Fabrication of Large‐Area Two‐Dimensional Colloidal Crystals

Nanoparticle coating: A suspension of colloidal particles in a water/propanol solution was layered onto a water surface, where the particles self-assembled into ordered two-dimensional hexagonal crystal arrays (>280 cm 2) within two minutes. These arrays were transferred from the water surface to other substrates (see picture) and embedded in a chitosan hydrogel for visual detection of the pH value. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.