Study of the micro beads and nano particles diffusion in living cells

• Grant number: 11/18322-9
• Support type: Regular Research Grants
• Duration: February 01, 2012 - October 31, 2013
• Field of knowledge: Interdisciplinary Subjects
• Principal Investigator: Adriano Mesquita Alencar
• Grantee: Adriano Mesquita Alencar
• Home Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Assoc. researchers: Alexandre da Costa Pereira

Abstract

In contrast with the classical diffusion, in which there is a linear dependence of the mean square displacement on the timescale t, in anomalous diffusion this dependence is not linear, ie we have a diffusion coefficient other than 1. If this coefficient is greater than 1, we have a process called superdifusivo, and if less than 1, subdifusivo. Complex fluids in general does not have a single value of this coefficient, making the characterization and understanding of its characteristics more difficult. One of the ways used to study diffusion and viscoelastic properties of complex fluids, such as living cells, is observing the dynamics of microspheres. For these complex fluids, the characterization of viscoelastic properties is a key step in the characterization of cell phenotype and various aspects of basic physiology. The complex elastic modulus can be characterized by a method known as Optical Magnetic Twisting Microscopy (OMTC). However, the correlation between the complex modulus and the diffusive properties are still unclear. Specifically for the smooth muscle cells, it has been found a similarity to soft glassy materials, as evidenced in certain cellular functions such as division, contraction, diffusion, which require that the cells show similarly to a liquid flow, while for other functions such as maintaining their cellular structure, it should appear more rigid. Our main goal is to understand the diffusive processes in complex structures of biological interest using microspheres compared with the values of complex modulus obtained via OMTC. The experimental results are compared with a mathematical model, type random walker, which will produce images similar to those observed by our microscope. We will analyze the images from the microscope and the mathematical model. This comparison between experiment and mathematical model will test our hypotheses while increasing our understanding of the mechanical properties of complex fluids. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

ALENCAR, ADRIANO MESQUITA; AYRES FERRAZ, MARIANA SACRINI; PARK, CHAN YOUNG; MILLET, EMIL; TREPAT, XAVIER; FREDBERG, JEFFREY J.; BUTLER, JAMES P. Non-equilibrium cytoquake dynamics in cytoskeletal remodeling and stabilization. SOFT MATTER, v. 12, n. 41, p. 8506-8511, 2016. Web of Science Citations: 3.