An efficient preservation of a cell-based biosensor chip to achieve a ready-to-use on-site system is still very challenging as the chip contains a living component such as adherent mammalian cells. Herein, we propose a strategy called on-sensor cryopreservation (OSC), which enables the adherent cells to be preserved by freezing (-80 °C) on a biosensor surface, such as the light-addressable potentiometric sensor (LAPS). Adherent cells on rigid surfaces are prone to cryo-injury; thus, the surface was modified to enhance the cell recovery for OSC. It relies on i) the integration of elastic electrospun fibers composed of polyethylene vinyl acetate (PEVA), which has a high thermal expansion coefficient and low glass-transition temperature, and ii) the treatment with O₂ plasma. The modified sensor is integrated into a microfluidic chip system not only to decrease the thermal mass, which is critical for fast thawing, but also to provide a precisely controlled micro-environment. This novel cryo-chip system is effective for keeping cells viable during OSC. As a proof-of-concept for the applicability of a ready-to-use format, the extracellular acidification of cancer cells (CHO-K1) was evaluated by differential LAPS measurements after thawing. Results show, for the first time, that the OSC strategy using the cryo-chip allows label-free and quantitative measurements directly after thawing, which eliminates additional post-thaw culturing steps. The freezing of the chips containing cells at the manufacturing stage and sending them via a cold-chain transport could open up a new possibility for a ready-to-use on-site system.

有效地保存基于细胞的生物传感器芯片以实现即用型现场系统仍然非常具有挑战性，因为该芯片包含诸如粘附的哺乳动物细胞之类的生物成分。在本文中，我们提出了一种称为传感器上超低温保存（OSC）的策略，该策略可使粘附的细胞通过在生物传感器表面（如光寻址电位传感器（LAPS））上冻结（-80°C）而得以保存。刚性表面上的贴壁细胞容易受到冰冻伤害；因此，对表面进行了修饰以增强OSC的细胞回收率。它依赖于：i）由高热膨胀系数和低玻璃化转变温度的聚乙烯乙酸乙烯酯（PEVA）组成的弹性电纺纤维的集成，以及ii）O ₂处理等离子体。改进的传感器集成到微流控芯片系统中，不仅可以减少热质量（这对于快速解冻至关重要），而且还可以提供精确控制的微环境。这种新颖的冷冻芯片系统可有效保持OSC期间细胞的活力。作为即用型形式的适用性的概念验证，融化后通过差异LAPS测量评估癌细胞的细胞外酸化（CHO-K1）。结果首次显示，使用冷冻芯片的OSC策略可在融化后立即进行无标签和定量的测量，从而消除了额外的解冻后培养步骤。