Cryopreservation of a cell-based biosensor chip modified with elastic polymer fibers enabling ready-to-use on-site applications

• Published in: Biosensors & bioelectronics 2021-04, Vol.177, p.112983-112983, Article 112983
• Main Authors: Özsoylu, Dua, Isık, Tuğba, Demir, Mustafa M., Schöning, Michael J., Wagner, Torsten
• Format: Article
• Language: English
• Subjects: Animals; Biosensing Techniques; Chemical imaging; Cryo-chip; Cryopreservation; Extracellular acidification; Freezing; Light-addressable potentiometric sensor; On-sensor cryopreservation; Polymers; Potentiometry; Ready-to-use
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2021.112983

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. [Display omitted] •A novel strategy, on-sensor cryopreservation (OSC) is revealed for biopreservation of cell-based biosensors.•Modification of a rigid sensor surface with elastic electrospun fibers ensures cell survival for OSC.•Increased wettability of the hybrid (elastic/rigid) structure by plasma treatment contributes the improved cell recovery.•Cryo-chip enables label-free and quantitative monitoring of the extracellular acidification (EA) directly after thawing.•The ready-to-use on-site system using the cryo-chip is validated by differential chemical images of EA.