Three-dimensional control of Tetrahymena pyriformis using artificial magnetotaxis
Dal Hyung Kim, Paul Seung Soo Kim, Anak Agung Julius, and Min Jun Kim
We demonstrate three-dimensional control with the eukaryotic cell Tetrahymena pyriformis (T. pyriformis) using two sets of Helmholtz coils for xy-plane motion and a single electromagnet for z-direction motion. T. pyriformis is modified to have artificial magnetotaxis with internalized magnetite. To ... [Appl. Phys. Lett. 100, 053702 (2012)] published Thu Feb 2, 2012.
A two-sphere model for bacteria swimming near solid surfaces
Jocelyn Dunstan, Gaston Mino, Eric Clement, and Rodrigo Soto
We present a simple model for bacteria like Escherichia coli swimming near solid surfaces. It consists of two spheres of different radii connected by a dragless rod. The effect of the flagella is taken into account by imposing a force on the tail sphere and opposite torques exerted by the rod over t ... [Phys. Fluids 24, 011901 (2012)] published Fri Jan 27, 2012.
Optimum quantum dot size for highly efficient fluorescence bioimaging
Laura Martinez Maestro, Carlos Jacinto, Ueslen Rocha, M. Carmen Iglesias-de la Cruz, Francisco Sanz-Rodriguez et al.
Semiconductor quantum dots of few nanometers have demonstrated a great potential for bioimaging. The size determines the emitted color, but it is also expected to play an important role in the image brightness. In this work, the size dependence of the fluorescence quantum yield of the highly thermal ... [J. Appl. Phys. 111, 023513 (2012)] published Wed Jan 25, 2012.
Chemotaxis Driven Instability of a Confined Bacterial Suspension
T. V. Kasyap and Donald L. Koch
A suspension of bacteria in a thin channel or film subject to a gradient in the concentration of a chemoattractant, will develop, in the absence of an imposed fluid flow, a steady bacteria concentration field that depends exponentially on cross-stream position. Above a critical bacteria concentratio ... [Phys. Rev. Lett. 108, 038101 ] published .
Magnetic nanomanipulations inside living cells compared with passive tracking of nanoprobes to get consensus for intracellular mechanics
Damien Robert, Kelly Aubertin, Jean-Claude Bacri, and Claire Wilhelm
During the last decade, the development of nanomaterials to penetrate inside living cells has been the focus of a large number of studies, with applications for the biomedical field. However, the further dynamics of these nanomaterials inside the cells is dictated by the intracellular environment an ... [Phys. Rev. E 85, 011905 ] published .
Cellular ability to sense spatial gradients in the presence of multiple competitive ligands
Shu-Hao Liou and Chia-Chu Chen
Many eukaryotic and prokaryotic cells can exhibit remarkable sensing ability under small gradients of chemical compounds. In this study, we approach this phenomenon by considering the contribution of multiple ligands to the chemical kinetics within the Michaelis-Menten model. This work was inspired ... [Phys. Rev. E 85, 011904 ] published .
Electrotaxis of lung cancer cells in ordered three-dimensional scaffolds
Yung-Shin Sun, Shih-Wei Peng, Keng-Hui Lin, and Ji-Yen Cheng
In this paper, we report a new method to incorporate 3D scaffold with electrotaxis measurement in the microfluidic device. The electrotactic response of lung cancer cells in the 3D foam scaffolds which resemble the in vivo pulmonary alveoli may give more insight on cellular behaviors in vivo. The 3D ... [Biomicrofluidics 6, 014102 (2012)] published Wed Jan 4, 2012.
A thermodynamical model for stress-fiber organization in contractile cells
Louis Foucard and Franck J. Vernerey
Cell mechanical adaptivity to external stimuli is vital to many of its biological functions. A critical question is therefore to understand the formation and organization of the stress fibers from which emerge the cell's mechanical properties. By accounting for the mechanical aspects and the viscoel ... [Appl. Phys. Lett. 100, 013702 (2012)] published Wed Jan 4, 2012.
Estimating the bending modulus of a FtsZ bacterial-division protein filament
Eric N. Cytrynbaum, Yongnan Devin Li, Jun F. Allard, and Hadi Mehrabian
FtsZ, a cytoskeletal protein homologous to tubulin, is the principle constituent of the division ring in bacterial cells. It is known to have force-generating capacity in vitro and has been conjectured to be the source of the constriction force in vivo. Several models have been proposed to explain t ... [Phys. Rev. E 85, 011902 ] published .
Direct observation of dynamic force propagation between focal adhesions of cells on microposts by atomic force microscopy
Akinori Okada, Yusuke Mizutani, Agus Subagyo, Hirotaka Hosoi, Motonori Nakamura et al.
We investigated dynamic force propagation between focal adhesions of fibroblast cells cultured on polydimethylsiloxane micropost substrates, by atomic force microscopy. Live cells were mechanically modulated by the atomic force microscopy probe bound to cell apical surfaces at 0.010.5 Hz, while micr ... [Appl. Phys. Lett. 99, 263703 (2011)] published Thu Dec 29, 2011.
Genesis of two-dimensional patterns in cross-gradient fields
L. M. Pismen and D. S. A. Simakov
Tissue morphogenesis is controlled by the two-dimensional patterning of gene expression in epithelial layers, that determines cell fates. The mechanisms of pattern formation involve intracellular regulatory networks controlled by paracrine and autocrine signaling. We develop a general logical scheme ... [Phys. Rev. E 84, 061917 ] published .
Effects of cell cycle on the uptake of water soluble quantum dots by cells
Shen Zheng, Ji-Yao Chen, Jun-Yong Wang, Lu-Wei Zhou, and Qian Peng
Quantum dots (QDs) with excellent optical properties have become powerful candidates for cell imaging. Although numerous reports have studied the uptake of QDs by cells, little information exists on the effects of cell cycle on the cellular QD uptake. In this report, the effects of cell cycle on the ... [J. Appl. Phys. 110, 124701 (2011)] published Mon Dec 19, 2011.
Cell Motility Resulting from Spontaneous Polymerization Waves
K. Doubrovinski and K. Kruse
The crawling of cells on a substrate is in many cases driven by the actin cytoskeleton. How actin filaments and associated proteins are organized to generate directed motion is still poorly understood. Recent experimental observations suggest that spontaneous cytoskeletal waves might orchestrate the ... [Phys. Rev. Lett. 107, 258103 ] published .
Imaging the cellular response to transient shear stress using stroboscopic digital holography
Maciej Antkowiak, Yoshihiko Arita, Kishan Dholakia, and Frank Gunn-Moore
We use stroboscopic quantitative phase microscopy to study cell deformation and the response to cavitation bubbles and transient shear stress resulting from laser-induced breakdown of an optically trapped nanoparticle. A bi-directional transient displacement of cytoplasm is observed during expansion ... [J. Biomed. Opt. 16, 120508 (2011)] published Fri Dec 16, 2011.
Microwell perfusion array for high-throughput, long-term imaging of clonal growth
Huaying Chen, Jingjing Li, Han Zhang, Musen Li, Gary Rosengarten et al.
Continuous cell tracking by time-lapse microscopy has led to detailed study of cell differentiation pathways using single cell fate maps. There are a multitude of cell fate outcomes, so hundreds of clonal division histories are required to measure these stochastic branching processes. This study exa ... [Biomicrofluidics 5, 044117 (2011)] published Thu Dec 15, 2011.
Computational and experimental study of chemotaxis of an ensemble of bacteria attached to a microbead
Mahama A. Traore, Ali Sahari, and Bahareh Behkam
Micro-objects propelled by whole cell actuators, such as flagellated bacteria, are being increasingly studied and considered for a wide variety of applications. In this work we present theoretical and experimental investigations of chemotactic motility of a 10 [mu]m diameter microbead propelled by a ... [Phys. Rev. E 84, 061908 ] published .
Macroion solutions in the cell model studied by field theory and Monte Carlo simulations
Leo Lue and Per Linse
Aqueous solutions of charged spherical macroions with variable dielectric permittivity and their associated counterions are examined within the cell model using a field theory and Monte Carlo simulations. The field theory is based on separation of fields into short- and long-wavelength terms, which ... [J. Chem. Phys. 135, 224508 (2011)] published Mon Dec 12, 2011.
Energetics of synchronized states in three-dimensional beating flagella
Clement Mettot and Eric Lauga
During collective locomotion, beating flagella of spermatozoa interact hydrodynamically and are observed experimentally to synchronize. G. I. Taylor used a small-amplitude two-dimensional sheet model to show that the rate at which swimmers do work against the fluid is minimal for in-phase beating. W ... [Phys. Rev. E 84, 061905 ] published .
Effect of viscoelasticity on the collective behavior of swimming microorganisms
Yaser Bozorgi and Patrick T. Underhill
Hydrodynamic interactions of swimming microorganisms can lead to coordinated behaviors of large groups. Using a mean-field theory and the Oldroyd-B constitutive equation, we show how linear viscoelasticity of the suspending fluid alters the hydrodynamic interactions and therefore the ability of the ... [Phys. Rev. E 84, 061901 ] published .
Mathematical Modeling of Chemoatractant Effects on Cell Movement
A. Prieto-Langarica, H. V. Kojouharov, and B. M. Chen-Charpentier
Cell migration plays a vital role throughout the life span of organisms. In many cases this movement is governed by the presence of certain chemicals which attract or repel the cells. In this paper, we present a cellular automata model that describes the movement of cells which are attracted to a ch ... [AIP Conf. Proc. 1404, 184 (2011)] published Tue Nov 29, 2011.
Multifrequency impedance measurement technique for wireless characterization of microbiological cell cultures
J. Wissenwasser, M. J. Vellekoop, W. Kapferer, G. Lepperdinger, and R. Heer
An impedance measurement system with probe signal frequencies up to 50 kHz with AC-probe voltages below 30 mV rms was integrated for wireless and battery-free monitoring of microbiological cell cultures. The here presented modular design and the use of state-of-the-art components greatly eases adopt ... [Rev. Sci. Instrum. 82, 115110 (2011)] published Tue Nov 29, 2011.