determine the magnitue and direction of the anchoring force

Attempts to bypass these shortcomings, by applying micro-patterning of adhesive islands 14, 15 or lithographic photoresist into ordered arrays 16, are hampered by major drawbacks such as the poor spatial resolution or the introduction of intrusive topographical features. These approaches yield high-resolution in- and out-of-plane force maps but require the additional acquisition of a reference (load-free) image, typically captured on cell removal and destruction, which markedly complicates experimental procedures and precludes post-processing such as the colocalization with immunofluorescence staining. Continuum TFM methods exploit elastic substrates containing randomly dispersed fluorescent beads 11, 12, 13. Of these, lower-resolution discrete methods such as arrays of elastic micro-posts 6, 7 allow the estimation of forces from a single image, yet carry significant limitations to the detection of out-of-plane components of traction forces, as well as artefacts due to their non-continuous, structured and intrusive nature 5, 8, 9, 10. In the last two decades multiple protocols for the measurement of cell-generated tractions have been developed, based on the optical detection of force-dependent deformations of compliant substrates 3, 4, 5. Traction force microscopy (TFM) provides a powerful tool to experimentally access cellular forces. The biological function of this mechanical machinery goes beyond the simple physical anchoring and conveys environmental signals, which cells sense and respond to 2.

These forces are transmitted to the extracellular surroundings through integrin-based adhesions (that is, focal adhesions) and enable shape changes and directional migration 1. We demonstrate the undisrupted reference-free acquisition and quantification of high-resolution continuous force fields, and the simultaneous capability of this method to correlatively overlap traction forces with spatial localization of proteins revealed using immunofluorescence methods.Ĭells exert forces on their environment, mainly but not exclusively through the contractile acto-myosin machinery. The method is based on electrohydrodynamic nanodrip-printing of quantum dots into confocal monocrystalline arrays, rendering individually identifiable point light sources on compliant substrates. Here we introduce a novel method allowing a one-shot (live) acquisition of continuous in- and out-of-plane traction fields with high sensitivity.

Despite progress, important limitations with intrusion effects in low resolution 2D pillar-based methods or disruptive intermediate steps of cell removal and substrate relaxation in high-resolution continuum TFM methods need to be overcome. Traction force microscopy (TFM) enables determination of the actuating forces. The mechanical wiring between cells and their surroundings is fundamental to the regulation of complex biological processes during tissue development, repair or pathology.

Determine the magnitue and direction of the anchoring force