Water-dispersible polyaniline colloids with photosensitivity were prepared by enzymatic polymerization using the photo- and temperature-responsive azopolymer: N,N-dimethylacrilamide (DMA)-co-N-4-phenylazo-phenylacrylamide (AZAAm) copolymer, poly(DMA-co-AZAAm), as steric stabilizer. The resulting polyaniline nanoparticles showed an interesting photoisomerization behavior in water solution, as indicated by H-1 NMR and UV-vis spectra obtained after irradiation with UV light at 365 nm. Its comparative analysis with poly(DMA-co-AZAAm) was realized. The effect of the steric stabilizer on the morphology of the polyaniline was studied by AFM and SEM analysis of the polyaniline synthesized with and without azopolymer. Additional characterization such as molecular weight and infrared spectra were performed. (C) 2010 Elsevier B.V. All rights reserved.