Natural unmodified rhamnolipids are thermally self-assembled into soft microtubules, which can produce gold nanoparticles onto themselves due to the presence of rhamnose sugar moieties at their surface. The loading of gold nanoparticles on composite microtubules can be controlled by varying the concentration of gold salt to rhamnolipid and the reaction temperature. The composite rhamnolipid-gold nanopartide microtubules are then heat treated to produce porous gold microwire-like structures with fairly controlled nanostructured features, which may have interesting applications in catalysis, biosensing and electronics. (C) 2010 Elsevier Inc. All rights reserved.