photopolymerization in microfluidic devices. We investigated the flow patterns for the stable formation of droplets using capillary number and the flow rate of the hexadecane phase. Under the stable region, the resulting microspheres showed narrow size distribution having a coefficient of variation (CV) of below 1.8%. The size of microspheres (45~95 μm) could be easily controlled by changing the interfacial tension between the two immiscible phases and the flow rates of the dispersed or continuous phase.
Microfluidic Synthesis of Anisotropic Particles from Janus Drop by in situ Photopolymerization
최창형,이창수,Sora Hwang,정재민,강성민,Jongmin Kim 대한의용생체공학회 2012 Biomedical Engineering Letters (BMEL) Vol.2 No.2
Purpose This study presents a microfluidic method to generate anisotropic particles from Janus drop with high flexibility to control their shapes by in situ photopolymerization. Methods Janus drops are continuously formed as the oil phase breaks up the two laminar flows of a photocurable fluid and a sacrificial template. Our method to generate anisotropic particles includes two routes: In situ polymerization of Janus drop in equilibrium state and evolved drop in nonequilibrium state. Results The resulting drop has allowed us to synthesize hemispheres with flat bottom and 3D particles. Also, the formation of the Janus drop and their evolution is theoretically estimated by spreading coefficient. Conclusions We anticipate that this novel fabrication approach presented in this work can be applied to produce novel functional material in various applications such as selfassembly,photonics, diagnostics, and drug-delivery.
최창형,Naveen Prasad,이내림,이창수 한국바이오칩학회 2008 BioChip Journal Vol.2 No.1
This study is an experimental investigation of a microfluidic method for the formation of droplets and mixing efficiency in continuous microfluidic channels. Droplet size strongly depends on the total aqueous flow rate under a fixed oil flow rate. In the case of different wetting properties, a hydrophobically homogeneous microfluidic channel produces smaller droplets than that of a heterogeneous microfluidic channel b ecause of the different wettability of the formed aqueous droplets. However, high mixing efficiency in the two types of microfluidic channel is achieved by droplet recirculation. Although an increase in droplet size demands a longer mixing time, the microfluidic approach provides rapid mixing and no reagent dispersion. This mixing method in microfluidics can be applied to a variety of chemical syntheses or biochemical reactions at the nanoliter scale. This study is an experimental investigation of a microfluidic method for the formation of droplets and mixing efficiency in continuous microfluidic channels. Droplet size strongly depends on the total aqueous flow rate under a fixed oil flow rate. In the case of different wetting properties, a hydrophobically homogeneous microfluidic channel produces smaller droplets than that of a heterogeneous microfluidic channel b ecause of the different wettability of the formed aqueous droplets. However, high mixing efficiency in the two types of microfluidic channel is achieved by droplet recirculation. Although an increase in droplet size demands a longer mixing time, the microfluidic approach provides rapid mixing and no reagent dispersion. This mixing method in microfluidics can be applied to a variety of chemical syntheses or biochemical reactions at the nanoliter scale.