Experimental and numerical responses of fibroblast and epithelial cells to the frequency of electric toothbrush.

In the oral environment, fibroblast and gingival epithelial cells undergo distinct forces. Chewing, brushing, or force interactions with dental materials like implants can produce these forces. The behavior and response of these cells to forces are determined by their stiffness. Additionally, this behavior can be crucial in mechanosensory and tissue development. In this study, after being cultured using nanomagnet materials, fibroblast and epithelial cells were subjected to magnetic tweezers cytometry testing, and the viscoelastic model was used to determine their stiffness. The reaction of single gingival cells was modeled by determining the stiffness of cells at Gel Point frequencies and the operating frequency of electric toothbrushes and employing the Finite Element Method (FEM). Epithelial cell and fibroblast gel points took place at frequencies of 5Hz and 3Hz, respectively. At these frequencies, the behavior of cells is both quasi-solid and fluid. In addition, the findings of the finite element analysis demonstrated that the cells undergo a greater degree of deformation at the Gel point frequency compared to the operating frequency of toothbrushes. This quantity was approximately 331 times greater in epithelial cells, which reached a maximum of 7.114 µm. Additionally, the maximal fibroblast cell deformation at 3Hz frequency was determined to be 2.981 µm, which is roughly 117 times that at 150Hz frequency.

An investigation of the viscoelastic behavior of MCF-10A and MCF-7 cells.

Breast cancer is the most frequent female malignancy in the world. In this regard, cancer detection by assessing the biomechanical properties of cells is a promising method in oncology. Cell state can be identified by studying viscosity behavior; however, a more complex understanding of cells requires a profound insight into the solidity and fluidity of cells via the characterization of cell viscoelasticity. The present study aimed to compare the viscoelasticity of healthy human breast epithelial cells (MCF-10A) with that of cancerous cells (MCF 7). The experiment included the addition of nano magnetic particles (NMP) to the cell culture environment and placement of the Petri Dishes under a microscope after the completion of primary culture stages and, ultimately, adoption of a magnetic tweezer technique to perform a creep test. A viscoelastic model of cells was suggested with discrete differential equations for both groups of healthy and cancerous cells after obtaining information about cell membrane movements and performing image processes on these data. A comparison of cell stiffness was made under two conditions of static and dynamic. According to the findings, cancerous static stiffness was lower than that of healthy cells by a factor of 3.5. The creep test results showed that MCF 7 cells would exhibit solid-like behavior. At a higher gel point frequency, these cells emerged more solidity compared to their corresponding healthy cells. The obtained results revealed the clear changes in cancerous cells' viscoelastic properties and the potential alterations of their cytoskeleton.

Short-term effects of X-ray on viscoelastic properties of epithelial cells.

Examining the effects of ionizing radiation on the living cell is significant due to its usage in recent centuries. Investigations into the long- and short-term effects of ionizing radiation began simultaneously with its discovery. Previous studies were done on the effects of radiation on cell DNA or the biochemical cycle based on the electromagnetic radiation wavelength, intensity, and exposure time. Considering some dependent parameters like cell communication, the differentiation and the mechanical interactions of intercellular environment, and cell mechanical properties, the effects of ionizing radiation on the viscoelastic properties of cells seem to be important. The current research investigated the short-term biomechanical effects of ionizing radiation and examined the mechanical properties of cells using magnetic tweezer cytometry with nanomagnetic particles. To evaluate these effects, cells were incubated with nanomagnetic particles and then separated into controlled and irradiated groups. A 3 mGy cm2 X-ray was radiated to the irradiated group for 0.02 s. The dishes of both groups were inserted into magnetic tweezer cytometry for applying a magnetic force pulse, and the cell membrane displacement was detected by an image processing system. The creep response of the membrane was determined for viscoelastic model curve fitting. The frequency responses of the model for both groups were calculated. The results showed that radiation could decrease cell extensibility from 0.084 ± 0.001 to 0.019 ± 0.001 µm and change the storage and loss modulus as the indicator of the viscoelastic property of the material. This research explains that radiation could affect cellular mechanical properties.