肿瘤微环境（TME）中的氧水平在调节细胞命运（例如增殖、迁移、凋亡等）中起着至关重要的作用。为了更好地阐明缺氧如何影响肿瘤细胞行为，采用了一系列微流体策略来产生覆盖两种缺氧阴离子的氧梯度。然而，在大多数研究中，一些化学物质被引入到微流控芯片中，导致其潜在的生物相容性较差。常见的线性变化的氧梯度不允许准确分析特定氧浓度对肿瘤细胞的影响。本文基于气体扩散的物理方法，提出了一种集成氧梯度发生器的微流控装置，用于研究不同缺氧水平对肿瘤细胞反应的影响。该器件由三层组成，即上层、薄膜层和底层。上层用于引入初始气体并产生气体形式的氧气梯度。底层用于引入细胞和培养基。薄膜层将前两层分开，使气体通过它从顶部扩散到底部。底层的氧梯度最终以溶解氧的形式产生。该装置采用微加工技术制造。通过有限元模拟评估了装置的结构和工作参数对氧梯度的影响。使用氧敏感荧光材料来表征细胞培养通道中的氧梯度。培养48小时后比较特定氧水平下HeLa细胞的增殖和形态。阶梯状分布的氧梯度表明该微流控装置可以为体外细胞研究和揭示与特定缺氧微环境相关的肿瘤转移机制提供一个前瞻性的实验平台。

The oxygen level in the tumor microenvironment (TME) plays a critical role in regulating cell fates such as proliferation, migration, apoptosis, and so forth. To better elucidate how hypoxia affects tumor cell behaviors, a series of microfluidic strategies have been utilized to generate an oxygen gradient covering both hypoxia anions. However, in most studies, some chemicals are introduced into microfluidic chips, causing the potential of their poor biocompatibility. The common oxygen gradient with linear variation does not allow the effects of specific oxygen concentrations on tumor cells to be analyzed accurately. In this paper, based on the physical method of gas diffusion, a microfluidic device integrated with an oxygen gradient generator is proposed for investigating effects of different hypoxia levels on responses of tumor cells. This device consists of three layers, i.e., upper layer, thin film layer, and bottom layer. The upper layer is used for introducing the initial gas and generating an oxygen gradient in the form of gas. The bottom layer is used for introducing cells and culture medium. The thin film layer separates the former two layers, allowing the gas to diffuse from the top to the bottom through it. The oxygen gradient in the bottom layer is finally generated in the form of dissolved oxygen. The device is fabricated using microfabrication technology. The effects of structural and working parameters of the device on the oxygen gradient are evaluated by finite element simulation. The oxygen gradient in cell culture channels is characterized by using oxygen-sensitive fluorescence materials. The proliferation and morphology of HeLa cells under specific oxygen levels are compared after culturing for 48 h. The oxygen gradient with a ladder-like distribution demonstrates that this microfluidic device can provide a prospective experimental platform for in vitro cell studies and revelation of the mechanism of tumor metastasis associated with a specific hypoxic microenvironment.