Single-Step Microfluidics-Based Method for Fabrication of Nanoparticle-Coated Functional Microfibers

Fibers coated with nanoparticles have diverse applications as catalysts, biosensors, tissue scaffolds, and adsorbents for contaminants in water purification. However, current fabrication techniques employ multistep processes that often result in uneven nanoparticle coatings, consequently leading to reduced activity. Here we present a single-step microfluidics-based approach for the generation of microfibers with uniformly coated nanoparticles. Inside a microfluidic device, magnesium oxide (MgO) nanoparticles are deposited onto a poly(vinylidene fluoride) (PVDF) polymer solution jet that is solidifying into fibers through solvent evaporation. The formed fibers display a uniform coating of nanoparticles on their surfaces, which is a crucial requirement in all applications. Using these fibers for water purification, we demonstrate that a single adsorbent of MgO can effectively remove multiple heavy metal contaminants, including As(III), As(V), Pb(II), Cd(II), and both As(III) and As(V) together. Remarkably, MgO nanoparticles, when coated onto fibers, have shown higher contaminant removal efficiency than when used alone, arguably due to the greater nanoparticle surface area available in the coated form. The developed microfluidic technique could possibly be used to fabricate various other nanomaterial (nanorods, quantum dots, and proteins) coated fibers, leading to a diverse array of applications.