水包油之乳液（oil-in-water (O/W) emulsion）是油在連續相的水中乳化的結果，常需以表面活性劑或聚合物來製備。而奈米顆粒或微粒亦可吸附至油水界面，而穩定O/W的乳化作用，此利用固體顆粒來乳化所得之乳液稱之為皮克林乳液（Pickering emulsion）。本論文研究中，皮克林乳液是以纖維素奈米晶體（Cellulose Nanocrystals，CNCs）及細菌纖維素奈米纖維（Bacterial Cellulose Nanofibers，BCNFs）來製備，利用0.1 wt% CNCs或BCNFs可將苯乙烯（Styrene，St）形成穩定的O/W型皮克林乳液。在油水體積比為1/4下，以CNCs製備的皮克林乳液平均直徑為8.03±2.51 μm，若於水相中添加20 mM NaCl，可提升乳液之穩定性，降低油滴平均直徑為3.32±1.15 μm。而於油相中添加1g奈米磁粉OA-Fe3O4，會降低乳液之穩定性，可得到平均直徑為7.26±2.44 μm的磁性油滴。然而，以BCNFs來製備的皮克林乳液時，油滴大小為6.17±2.34 μm，但在水相中添加20 mM NaCl卻會降低乳液之穩定性，油滴平均直徑會增加為12.62±4.22 μm。將皮克林乳液中之苯乙烯加以聚合，可得核心為聚苯乙烯（Polystyrene，PS），外殼為CNCs或BCNFs之顆粒。BCNFs製備的皮克林乳液可聚合出實心與空心之PS顆粒，比表面積分別為0.79m²/g及1.04m²/g，表面多孔之空心PS顆粒能經由溶劑處理得到表面平整之顆粒。在利用溶於苯乙烯之OA-Fe3O4 NPs可製備磁性皮克林乳液，經聚合作用，可得核心具有磁性，表面具有纖維素覆蓋之顆粒，此顆粒能用於吸附具有纖維素結合功能域之蛋白外，由於顆粒表面上之纖維素是具有－SO3-或－COO-負電荷，能與帶正電性之ε-Polylysine（ε-PL）吸附，修飾成具有正電性之磁性皮克林乳液顆粒，表面之ε-PL具抗菌性，能使此PS微粒成為具有抗菌性之功能性磁性顆粒。

Oil-in-water (O/W) emulsions are usually prepared by emulsification of oil in water in the presence of surfactants or polymers. The nanoparticles or microparticles can also adsorb onto the oil-water interface to stabilize the O/W emulsion which is known as Pickering emulsion. In this work, Pickering emulsions were prepared by using cellulose nanocrystals (CNCs) and bacterial cellulose nanofibers (BCNFs) to stabilize the O/W emulsion. Styrene was employed as oil phase to be emulsified in 0.1 wt% CNCs or BCNFs solution. With oil-water volume ratio of 1: 4, the average diameter of oil droplets in Pickering emulsion prepared by CNCs is 8.03±2.51 μm. With addition of NaCl to 20 mM to the aqueous phase, the stability of emulsion was significantly improved with the average size of oil droplets reduced to 3.32±1.15 μm. The styrene in the Pickering emulsion could be polymerized to obtain polystyrene (PS) microparticles with a shell of CNCs or BCNFs. Hollow PS particles with open pores could be obtained by freeze-drying the polymerized emulsion prepared by BCNFs with specific surface areas of 1.04 m2/g. Magnetic Pickering emulsion could also be prepared by adding oleic acid surface modified Fe3O4 NPs in styrene. After polymerization, microparticles with magnetic core and cellulose-coated surface could be obtained. The particle can be used to specifically capture recombinant proteins fused with cellulose-binding domain. Since the CNCs or BCNFs shell of the microparticles carrie a negative charge (－SO3- or－COO-), the positively charged ε-polylysine (ε-PL) can be easily grafted onto the surface via electrostatic interaction. The grafted ε-PL will confer the particles with antimicrobial activity to kill the bacteria encountered.

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