Publications
Double‑emulsion templated lipid vesicles as minimal cell mimics for assembling tissue‑like vesicular materials
Lipid vesicles formed using double-emulsion drops as templates exhibit uniform sizes and compositions. Despite these important advantages, conventional electroformation continues to be the selected approach for vesicle fabrication to understand biophysical processes in cells using simplified model systems. Here, we address critical aspects that could be hindering the extensive use of emulsion-templating strategies for vesicle fabrication and emphasize certain systematic studies that would help demonstrate further the advantages of microfluidic technologies. Besides the importance of controlling size and composition, we envision that the high throughput of this technology will allow the construction of vesicular materials with controlled architectures.
Metamaterials for Active Colloid Transport
Transport phenomena in out-of-equilibrium systems is immensely important in a myriad of applications in biology, engineering and physics. Complex environments, such as the cytoplasm or porous media, can substantially affect the transport properties of such systems. In particular, recent interest has focused on how such environments affect the motion of active systems, such as colloids and organisms propelled by directional driving forces. Nevertheless, the transport of active matter with non-directional (rotational) activity is yet to be understood, despite the ubiquity of rotating modes of motion in synthetic and natural systems. Here, we report on the discovery of spatiotemporal metamaterial systems that are able to dictate the transport of spinning colloids in exquisite ways based on solely two parameters: frequency of spin modulation in time and the symmetry of the metamaterial. We demonstrate that dynamic modulations of the amplitude of spin on a colloid in lattices with rotational symmetry give rise to non-equilibrium ballistic transport bands, reminiscent of those in Floquet-Bloch systems. By coupling these temporal modulations with additional symmetry breaking in the lattice, we show selective control from 4-way to 2-way to unidirectional motion. Our results provide critical new insights into the motion of spinning matter in complex (biological) systems. Furthermore, our work can also be used for designing systems with novel and unique transport properties for application in, for example, smart channel-less microfluidics, micro-robotics, or colloidal separations.
Calcium-triggered fusion of lipid membranes is enabled by amphiphilic nanoparticles
​Lipid membrane fusion is an essential process for a number of critical biological functions. The overall process is thermodynamically favorable but faces multiple kinetic barriers along the way. Inspired by nature’s engineered proteins such as SNAP receptor [soluble N-ethylmale-imide-sensitive factor-attachment protein receptor (SNARE)] complexes or viral fusogenic proteins that actively promote the development of membrane proximity, nucleation of a stalk, and triggered expansion of the fusion pore, here we introduce a synthetic fusogen that can modulate membrane fusion and equivalently prime lipid membranes for calcium-triggered fusion. Our fusogen consists of a gold nanoparticle functionalized with an amphiphilic monolayer of alkanethiol ligands that had previously been shown to fuse with lipid bilayers. While previous efforts to develop synthetic fusogens have only replicated the initial steps of the fusion cascade, we use molecular simulations and complementary experimental techniques to demonstrate that these nanoparticles can induce the formation of a lipid stalk and also drive its expansion into a fusion pore upon the addition of excess calcium. These results have important implications in general understanding of stimuli-triggered fusion and the development of synthetic fusogens for biomedical applications.