In vitro studies are the first step toward understanding the biological effects of particulate matter. As a more realistic exposure strategy than submerged culture approaches, air-liquid interface (ALI) in vitro exposure systems are gaining interest. One challenge with ALI systems is determining accurate particle mass deposition. Although a few commercially available ALI systems are equipped with online mass deposition monitoring, most studies use indirect methods to estimate mass doses. These different indirect methods may contribute to inconsistencies in the results from in vitro studies of aerosolized nanoparticles. This study explored the effectiveness of using a commercially available Quartz Crystal Microbalance (QCM) to estimate the real-time, particle-mass deposition inside an electrostatic, parallel-flow, ALI system. The QCM system required minor modifications, including custom-designed and fabricated headers. Three QCM systems were simultaneously placed in three of the six wells in the ALI exposure chamber to evaluate the uniformity of particle deposition. The measurements from fluorescein dosimetry and QCM revealed an uneven deposition between these six wells. The performance of the QCM system was also evaluated using two different methods. First, using fluorescein deposition in one well, depositions in three other wells were estimated, which was then compared to the actual QCM readings. Second, using the QCM measured deposition in one well, the deposition in three other wells was estimated and compared to deposition measured by fluorescein dosimetry. For both methods, the expected and actual deposition yields a linear fit with the slope ~1. This good fit suggests that QCM systems can be used to measure real-time mass deposition in an electrostatic ALI system.

中文翻译：

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在静电、平行流、气液界面曝光系统中使用石英晶体微天平测定实时质量沉积


体外研究是了解颗粒物生物效应的第一步。作为一种比深层培养方法更现实的暴露策略，气液界面（ALI）体外暴露系统越来越受到人们的关注。 ALI 系统面临的一项挑战是确定精确的颗粒质量沉积。尽管一些商用 ALI 系统配备了在线质量沉积监测，但大多数研究使用间接方法来估计质量剂量。这些不同的间接方法可能会导致雾化纳米粒子的体外研究结果不一致。本研究探讨了使用市售石英晶体微天平 (QCM) 来估计静电平行流 ALI 系统内实时颗粒质量沉积的有效性。 QCM 系统需要进行少量修改，包括定制设计和制造的接头座。三个 QCM 系统同时放置在 ALI 暴露室的六个孔中的三个中，以评估颗粒沉积的均匀性。荧光素剂量测定和 QCM 的测量结果显示这六个孔之间的沉积不均匀。 QCM 系统的性能也使用两种不同的方法进行了评估。首先，使用一个孔中的荧光素沉积来估计其他三个孔中的沉积，然后将其与实际的 QCM 读数进行比较。其次，使用 QCM 测量的一个孔中的沉积，估计其他三个孔中的沉积，并与荧光素剂量测定法测量的沉积进行比较。对于这两种方法，预期沉积和实际沉积产生斜率 ~1 的线性拟合。这种良好的配合表明 QCM 系统可用于测量静电 ALI 系统中的实时质量沉积。