Determination of Cell Stiffness Using Polymer Microbeads as Reference

Knowing the mechanical properties of cells is very important in cell detection, analysis of cell activities, diagnosis and drug treatment. The determination of cell stiffness, which used effectively in cell analysis, is carried out with different measurement techniques. In this study, the stiffness of cells is determined by comparison to the displacement of polystyrene microparticles induced by vibration generated by piezoelectric transducers. The difference of stiffness of the cells and polystyrene microparticles is measured using a digital holographic imaging technique

Classification of Cells Based on Their Drifting Velocity under Acoustic Radiation Pressure

© 2020 IEEE.This study reports a novel cell classification method based on the observation of trajectories that cells inside a fluidic chamber follow under an externally applied acoustic field. Proposed method is significant both as a cell classification method and as a method for characterising the motion of various cell lines under different surface acoustic wave patterns. The difference is mainly due to the characteristic differences of cells such as mass, surface adhesiveness and cellular volume. We discuss the mechanisms that affect the interaction between cells and surface waves. Classification performance is tested using using support vector machine (SVM), max-likelihood and multilayer perceptron (MLP) methods and accuracy, sensitivity and specificity values are reported for each. The results indicate that the method can be used as a powerful classifier particularly for cells that are hard to distinguish visually. It is observed that for a given frequency, the motion characteristics of different cell lines differ due to the difference between dominant adhesion mechanism for that particular cell line. This observation can be utilized for the development of a frequency based cell manipulation method that is able to target specific cells using their characteristic frequencies. We discuss the potential of the proposed acoustic stimulation method as a cell manipulation technique particularly for uncoupling the motion of different cell lines

Manipulation of Cell Cultures by Means of Holographic Visual Feedback

© 2020 IEEE.In this study we present a novel untethered micro tool that is able to accomplish minimally invasive micro manipulation tasks in 2D and 3D cell cultures. We demonstrate the proposed system for targeted drug delivery, cell translation and mechanical cell stimulation applications. Due to the ability of the proposed system to control the motion of the micro tool in 6 DOF and obtain depth information through holographic visual feedback, we show that the microtool can be manipulated in a way such that the sample cell culture will go negligible mechanical stress. We show that the proposed system can be used for a variety of micro manipulation tasks without effecting the sample in question

Interferometric Investigation of Cell Stiffness and Morphology on Oxidative Stress- Induced Human Umbilical Vein Endothelial Cells (HUVEC)

Cell stiffness that can be measured accordingly elasticity modulus is an important biomechanical feature that plays a one-to-one role on the basic features of the cell, such as migration and proliferation, and this feature is significantly affected by the characteristic of the cytoskeleton. Reactive Oxygen Species (ROS) are side-products formed as a result of the cell's general metabolic activities. Cells have a very effective antioxidant defense to deactivate the toxic effect of ROS however, oxidative stress at abnormal levels significantly damages cellular balance. Many conditions such as inflammation, neurodegenerative and cardiovascular diseases and aging are associated with oxidative stress. Besides, oxidative stress is one of the parameters that affect the biomechanical behavior of the cell, but the mechanism of this effect still remains a mystery. In this study, oxidative stress was mimicked on Human Umbilical Vein Endothelial (HUVEC) cells by using H2O2 and the effect of this situation on cell stiffness and morphological structure was investigated interferometrically for the first time. The changes that occurred in the cell stiffness were determined by calculating the elasticity modules of the cells. Cells were exposed to H2O2 for 24 hours at 0.5 mM and 1 mM concentrations, and as a result, cell stiffness was shown to decrease due to increased H2O2 concentration

Optimization of Different Surface Modifications for Binding of Tumor Cells in a Microfluidic Systems

Objectives:Microfluidic technology is a fast-growing area and provide high-efficient MEMS (Micro-Electro-Mechanical-Systems) sensor integration platform that helps to advance healthcare systems. Due to proper the chemical and mechanical properties of polymers, PDMS (Polydimethylsiloxane) (6) and PMMA (Poly-methyl-methacrylate), they became on the best candidate for health care studies in microfluidic studies (7). Besides, they perform great optical properties for observation of living cell experiments. To increase their performance, surface interactions works with cells, modification techniques are widely used in microfluidic chips. In this paper, our primary purpose is to modify such polymers and glass with matrigel, PDA and APTES so as to increase cell-surface interaction

Holographic Cell Stiffness Mapping Using Acoustic Stimulation

Accurate assessment of stiffness distribution is essential due to thecritical role of single cell mechanobiology in the regulation of many vitalcellular processes such as proliferation, adhesion, migration, and motility.Cell stiffness is one of the fundamental mechanical properties of the cell andis greatly affected by the intracellular tensional forces, cytoskeletalprestress, and cytoskeleton structure. Herein, we propose a novel holographicsingle-cell stiffness measurement technique that can obtain the stiffnessdistribution over a cell membrane at high resolution and in real-time. Theproposed imaging method coupled with acoustic signals allows us to assess thecell stiffness distribution with a low error margin and label-free manner. Wedemonstrate the proposed technique on HCT116 (Human Colorectal Carcinoma) cellsand CTC-mimicked HCT116 cells by induction with transforming growth factor-beta(TGF-\b{eta}). Validation studies of the proposed approach were carried out oncertified polystyrene microbeads with known stiffness levels. Its performancewas evaluated in comparison with the AFM results obtained for the relevantcells. When the experimental results were examined, the proposed methodologyshows utmost performance over average cell stiffness values for HCT116, andCTC-mimicked HCT116 cells were found as 1.08 kPa, and 0.88 kPa, respectively.The results confirm that CTC-mimicked HCT116 cells lose their adhesion abilityto enter the vascular circulation and metastasize. They also exhibit a softerstiffness profile compared to adherent forms of the cancer cells. Hence, theproposed technique is a significant, reliable, and faster alternative forin-vitro cell stiffness characterization tools. It can be utilized for variousapplications where single-cell analysis is required, such as disease modeling,drug testing, diagnostics, and many more

Acousto-holographic reconstruction of whole-cell stiffness maps

Accurate assessment of cell stiffness distribution is essential due to the critical role of cell mechanobiology in regulation of vital cellular processes like proliferation, adhesion, migration, and motility. Stiffness provides critical information in understanding onset and progress of various diseases, including metastasis and differentiation of cancer. Atomic force microscopy and optical trapping set the gold standard in stiffness measurements. However, their widespread use has been hampered with long processing times, unreliable contact point determination, physical damage to cells, and unsuitability for multiple cell analysis. Here, we demonstrate a simple, fast, label-free, and high-resolution technique using acoustic stimulation and holographic imaging to reconstruct stiffness maps of single cells. We used this acousto-holographic method to determine stiffness maps of HCT116 and CTC-mimicking HCT116 cells and differentiate between them. Our system would enable widespread use of whole-cell stiffness measurements in clinical and research settings for cancer studies, disease modeling, drug testing, and diagnostics.ISSN:2041-172