Preparation of free-suspended polyelectrolyte multilayer films using an alginate scaffold and their ion permeability

► Free-suspended layer-by-layer thin films can be prepared using alginate scaffold. ► Free-suspended layer-by-layer thin films are used for selective ion transport. ► Free-suspended layer-by-layer thin films exhibit ion selectivity depending on the surface charge. ► Transport of multivalent ions across the LbL films is significantly suppressed.