Production of AFM wedged cantilevers for stress-relaxation experiments: Uniaxial loading of soft, spherical cells

The fabrication of wedge-shaped cantilevers for Atomic Force Microscopy (AFM) remains a critical yet challenging task, particularly when precision and efficiency are required. In this study, we present a streamlined protocol for producing these wedges using NOA63 UV-curing polymer, which simplifies the process and eliminates the need for dedicated equipment. Our method reduces preparation time while maintaining the mechanical properties of the cantilevers, in line with the manufacturer's specifications. We demonstrate the effectiveness of our wedged cantilevers in stress-relaxation experiments performed by means of AFM and confocal microscopy on primary Chronic Lymphocytic Leukemia cells and the MEC1 cell line. These experiments highlight the effectiveness of using modified cantilevers to consistently apply precise uniaxial loading to soft, spherical cells. This technique offers a marked improvement in fabrication speed and operational ease compared to traditional methods, without compromising the accuracy or performance of the measurements. This protocol is not only time-saving, but also adaptable for use in a wide range of biological applications, making it a valuable tool for AFM-based research in cellular mechanics.

AFM; Cantilever; Cantilever modification; Cell mechanics; Cell shape; Confinement; Leukemia; Spherical cell; Stress-relaxation.