Imaging cells

We use AFM to image living or fixed cells, and couple AFM imaging to other resolutive imaging techniques such as RICM, TIRF,…

AFM contact mode image of a COS7 cell adhering on a FN pattern

Relevant publication :

Dejardin MJ, Hammerle A, Sadoun A, Hamon Y, Puech PH, Sengupta K*, Limozin L* Lamellipod reconstruction by three dimensional reflection interference contrast nanoscopy (3D-RICN). Nanoletters (2018) Oct 10;18(10):6544-6550

Coupling AFM force mode and simultaneous fluorescence imaging

We developped and easy and cheap coupling between AFM and fluorescence to allow the measurements of stimulation and activation of T cells, montitoring Ca2+ in real time, using an original internal timer signal, and AFM based mechanical stimulation.

Simultaneous recording of forces (red) and calcium fluxes (green) as a function of time for a Fluo4 loaded Jurkat T cell. Fluorescence of non contacted cells in brown.

Stimulation can be performed with continusous contact or successions of timed, short stimulations in order to dissect how the “signalling black box” answers to the same specific signal, but with a given spatial or temporal distribution. This approach, in a way, is a typical physicist method of dissecting the “transfer function” of an unknown system. We extended this technique to study of modifications of mechanical properties of T cells by using photoactivable small GTP-ases family members (eg. Rac-PA) in real time.

Relevant publication

Synchronizing atomic force microscopy force mode and fluorescence microscopy in real time for immune cell stimulation and activation studies. Cazaux S, Sadoun A, Biarnes-Pelicot M, Martinez M, Obeid S, Bongrand P, Limozin L, Puech PH*. Ultramicroscopy. 2016 Jan;160:168-81. doi: 10.1016/j.ultramic.2015.10.014. Epub 2015 Oct 19

Mechanical characterization of cells

We apply AFM force spectroscopy to characterize cell mechanics, in pathological or normal situations. For example, we use PeakForce mechanical mapping and conventional force spectroscopy to determine the mechanical properties of lens cells and cells grown on micropatterns (Hozic et al. 2012; Rigato et al. 2015).

For patterned T cells, see here

For other patterned cells, see the relevant publication

Atomic Force Microscopy Mechanical Mapping of Micropatterned Cells Shows Adhesion Geometry-Dependent Mechanical Response on Local and Global Scales. Rigato A, Rico F, Eghiaian F, Piel M, Scheuring S. ACS Nano. 2015 Jun 23;9(6):5846-56.