Close-packed monolayers of charged Janus-type nanoparticles at the air-water interface

► Novel approach to obtain monolayer of charged nanoparticles at air-water interface. ► Charged nanoparticles possess Janus-type structure. ► Positively and negatively charged nanoparticles are employed. ► Monolayer can be compressed to form stable close-packed array of nanoparticles. ► Langmuir-Blodgett technique used to transfer monolayer on solid substrate.