Madivala G. Basavaraj

Janus particles provide a powerful platform for studying asymmetric surface functionality and active colloidal matter, yet their broader utilization is hindered by the lack of fabrication strategies that offer quantitative and independent control over patch geometry. Here, we report an interfacial confinement-assisted electroless deposition process that exploits irreversible particle adsorption at the liquid–liquid interface for directed metal deposition. This process enables systematic control over metal patch thickness (5–50 nm) and surface coverage while remaining robust to the deposition of various metals (Au, Ag, Pt, Ni, Cu) and scalable across centimeter-scale interfacial areas (≈ 16 cm2). The generality of the approach is demonstrated by the synthesis of Janus particles with varied shapes (sphere, ellipsoid, peanut, sphero-cylinder, cube) and surface chemistries (hematite, silica, polystyrene, p-NIPAM) at liquid–liquid interfaces formed with different oils. To characterize the activity of particles, we perform experiments in hydrogen peroxide solutions of varying concentrations and demonstrate the influence of the catalytic patch thickness on the self-propulsion of Janus particles. Because the proposed process relies on general principles of colloids and interfacial chemistry, it is readily extendable to diverse systems and provides a versatile chemical route to architected Janus colloids.

Microgranules are a class of synthetic functional materials designed for the delivery of active compounds in diverse sectors, including pharmaceuticals, agriculture, food, and cosmetics. In this work, we present a scalable emulsion-based method for fabricating microgranules with robust mechanical and structural properties. We successfully encapsulate an antidiabetic drug within these microgranules and analyze drug loading using microscopy, spectroscopy, and thermal techniques. In vitro drug release profiles are obtained and modeled to understand the underlying release mechanism. Biocompatibility assessments using the MTT assay confirm the excellent cytocompatibility of drug-loaded microgranules. Overall, the emulsion-based approach offers a versatile and scalable platform for the encapsulation and controlled release of therapeutic agents and other functional molecules.

PNIPAM microgels, a model soft colloid known to respond to external stimuli such as temperature or pH, show significantly different swelling kinetics at the fluid-fluid interface compared to bulk. When an aqueous dispersion of these microgels dries on a solid substrate, they adsorb onto the air-water interface and undergo significant flattening along the interface. This interfacial rearrangement enables the formation of ordered monolayers, offering a bottom-up route for fabricating colloidal films. Leveraging on their temperature-responsive swelling and surface activity, we investigate how poly(N-isopropylacrylamide) (PNIPAM) microgels can be used to obtain complex deposition patterns by drying sessile aqueous drops containing microgels at different concentrations on hydrophilic substrates maintained at temperatures, below and above the volume phase transition temperature (VPTT) of the microgels. The evaporation dynamics of the drop is monitored using in situ video microscopy and a contact angle goniometer, while the resulting microstructures are characterized using atomic force microscopy (AFM). Our observations reveal a rich diversity in final deposit morphologies, ranging from uniform films to classic coffee-ring and multiring patterns. These deposition outcomes depend on both the initial particle concentration and the substrate temperature. Notably, we find that the average height of the dried microgels increases with the substrate temperature. Moreover, spatial heterogeneity in the height profiles of the microgels across different regions of the deposits suggests that thermally modulated interfacial behavior of the microgels plays a critical role in directing their self-assembly during evaporation.

An inverse dicephalic peptide surfactant with two aromatic hydrophobic heads and a collagen-inspired hydrophilic tail self-assembles and delivering low CAC, unimicellar aggregates, and tunable interfacial performance.