Study of Microfluidic T-junction and External/Internal Gelation Reaction for Manipulating the Production of Uniform Alginate Microcapsules: Encapsulation of Nanoparticles

• Main Authors: Sheng-ji Lee, 李勝記
• Other Authors: Yu-cheng Lin
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/56942847977480891659

碩士 === 國立成功大學 === 工程科學系碩博士班 === 95 === This study describes the process of formation of monodisperse calcium alginate microcapsules by using microfluidic T-junction geometries. We focus on the investigation of the velocity fields and pressure fields. The flow inside the module is studied by means of computational fluid dynamics (CFD-RC®). Based on sheath force, Water-in-Oil (W/O) emulsions of an aqueous solution of a biopolymer are emulsified in an oil phase. In the external gelation method, these fine emulsions, consisting of 1.5% w/v Na-alginates, are then dripped into a solution of 20% calcium salt to accomplish Ca-alginate microparticles (Ca-alg MPs) in an efficient manner. In the internal gelation method, these fine emulsions, consisting of 0.5% w/v Na-alginate and calcium carbonate, are then dripped into an oil solution containing 20% v/v glacial acetic acid and 1% v/v Tween 80 to accomplish Ca-alg MPs in an efficient manner. The mechanism is that acetic acid reacts with the calcium carbonate to release the calcium ions, and these calcium ions are then cross-linking with the Na-alginate to produce Ca-alg MPs. Three main topics: (1) the emulsion sizes under oil flow rate and sample flow rate. (2) Effects of viscosity on the emulsion sizes. (3) We examined the encapsulation of nanoparticles (AgNPs and AuNPs), to verify the applicability of the microfluidic technique. Experimental data show that emulsions with diameters ranging from 70 µm to 300 µm with a variation less than 10% are precisely generated. The size and gap of the emulsions are tunable by adjusting the relative sheath/sample flow rate ratio. The approach in manipulation of microparticles will provide many potential usages for pharmaceutical application. The proposed method has advantages of being readily controlled; cost-effective and easy to operate, together with its ability to produces a uniform size and gap.