Squishy Non-Spherical Hydrogel Microparticles

available in PMC 2011 July 15Recent advances in the synthesis of polymeric colloids have opened the doors to new advanced materials. There is strong interest in using these new techniques to produce particles that mimic and/or interact with biological systems. An important characteristic of biological systems that has not yet been exploited in synthetic polymeric colloids is their wide range of deformability. A canonical example of this is the human red blood cell (RBC) which exhibits extreme reversible deformability under flow. Here we report the synthesis of soft polymeric colloids with sizes and shapes that mimic those of the RBC. Additionally, we demonstrate that the mechanical flexibility of the colloids can be reproducibly varied over a large range resulting in RBC-like deformability under physiological flow conditions. These materials have the potential to impact the interaction between biological and synthetic systems.Massachusetts Institute of Technology (MIT-MGH Fellowship in Translational Research)Massachusetts General Hospital (MIT-MGH Fellowship in Translational Research)National Institute of Biomedical Imaging and Bioengineering (U.S.) (BioMEMS Resource Center, P41 EB002503)John Simon Guggenheim Memorial FoundationInstitut Curie (Rothschild-Yvette-Mayent-Institute Curie Fellowship

Peptide-based microcapsules obtained by self-assembly and microfluidics as controlled environments for cell culture

Funding for this study was provided by the Portuguese Foundation for Science and Technology (FCT, grant PTDC/EBB-BIO/ 114523/2009). D. S. Ferreira gratefully acknowledges FCT for the PhD scholarship (SFRH/BD/44977/2008)

MR fluid structure in quasi-2D

We study the effects of quasi-two-dimensional (quasi-2D) confinement on the self-assembly of super paramagnetic colloids found in magnetorheological (MR) fluids using the Brownian dynamics simulation technique. A uniform external magnetic field is directed normal to a thin-slit in which dilute MR fluid is confined. The thickness of the confining slit ranges from a single colloid diameter to several colloid diameters. The steady-state structure that forms under such extreme confinement is shown to depend heavily upon the thickness of the slit. As the slit-thickness is increased from one colloid diameter (2D confinement) the structure of the dilute MR fluid changes non-monotonically. We introduce a ground-state model to predict the structure as a function of the slit-thickness and the volume fraction of the fluid. The model is able to quantitatively predict the structures observed in our simulations