The alkaline oxidation of L-cysteine (L-Cys) was conducted in aqueous media forming the insoluble L-cystine dimer as confirmed by X-ray diffraction. In another experiment, a gallium nitride film was added to the L-Cys solution and the L-cystine crystals presented a preferential growth. The transmission electron microscopy images showed the formation of single- and multi-wall L-cystine nanotubes. The infrared and high resolution electron microscopy data suggested that the growth of the tubes resulted from the successive staking of L-cystine dimers onto the (0 0 1) family of planes, which was a consequence of the ionic assembly between L-cystine over a layer of L-Cys molecules previously grafted to the gallium nitride particles. (C) 2013 Elsevier B.V. All rights reserved.