Hydrogel Beads
The validation of our mechanical techniques relies on utilizing mechanical calibration standards with precisely defined stiffness, mimicking the material properties of cells. Fabricating such calibration particles on the microscale poses significant challenges. Girardo et al. addressed this challenge by introducing hydrogel beads made from polyacrylamide using a microfluidic droplet generator. The resulting beads range in size from 10 to 20 µm and have Young’s moduli from below 1 to 10 kPa (1).
We routinely employ these beads to assess the stresses within our devices and validate models for cell deformation (2,3). Additionally, these beads can be inserted into tissues to measure stresses within the tissue itself (4), or to build up mechanically patterned 3D growth scaffolds (5).
The hydrogel beads are produced for us by the TDSU Lab-on-a-Chip. You can find more information about the production process on their page.
[1] Girardo S, Träber N, Wagner K, Cojoc G, Herold C, Goswami R, et al. Standardized microgel beads as elastic cell mechanical probes. J Mater Chem B. 2018. 6(39):6245–6261. https://doi.org/10.1039/C8TB01421C
[2] Wittwer LD, Reichel F, Müller P, Guck J, Aland S. A new hyperelastic lookup table for RT-DC. Soft Matter. 2023. 19(11):2064–2073. https://doi.org/10.1039/D2SM01418A
[3] Reichel F, Goswami R, Girardo S, Guck J. High-throughput viscoelastic characterization of cells in hyperbolic microchannels. Lab Chip. 2024. 24(9):2440–2453. https://doi.org/10.1039/D3LC01061A
[4] Träber N, Uhlmann K, Girardo S, Kesavan G, Wagner K, Friedrichs J, et al. Polyacrylamide Bead Sensors for in vivo Quantification of Cell-Scale Stress in Zebrafish Development. Sci Rep. 2019. 9(1):17031. https://doi.org/10.1038/s41598-019-53425-6
[5] Wagner K, Girardo S, Goswami R, Rosso G, Ulbricht E, Müller P, Soteriou D, Träber N, Guck J. Colloidal crystals of compliant microgel beads to study cell migration and mechanosensitivity in 3D. Soft Matter. 2019. 15:9776-9787. https://doi.org/10.1039/C9SM01226E
