Cell force measurements in 3D microfabricated environments based on compliant cantilevers

Abstract

We report the fabrication, functionalization and testing of microdevices for cell culture and cell traction force measurements in three-dimensions (3D). The devices are composed of bent cantilevers patterned with cell-adhesive spots not lying on the same plane, and thus suspending cells in 3D. The cantilevers are soft enough to undergo micrometric deflections when cells pull on them, allowing cell forces to be measured by means of optical microscopy. Since individual cantilevers are mechanically independent of each other, cell traction forces are determined directly from cantilever deflections. This proves the potential of these new devices as a tool for the quantification of cell mechanics in a system with well-defined 3D geometry and mechanical properties.

Single-cell 3D Bio-MEMS environment with engineered geometry and physiologically relevant stiffnesses

“…4 Ti thicknesses have been tested (30, 60, 110, and 150 nm), combining them with each of the 4 silica thicknesses, for a total of 16 different combinations.…”

“…Two cell lines have been tested: mouse embryo fibroblasts (MEF, also used elsewhere [4]), and rat embryo fibroblasts (REF), used for the first time in this kind of device. First, the Au spots deposited along the cantilevers are selectively functionalized with an adhesive peptide (Figure 7), in order to facilitate the formation of cellular focal adhesions (FAs).…”

“…MEMS technologies represent an opportunity to engineer the features of artificial cell microenvironments at the cellular or sub-cellular scale, enriching them with controlled topographies, patterns, mechanical structures and microfluidics [1,2,3]. Earlier results showed the possibility to use bent cantilevers as 3D cell culture substrate with potential applications in cell traction forces measurements [4]. Yet, these prototypical devices were limited to have one single value of stiffness, while the rigidity of the microenvironment has been shown to greatly affect cell functions, such as cytoskeletal organization and stem cell differentiation [2].…”

Cellular Biomechanics in Drug Screening and Evaluation: Mechanopharmacology

“…Pseudo-3D techniques have been attempted by growing cells between micropillars [95], or by hanging cells using bent cantilever beams [96]. However, these methods do not fully mimic the physiological nature of cells embedded in 3D, particularly because the ensemble responses of multicellular structures are not accounted for in these assays.…”

Micro- and nanodevices integrated with biomolecular probes

“…Even though a 3D environment was produced for the cells, this approach is susceptible to computationally intensive data processing. In another study, pre-bent, flexible, and ECM protein functionalized cantilevers in a blossoming flower configuration were fabricated to measure traction forces of cells in 3D (Marelli et al, 2014). A limitation of this method is the restriction of cells in a confined configuration, which does not allow cell migration and cell–cell interactions.…”