Browsing by Author "Huang, Keng-Shiang"

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Calcium alginate microcapsule generation on a microfluidic system fabricated using the optical disk process
(2007-08-01)
Huang, Keng-Shiang
;
Liu, Ming-Kai
;
Wu, Chun-Han
;
Yen, Yu-Tang
;
Lin, Yu-Cheng
This paper describes the generation of monodisperse calcium alginate (Ca-alginate) microcapsules on a microfluidic platform using the commercial optical disk process. Our strategy is based on combining the rapid injection molding process for a cross-junction microchannel with the sheath focusing effect to form uniform water-in-oil (w/o) emulsions. These emulsions, consisting of 1.5% (w/v) sodium alginate (Na-alginate), are then dripped into a solution containing 20% (w/v) calcium chloride (CaCl2) creating Ca-alginate microparticles in an efficient manner. This paper demonstrates that the size of Ca-alginate microparticles can be controlled from 20 mu m to 50 mu m in diameter with a variation of less than 10%, simply by altering the relative sheath/sample flow rate ratio. Experimental data show that for a given fixed dispersed phase flow (sample flow), the emulsion size decreases as the average flow rate of the continuous phase flow (sheath flow) increases. The proposed microfluidic platform is capable of generating relatively uniform emulsions and has the advantages of active control of the emulsion diameter, a simple and low cost process and a high throughput.
Facile Synthesis of Radial-Like Macroporous Superparamagnetic Chitosan Spheres with In-Situ Co-Precipitation and Gelation of Ferro-Gels
(2012-11-30)
Yang, Chih-Hui
;
Wang, Chih-Yu
;
Huang, Keng-Shiang
;
Yeh, Chen-Sheng
;
Wang, Andrew H. -J.
Macroporous chitosan spheres encapsulating superparamagnetic iron oxide nanoparticles were synthesized by a facile and effective one-step fabrication process. Ferro-gels containing ferrous cations, ferric cations and chitosan were dropped into a sodium hydroxide solution through a syringe pump. In addition, a sodium hydroxide solution was employed for both gelation (chitosan) and co-precipitation (ferrous cations and ferric cations) of the ferro-gels. The results showed that the in-situ co-precipitation of ferro-ions gave rise to a radial morphology with non-spheroid macro pores (large cavities) inside the chitosan spheres. The particle size of iron oxide can be adjusted from 2.5 nm to 5.4 nm by tuning the concentration of the sodium hydroxide solution. Using Fourier Transform Infrared Spectroscopy and X-ray diffraction spectra, the synthesized nanoparticles were illustrated as Fe3O4 nanoparticles. In addition, the prepared macroporous chitosan spheres presented a super-paramagnetic behaviour at room temperature with a saturation magnetization value as high as ca. 18 emu/g. The cytotoxicity was estimated using cell viability by incubating doses (0 similar to 1000 mu g/mL) of the macroporous chitosan spheres. The result showed good viability (above 80%) with alginate chitosan particles below 1000 mu g/mL, indicating that macroporous chitosan spheres were potentially useful for biomedical applications in the future.
Microfluidic Synthesis of Microfibers for Magnetic-Responsive Controlled Drug Release and Cell Culture
(2012-03-28)
Lin, Yung-Sheng
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Huang, Keng-Shiang
;
Yang, Chih-Hui
;
Wang, Chih-Yu
;
Yang, Yuh-Shyong
This study demonstrated the fabrication of alginate microfibers using a modular microfluidic system for magnetic-responsive controlled drug release and cell culture. A novel two-dimensional fluid-focusing technique with multi-inlets and junctions was used to spatiotemporally control the continuous laminar flow of alginate solutions. The diameter of the manufactured microfibers, which ranged from 211 mm to 364 mm, could be well controlled by changing the flow rate of the continuous phase. While the model drug, diclofenac, was encapsulated into microfibers, the drug release profile exhibited the characteristic of a proper and steady release. Furthermore, the diclofenac release kinetics from the magnetic iron oxide-loaded microfibers could be controlled externally, allowing for a rapid drug release by applying a magnetic force. In addition, the successful culture of glioblastoma multiforme cells in the microfibers demonstrated a good structural integrity and environment to grow cells that could be applied in drug screening for targeting cancer cells. The proposed microfluidic system has the advantages of ease of fabrication, simplicity, and a fast and low-cost process that is capable of generating functional microfibers with the potential for biomedical applications, such as drug controlled release and cell culture.
Synthesis of uniform core-shell gelatin-alginate microparticles as intestine-released oral delivery drug carrier
(2014-02-01)
Huang, Keng-Shiang
;
Yang, Chih-Hui
;
Kung, Chao-Ping
;
Grumezescu, Alexandru Mihai
;
Ker, Ming-Dou
A core-shell gelatin-alginate composite used for intestine-released oral delivery drug carrier was synthesized through microfluidic technique. At the fixed continuous phase flow rate, the size of the core-shell gelatin-alginate microparticles increases with the dispersed phase flow rate, and monodispersity can be retained (the variation coefficient for the diameter distribution can be kept less than 10%). The fabricated microparticles could remain intact in gastric juice for at least 3 h, indicating that the gelatin core could be well protected by alginate shell in acid environment. However, the alginate shell of the microparticles would swell or collapse in alkali environment in half an hour, assuring the controlled drug release in intestinal juice. The fabricated uniform core-shell gelatin-alginate microparticles were potential as pH-responsive drug carriers.
Using a CD-like microfluidic platform for uniform calcium alginate drug carrier generation
(2007-01-01)
Liu, Ming-Kai
;
Huang, Keng-Shiang
;
Chang, Jia-Yaw
;
Wu, Chun-Han
;
Lin, Yu-Cheng
In this paper the manipulation of monodisperse Ca-alginate microparticles using a polymer'-based CD-like microfluidic platform and a reaction of external gelation is presented. Our strategy was based on associating the rapid injection molding process for cross-junction microchannel with the sheath focusing effect to form uniform water-in-oil (w/o) emulsions. These fine emulsions, consisting of 1.5% w/v Na-alginate, were then dripped into an oil solution containing 20% w/v calcium chloride (CaCl2) to accomplish Ca-alginate microspheres in an efficient manner. We have demonstrated that one can control the size of Ca-alginate microparticles from 20 mu m to 50 mu m in diameter (with a variation less than 10%) by altering the relative sheath/sample flow rate ratio. Experimental data showed that for a given fixed dispersed phase flow (sample flow), the emulsion size decreased as the average velocity of the continuous phase (oil flow) increased. The proposed CD-like microfluidic platform is capable of generating relatively uniform micro-droplets and has the advantages of active control of droplet diameter, simple and low cost process, and high throughput.