Microfluidics-enabled core/shell nanostructure assembly: Understanding encapsulation processes via particle characterization and molecular dynamics

In the realm of hybrid nanomaterials, the construction of core/shell nanoparticles offer an effective strategy for encompassing a particle by a polymeric or other suitable material, leading to a nanocomposite with distinct features within its structure. The polymer shell can be formed via nanoprecipitation, optimized by manipulating fluid flow, fluid mixing, modulating device features in microfluidics. In addition to the process optimization, success of polymer assembly in encapsulation strongly lies upon the favorable molecular interactions originating from the diverse chemical environment shared between core and shell materials facilitating formation of core/shell nanostructure. Therefore, understanding particle surface related properties and interaction profile of core/shell, is pertinent to fully harness control over core/shell structure formation. In our study, employing microfluidics-assisted screening of diverse MSN cores with contrasting charged dextran derived polymers, we conducted detailed characterization using dynamic light scattering (DLS), transmission electron microscope (TEM) imaging, and molecular simulations (MD) for analyzing interaction energies and molecular interactions. Our findings reveal that self-assembly of a polymer around the MSN cores majorly proceeds among counter charged entities (core and shell). From molecular perspective, in addition to the electrostatic interactions, hydrogen bonded interactions also contribute to stabilizing polymer assembly. Contrarily, out data reveals that in case pi-cation and van der Waals interactions are dominant, encapsulation of MSN cores accomplishes regardless of particle surface charge. Therefore, by integrating morphological characterization and molecular insights from computational studies, we summarize the synthesis mechanism of core/shell nanostructures.