Magnetic cilia carpets with programmable metachronal waves

Metachronal waves commonly exist in natural cilia carpets. These emergent phenomena, which originate from phase differences between neighbouring self-beating cilia, are essential for biological transport processes including locomotion, liquid pumping, feeding, and cell delivery. However, studies of such complex active systems are limited, particularly from the experimental side. Here we report magnetically actuated, soft, artificial cilia carpets. By stretching and folding onto curved templates, programmable magnetization patterns can be encoded into artificial cilia carpets, which exhibit metachronal waves in dynamic magnetic fields. We have tested both the transport capabilities in a fluid environment and the locomotion capabilities on a solid surface. This robotic system provides a highly customizable experimental platform that not only assists in understanding fundamental rules of natural cilia carpets, but also paves a path to cilia-inspired soft robots for future biomedical applications.

Integrated approaches to unravel the impact of protein lipoxidation on macromolecular interactions

Protein modification by lipid derived reactive species, or lipoxidation, is increased during oxidative stress, a common feature observed in many pathological conditions. Biochemical and functional consequences of lipoxidation include changes in the conformation and assembly of the target proteins, altered recognition of ligands and/or cofactors, changes in the interactions with DNA or in protein-protein interactions, modifications in membrane partitioning and binding and/or subcellular localization. These changes may impact, directly or indirectly, signaling pathways involved in the activation of cell defense mechanisms, but when these are overwhelmed they may lead to pathological outcomes. Mass spectrometry provides state of the art approaches for the identification and characterization of lipoxidized proteins/residues and the modifying species. Nevertheless, understanding the complexity of the functional effects of protein lipoxidation requires the use of additional methodologies. Herein, biochemical and biophysical methods used to detect and measure functional effects of protein lipoxidation at different levels of complexity, from in vitro and reconstituted cell-like systems to cells, are reviewed, focusing especially on macromolecular interactions. Knowledge generated through innovative and complementary technologies will contribute to comprehend the role of lipoxidation in pathophysiology and, ultimately, its potential as target for therapeutic intervention.

Compartments for Synthetic Cells: Osmotically Assisted Separation of Oil from Double Emulsions in a Microfluidic Chip

Liposomes are used in synthetic biology as cell-like compartments and their microfluidic production through double emulsions allows for efficient encapsulation of various components. However, residual oil in the membrane remains a critical bottleneck for creating pristine phospholipid bilayers. It has been discovered that osmotically driven shrinking leads to detachment of the oil drop. Separation inside a microfluidic chip has been realized to automate the procedure, which allows for controlled continuous production of monodisperse liposomes.

Biologically Inspired Design of Nanoparticle Artificial Antigen-Presenting Cells for Immunomodulation

Particles engineered to engage and interact with cell surface ligands and to modulate cells can be harnessed to explore basic biological questions as well as to devise cellular therapies. Biology has inspired the design of these particles, such as artificial antigen-presenting cells (aAPCs) for use in immunotherapy. While much has been learned about mimicking antigen presenting cell biology, as we decrease the size of aAPCs to the nanometer scale, we need to extend biomimetic design to include considerations of T cell biology-including T-cell receptor (TCR) organization. Here we describe the first quantitative analysis of particle size effect on aAPCs with both Signals 1 and 2 based on T cell biology. We show that aAPCs, larger than 300 nm, activate T cells more efficiently than smaller aAPCs, 50 nm. The 50 nm aAPCs require saturating doses or require artificial magnetic clustering to activate T cells. Increasing ligand density alone on the 50 nm aAPCs did not increase their ability to stimulate CD8+ T cells, confirming the size-dependent phenomenon. These data support the need for multireceptor ligation and activation of T-cell receptor (TCR) nanoclusters of similar sizes to 300 nm aAPCs. Quantitative analysis and modeling of a nanoparticle system provides insight into engineering constraints of aAPCs for T cell immunotherapy applications and offers a case study for other cell-modulating particles.

Self-Assembly of Bilayer Vesicles Made of Saturated Long Chain Fatty Acids

Saturated long chain fatty acids (sLCFA, e.g., C14:0, C16:0, and C18:0) are potentially the greenest and cheapest surfactants naturally available. However, because aqueous sodium soaps of sLCFA are known to crystallize, the self-assembly of stable bilayer vesicles has not been reported yet. Here, by using such soaps in combination with guanidine hydrochloride (GuHCl), which has been shown recently to prevent crystallization, we were capable of producing stable bilayer vesicles made of sLCFA. The phase diagrams were established for a variety of systems showing that vesicles can form in a broad range of composition and pH. Both solid state NMR and small-angle neutron scattering allowed demonstrating that in such vesicles sLCFA are arranged in a bilayer structure which exhibits similar dynamic and structural properties as those of phospholipid membranes. We expect these vesicles to be of interest as model systems of protocells and minimal cells but also for various applications since fatty acids are potentially substitutes to phospholipids, synthetic surfactants, and polymers.

Specific transformation of assembly with actin filaments and molecular motors in a cell-sized self-emerged liposome

Eukaryotes, by the same combination of cytoskeleton and molecular motor, for example actin filament and myosin, can generate a variety of movements. For this diversity, the organization of biological machineries caused by the confinement and/or crowding effects of internal living cells, may play very important roles.

Emergence of photoautotrophic minimal protocell-like supramolecular assemblies, "Jeewanu" synthesied photo chemically in an irradiated sterilised aqueous mixture of some inorganic and organic substances

Sunlight exposed sterilised aqueous mixture of ammonium molybdate, diammonium hydrogen phosphate, biological minerals and formaldehyde showed photochemical formation of self-sustaining biomimetic protocell-like supramolecular assemblies "Jeewanu" (Bahadur and Ranganayaki J Brit Interplanet Soc 23:813-829 1970). The structural and functional characteristics of Jeewanu suggests that in possible prebiotic atmosphere photosy nergistic collaboration of non-linear processes at mesoscopic level established autocatalytic pathways on mineral surfaces by selforganisation and self recognition and led to emergence of similar earliest energy transducing supramolecular assemblies which might have given rise to common universal ancestor on the earth or elsewhere.