@article {105899, title = {Assembling anisotropic colloids using curvature-mediated lipid sorting.}, journal = {Soft Matter}, year = {2022}, month = {2022 Jan 24}, abstract = {

The use of colloid supported lipid bilayers (CSLBs) for assembling colloidal structures has been of recent interest. Here, we use multi-component lipid bilayer membranes formed around anisotropic colloids and show that the curvature anisotropy of the colloids drives a sorting of the lipids in the membrane along the colloids. We then exploit this curvature-sensitive lipid sorting to create "shape-anisotropic patchy colloids" - specifically, we use colloids with six rods sticking out of a central cubic core, "hexapods", for this purpose and demonstrate that membrane patches self-assemble at the tip of each of the six colloidal rods. The membrane patches are rendered sticky using biotinylated lipids in complement with a biotin-binding streptavidin protein. Finally, using these "shape-anisotropic patchy colloids", we demonstrate the directed assembly of colloidal links, paving the way for the creation of heterogeneous and flexible colloidal structures.

}, issn = {1744-6848}, doi = {10.1039/d1sm01517f}, author = {Kumar, Manoj and Singh, Anupam and Del Secco, Benedetta and Baranov, Maksim V and van den Bogaart, Geert and Sacanna, Stefano and Thutupalli, Shashi} } @article {120165, title = {Irregular particle morphology and membrane rupture facilitate ion gradients in the lumen of phagosomes.}, journal = {Biophys Rep (N Y)}, volume = {2}, year = {2022}, month = {2022 Sep 14}, pages = {100069}, abstract = {

Localized fluxes, production, and/or degradation coupled to limited diffusion are well known to result in stable spatial concentration gradients of biomolecules in the cell. In this study, we demonstrate that this also holds true for small ions, since we found that the close membrane apposition between the membrane of a phagosome and the surface of the cargo particle it encloses, together with localized membrane rupture, suffice for stable gradients of protons and iron cations within the lumen of the phagosome. Our data show that, in phagosomes containing hexapod-shaped silica colloid particles, the phagosomal membrane is ruptured at the positions of the tips of the rods, but not at other positions. This results in the confined leakage at these positions of protons and iron from the lumen of the phagosome into the cytosol. In contrast, acidification and iron accumulation still occur at the positions of the phagosomes nearer to the cores of the particles. Our study strengthens the concept that coupling metabolic and signaling reaction cascades can be spatially confined by localized limited diffusion.

}, issn = {2667-0747}, doi = {10.1016/j.bpr.2022.100069}, author = {Baranov, Maksim V and Ioannidis, Melina and Balahsioui, Sami and Boersma, Auke and de Boer, Rinse and Kumar, Manoj and Niwa, Masato and Hirayama, Tasuku and Zhou, Qintian and Hopkins, Terrence M and Grijpstra, Pieter and Thutupalli, Shashi and Sacanna, Stefano and van den Bogaart, Geert} } @article {90597, title = {Modulation of Immune Responses by Particle Size and Shape.}, journal = {Front Immunol}, volume = {607945}, year = {2021}, month = {2020}, abstract = {

The immune system has to cope with a wide range of irregularly shaped pathogens that can actively move (e.g., by flagella) and also dynamically remodel their shape (e.g., transition from yeast-shaped to hyphal fungi). The goal of this review is to draw general conclusions of how the size and geometry of a pathogen affect its uptake and processing by phagocytes of the immune system. We compared both theoretical and experimental studies with different cells, model particles, and pathogenic microbes (particularly fungi) showing that particle size, shape, rigidity, and surface roughness are important parameters for cellular uptake and subsequent immune responses, particularly inflammasome activation and T cell activation. Understanding how the physical properties of particles affect immune responses can aid the design of better vaccines.

}, issn = {1664-3224}, doi = {10.3389/fimmu.2020.607945}, author = {Baranov, Maksim V and Kumar, Manoj and Sacanna, Stefano and Thutupalli, Shashi and van den Bogaart, Geert} }