The present invention provide water soluble polyfluorenes functionalized with glucuronic acid useful in sensing bilirubin in aqueous medium and process for preparation thereof. The invention further deals with detecting bilirubin in human serum samples in the range from normal (< 25 umol/L - 1.2 mg/dL) human bilirubin level to jaundiced bilirubin level (> 50 umol/L - 25mg/dl)" This is a fluorescence tum-off mode of detection where blue fluorescence of polymer quenches and becomes colorless. The water soluble polyfluorenes functionalized with glucuronic acid can detect free bilirubin in the range from lx10-" M to lx 1 0 - "7 M moles in aqueous and buffer media as a change in the fluorescence signal.
