Choi Seung Ho, Yoon Jun Jin, Park Tae Gwan
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Taejon, 305-701, Korea (South).
J Colloid Interface Sci. 2002 Jul 1;251(1):57-63. doi: 10.1006/jcis.2002.8427.
Poly(N-isopropylacrylamide-co-acrylic acid) hydrogel submicrometer particles were prepared by free radical copolymerization of N-isopropylacrylamide and acrylic acid in the presence of a crosslinker above the lower critical solution temperature (LCST). They exhibited a reversible swelling and deswelling behavior: ca. 200-nm diameter below the LCST and ca. 100-nm diameter above the LCST. The hydrogel particles were tagged with fluorescent dye (FITC) in order to monitor the extent of cellular uptake and were further modified with galactose moieties to evaluate the extent of receptor-mediated endocytosis against HepG2 cells. Flow cytometry and confocal microscopy were used to investigate cellular uptake behaviors of the submicrometer particles. It was found that the extent of cellular uptake of submicrometer particles was far greater above the LCST than below the LCST, suggesting that smaller particles were taken up more readily within cells. When the submicrometer particles were galactosylated, the extent of cellular uptake increased dramatically due to receptor-mediated endocytosis. This study proposes a new possibility of controlling intracellular events such as protein and gene expression by a thermally modulated endocytosis process using thermo-sensitive microgel beads.
通过在低于最低临界溶液温度（LCST）时，使N-异丙基丙烯酰胺和丙烯酸在交联剂存在下进行自由基共聚，制备了聚（N-异丙基丙烯酰胺-共-丙烯酸）水凝胶亚微米颗粒。它们表现出可逆的溶胀和去溶胀行为：在LCST以下直径约为200纳米，在LCST以上直径约为100纳米。为了监测细胞摄取程度，用水凝胶颗粒标记荧光染料（FITC），并进一步用半乳糖部分修饰，以评估针对HepG2细胞的受体介导的内吞作用程度。使用流式细胞术和共聚焦显微镜研究亚微米颗粒的细胞摄取行为。发现亚微米颗粒在LCST以上的细胞摄取程度远高于在LCST以下，这表明较小的颗粒在细胞内更容易被摄取。当亚微米颗粒被半乳糖基化时，由于受体介导的内吞作用，细胞摄取程度急剧增加。本研究提出了一种通过使用热敏微凝胶珠的热调节内吞过程来控制细胞内事件（如蛋白质和基因表达）的新可能性。
