Polydiacetylene (PDA), which can change the chromic and fluorescence properties by inducing environmental perturbations, is immobilized on planar solid supports for many biological applications. In this work, we immobilize PDA onto optically encoded spherical beads (PDA-SERS beads). The prepared PDA immobilized beads (36 mu m) exhibit a blue color without fluorescence. By inducing stress, their color and fluorescence properties are changed to red with fluorescence. The SERS spectra of the PDA-SERS beads can be recognized over the PDA background. Moreover, our PDA immobilization methods are successfully applied to silica-surface SERS-encoded beads (5 mu m) and proven to also be useful in fluorescence encoding systems. (C) 2010 Elsevier Inc. All rights reserved.