In the present invention, biodegradable nanocomposites are introduced which include nanoclay particles, titanium dioxide nanoparticles, polyethylene, polypropylene, starch as a biopolymer, maleic anhydride and glycerol. The obtained nanocomposites have very high physical, mechanical and antimicrobial properties. Proper dispersion and distribution of nanoparticles in composite substrate would help in improving the quality of the product to a great extent. The presence of polypropylene next to polyethylene would eliminate the weak points of polyethylene/biopolymer composite as polypropylene helps to modify the physical and engineering properties of nanocomposites in the presence of nanoclay. Titanium dioxide nanoparticles have antimicrobial properties and would result in products which are useful for food and pharmaceutical industries. Another important aspect of this invention is the production of samples in one step by reaction extrusion method.