마이크로플루딕스를 이용한 단분산성 중공형 하이드로젤 마이크로입자의 제조 및 투과 제어에 대한 연구

Abstract

We introduce a flexible and straightforward method for generating monodisperse complex hydrogel microparticles. For this, water-in-oil (W/O) emulsions were generated in a microcapillary device and then the emulsion drops were photo-polymerized to transfer them to hydrogel particles. The hydrogel microparticles were made of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) that has an enhanced biocompatibility due to the phosphatidyl choline moiety in the backbone. The average mesh size of the hydrogel network, which is 50 Å, was estimated on the basis of the Peppas–Merrill equation. This mesh size was experimentally confirmed again by NMR cryoporometry analysis and permeation test for dextran probes. Furthermore, to diversify the applicability of microfluidic technology, oil-in-water-in-oil (O/W/O) double emulsions were also fabricated using the co-axial jetting of three combined flows in the micro-channel. Then the aqueous shell was polymerized to give rise to hollow-structured hydrogel microparticles. Finally, we have shown that the microfluidic approach is useful for fabrication of complex hydrogel microparticles that have potential uses in drug immobilization and delivery. In our continued study, we introduce generation of hollow-structured PMPC hydrogel particles whose interfaces were patched with graphene oxide (GO) platelets. Permeability control through the hydrogel phase is limited due to its intrinsic loose network nature. So we need to develop a method to completely encapsulate small molecules in the hydrogel network. The whole fabrication procedure was carried out in a microcapillary device in a single step. GO platelets have an ability to adhere to both O/W and W/O interfaces. Taking advantages of this behavior, we generated monodisperse O/W/O double emulsion whose interfaces were patched with GO platelets. Solidification of the aqueous middle phase to the hydrogel phase gave rise to uniform GO patched hydrogel microcapsules. GO membrane is confirmed by analyzing Raman spectra and SEM images. Furthermore, we demonstrated that the permeation of molecules through the shell could be controlled even to small molecular length scales due to the adsorption of GO.