||Water-soluble conjugated polymers are being extensively investigated for their potential applications in the fields of optoelectronics, and chemical and biological sensors. Especially, Fluorescent conjugated polymers have remarkable efficiency of signal amplification compared with corresponding monomer. Spherical gel beads containing conjugated polymers have been applied in the microcarrier and sensor scaffold. As gel materials, polyelectrolyte complex systems have often been used. Among them, calcium alginate is the most commonly employed system for its easiness in gel formation. Once liquid alginate solutions are contacted with polycation(Ca2+), they immediately transformed into gel by binding between guluronic acid blocks in alginate and Ca2+. Herein, we synthesis cationic polymer which has self aggregation property in solid state and immobilize in alginate bead. As a result, fluorescence color change is induced by aggregation based on phase transition.