The flexibility and waveguiding properties of fiber-shaped aggregates self-assembled from thiacyanine dye molecules in solution were investigated. Sharply bent fibers were prepared by drop-casting a solution containing the fibers on a glass substrate and immediately soaking up the solution. It was found that the fibers could be smoothly bent down to a radius of curvature R approximate to 2 mu m. Fluorescence microscopy revealed that the fibers guide their fluorescence along such sharp bends. The bending losses were quantitatively measured using laser scanning optical microscopy. (c) 2007 Elsevier B.V. All rights reserved.