Provided is a coated article comprising a substrate and a dried coating which comprises a first set of spherical silica nanoparticles having an average diameter of less than 20 nm and a second set of spherical silica nanoparticles having an average diameter of 20 nm to 120 nm. The alkoxy silane compound comprises an epoxy functional group or a carboxylic acid functional group. Also provided is a coating composition comprising an acidic aqueous dispersion which comprises the described first and second set of spherical silica nanoparticles and silane compound.