Liu Yang, Nambu Natalia Oshima, Taya Masahito
Division of Chemical Engineering, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka, 560-8531, Japan.
Department and School of Medicine, Federal University of Rio Grande do Sul, R. Ramiro Barcelos, 2400 - Santa Cecilia, Porto Alegre, Rio Grande do Sul, 90035-003, Brazil.
Biomed Microdevices. 2017 Sep;19(3):55. doi: 10.1007/s10544-017-0198-8.
Microfluidic methods are frequently used to produce cell-laden microgels for various biomedical purposes. Such microfluidic methods generally employ oil-water systems. The poor distribution of crosslinking reagents in the oil phase limits the available gelation strategies. Extracting the microgel from the oil-phase also reduces its production efficiency. In this study, an aqueous two-phase system (ATPS) involving dextran (DEX) and polyethylene glycol (PEG) was used to prepare cell-laden microgel. This avoided the problems associated with an oil phase. The microgel precursor polymers and crosslinking reagents were dispersed in the DEX and PEG phases, respectively. The ultra-low interfacial tension of the ATPS hindered droplet formation. A co-flow microfluidic device was fabricated to overcome this problem. The device incorporated a square-wave-changing injection force, to improve the efficiency of droplet formation. The microgel precursor (including alginate and carboxymethyl cellulose derivatives possessing phenolic hydroxyl moieties) could be dispersed in the DEX solution at various concentrations. Uniform droplets were formed with controllable diameters, and were sequentially converted to microgel by horseradish peroxidase-catalyzed crosslinking. Cells were dispersed in the DEX phase with the microgel precursor polymer, and retained their high viability and proliferation in the resulting microgel. The solubility of gelatin derivatives in the DEX phase was low, but was sufficient to impart cell adhesion properties on the microgel.
微流控方法经常被用于制备用于各种生物医学目的的载细胞微凝胶。此类微流控方法通常采用油-水体系。交联试剂在油相中的分布不佳限制了可用的凝胶化策略。从油相中提取微凝胶也会降低其生产效率。在本研究中，一种涉及右旋糖酐（DEX）和聚乙二醇（PEG）的水相两相体系（ATPS）被用于制备载细胞微凝胶。这避免了与油相相关的问题。微凝胶前体聚合物和交联试剂分别分散在DEX和PEG相中。ATPS的超低界面张力阻碍了液滴的形成。制造了一种共流微流控装置来克服这一问题。该装置采用了方波变化的注入力，以提高液滴形成的效率。微凝胶前体（包括具有酚羟基部分的藻酸盐和羧甲基纤维素衍生物）可以以各种浓度分散在DEX溶液中。形成了直径可控的均匀液滴，并通过辣根过氧化物酶催化交联依次转化为微凝胶。细胞与微凝胶前体聚合物一起分散在DEX相中，并在所得微凝胶中保持其高活力和增殖能力。明胶衍生物在DEX相中的溶解度较低，但足以赋予微凝胶细胞粘附特性。
