Simulation of 3D nanomanipulation for rough spherical elastic and viscoelastic particles in a liquid medium; experimentally determination of cell's roughness parameters and Hamaker constant's correction.

Due to the softness and vulnerability of biological cells, in manipulation operations, it is not possible to insert excessive force to move these cells. Also, cells in their living environment face with many dynamic factors; therefore, in order to prevent their destruction and death, consideration the environmental conditions, the theoretical studies that underlie the laboratory research should be closer to the actual results. So, in this article by simultaneous consideration of cell's viscoelasticity and asperities on its surface, as well as the correction of the viscoelastic constant in the liquid medium, the effects of the number of asperities on the contact area between cell and substrate on the manipulation process are investigated and by considering different mediums effects, cell's roughness and developed Hamaker for viscoelastic state, more accurate results of simulations are obtained. On the other hand, atomic force microscopy is also a powerful and multifunctional imaging device that provides observation and manipulation of biological samples, including single-cells, in a liquid medium. Consequently, in this study, using this device, the topography of the benign breast cancer cell is carried out in a liquid medium in contact mode. To correct the viscoelastic Hamaker constant, results are obtained using the Gwyddion software for extracting the roughness radius and the particle's height distribution function. In addition, simulation of the 3D manipulation for elastic and viscoelastic spherical bioactive particles in both air and liquid mediums is done applying particle's roughness with elastic and viscoelastic Hamaker constants. Results indicate that in the liquid medium due to changes in the adhesion force as well as the presence of drag force and surface tension, the critical force is reduced compared to air medium, and the effect of particle's roughness on the critical force and time is related to the number of asperities on the contact surface. Also, results are in good agreement with results of applying the particle's folding coefficient in the manipulation. In the second phase of the manipulation, the change trend in the manipulation force varies in different operating conditions.