A process for making nanoparticles of biocompatible materials is described, wherein an aqueous reaction mixture comprising a metal ion, a nucleobase, an oxidant, and water, is provided along with temperature conditions to directly form within the reaction mixture, a stable dispersion of nanoparticles. A joint displaces about a horizontal axis counter to the force of the spring elements, when the swivel wheel comes into contact with an obstacle. The fold formation mechanism may include a conveying path regulating part that defines a part of a conveying path of the packaging material with the conveying path regulating part temporarily bending the packaging material for a plurality of times.