Long-range attractive forces extending from alumina nanofiber surface

Aluminum oxide-hydroxide nanofibers, 2 nm in diameter and approximately 250 nm long, are electroadhesively grafted onto glass microfibers, therefore forming a macroscopic assembly of alumina nanofibers on the second solid in highly organized matter. The assembly can be viewed as a straight cylinder with rough surface and charge density of approximately 0.08 C/m 2 . This creates a significant electric field with negligible screening (ka ≪ 1) in the region close to the surface of the assemblies. This field attracts nano- and micron-size particles from as far as 0.3 mm in less than a few seconds, many orders of magnitude greater than the conventional Derjaguin-Landau-Verwey-Overbeek theory that predicts only nanometer-scale effects arising from the presence of the surface. The strong electric field on the surface is then able to retain particles such as micron-size powdered activated carbon as well as much smaller particles such as fumed silica nanoparticles of 10-15 nm in diameter, viruses, atomically thick sheets of graphene oxide, latex spheres, RNA, DNA, proteins, and dyes.